Electron beam injectors are pivotal components of large-scale scientific instruments,such as synchrotron radiation sources,free-electron lasers,and electron-positron colliders.The quality of the electron beam produced...Electron beam injectors are pivotal components of large-scale scientific instruments,such as synchrotron radiation sources,free-electron lasers,and electron-positron colliders.The quality of the electron beam produced by the injector critically influences the performance of the entire accelerator-based scientific research apparatus.The injectors of such facilities usually use photocathode and thermionic-cathode electron guns.Although the photocathode injector can produce electron beams of excellent quality,its associated laser system is massive and intricate.The thermionic-cathode electron gun,especially the gridded electron gun injector,has a simple structure capable of generating numerous electron beams.However,its emittance is typically high.In this study,methods to reduce beam emittance are explored through a comprehensive analysis of various grid structures and preliminary design results,examining the evolution of beam phase space at different grid positions.An optimization method for reducing the emittance of a gridded thermionic-cathode electron gun is proposed through theoretical derivation,electromagnetic-field simulation,and beam-dynamics simulation.A 50%reduction in emittance was achieved for a 50 keV,1.7 A electron gun,laying the foundation for the subsequent design of a high-current,low-emittance injector.展开更多
Combustion instability is a very important issue in the development of the propulsion systems used in aerospace. It is very important to associate the high frequency combustion instabilities with the acoustic characte...Combustion instability is a very important issue in the development of the propulsion systems used in aerospace. It is very important to associate the high frequency combustion instabilities with the acoustic characteristics of the combustion chamber. In this paper, the effects of various baffle injectors which were installed on the injector faceplate on the first-order tangential acoustic mode were investigated theoretically and experimentally. The effects of the gap between adjacent injectors on the first-order tangential acoustic mode in a cylindrical chamber were considered. The acoustic admittance of the injectors was derived. The results showed that the amplitude and frequency of the first-order tangential acoustic mode increase with the increase in the gap between adjacent injectors, but decrease with the increase in the number and height of the baffles.The baffle injectors have a greater influence on the amplitude and frequency of the first-order tangential acoustic mode than the baffle blades.展开更多
Fuel injectors are considered as an important component of combustion engines. Operational weakness can possibly lead to the complete machine malfunction, decreasing reliability and leading to loss of production. To o...Fuel injectors are considered as an important component of combustion engines. Operational weakness can possibly lead to the complete machine malfunction, decreasing reliability and leading to loss of production. To overcome these circumstances, various condition monitoring techniques can be applied. The application of acoustic signals is common in the field of fault diagnosis of rotating machinery. Advanced signal processing is utilized for the construction of features that are specialized in detecting fuel injector faults. A performance comparison between novelty detection algorithms in the form of one-class classifiers is presented. The one-class classifiers that were tested included One-Class Support Vector Machine (OCSVM) and One-Class Self Organizing Map (OCSOM). The acoustic signals of fuel injectors in different operational conditions were processed for feature extraction. Features from all the signals were used as input to the one-class classifiers. The one-class classifiers were trained only with healthy fuel injector conditions and compared with new experimental data which belonged to different operational conditions that were not included in the training set so as to contribute to generalization. The results present the effectiveness of one-class classifiers for detecting faults in fuel injectors.展开更多
<strong>Background:</strong> The implantation of the intraocular lens (IOL) is still subject to error and complication, as it can result in traumatic opening of the IOL leading to rupture of the posterior ...<strong>Background:</strong> The implantation of the intraocular lens (IOL) is still subject to error and complication, as it can result in traumatic opening of the IOL leading to rupture of the posterior capsule and zonular dialysis, it takes time to train paramedic teams to assemble such IOLs with the manual injectors. Moreover, there is a potential risk of comtamination and endophthalmitis as there is manipulation of the IOL and cartridge. The preloaded IOLs tend to reduce those unwanted results and may optimize the surgical time. <strong>Purpose:</strong> The aim of this study is to compare the effectiveness and implantation time between three injectors and three intraocular lenses, two pre-loaded and one conventional. <strong>Methodology:</strong> Videos of thirty patients undergoing cataract surgery from December 2019 to December 2020 at the Hospital Oftalmológico de Brasília (HOB), Brasília, Brazil were included in this observational, analytical retrospective study, non randomized. All patients had their surgeries recorded, from which the time of injection and opening of the intraocular lens (IOL) was extracted, 20 eyes were implanted with preloaded intraocular lens, and 10 eyes with conventional IOL implant. The patients were divided into three groups with similar eye characteristics. The first received the AutonoMe<sup>TM</sup> (CE) injector with the Clareon<span style="white-space:nowrap;"><sup>®</sup></span><span style="font-size:10px;"> </span><span style="white-space:nowrap;"><span style="color:#FFFFFF;font-family:Roboto, "white-space:normal;background-color:#D46399;"><span style="white-space:nowrap;"></span></span></span>IOL, the second the Isert<sup>TM</sup> injector (I) with the Hoya<span style="white-space:nowrap;"><sup><span style="white-space:nowrap;">®</span></sup></span> IOL, and the third was injected with Johnson & Johnson Platinum 1 Series injector used to deliver Sensar<span style="white-space:nowrap;"><sup><span style="white-space:nowrap;">®</span></sup></span> One AAB00 lens. The Welch test and Tukey’s Post Hoc test were used in the statistical analysis. <strong>Results:</strong> It was observed that there was a statistical significance regarding the presence of a haptic stuck (5 Clareon vs 0 Sensar and Hoya), between the mean opening time of the IOL optics Sensar One, Hoya and Clareon (25.00 vs 31.40 vs 11.70 s, p < 0.001) and between the total time (the injection time more the opening time of the IOL) in relation to Hoya and Clareon lenses (39.50 s vs 19.60 s, p < 0.001);the total time of the Sensar IOL was 31.30 s. The opening time of the IOL optics was significantly longer for the Sensar One and Hoya groups compared to Clareon group, and the total time of Hoya group was significantly longer compared to the total time of the Clareon group. <strong>Conclusion:</strong> The study demonstrated that the choice of injector and IOL set can significantly affect the total time of IOL implantation. However, there was no difference regarding complications and collateral damage depending on the set chosen for the implant.展开更多
Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. To facilitate this transformation, signific...Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. To facilitate this transformation, significantly extended design freedom and knowledge must be available in the early design stages. This paper presents a high-fidelity framework for design and optimization of the liquid swirl injectors that are widely used in aerospace propulsion and power-generation systems. The framework assembles a set of techniques, including Design Of Experiment(DOE), high-fidelity Large Eddy Simulations(LES), machine learning, Proper Orthogonal Decomposition(POD)-based Kriging surrogate modeling(emulation), inverse problem optimization, and uncertainty quantification. LES-based simulations can reveal detailed spatiotemporal evolution of flow structures and flame dynamics in a high-fidelity manner, and identify important injector design parameters according to their effects on propellant mixing, flame stabilization, and thermal protection.For a given a space of design parameters, DOE determines the number of design points to perform LES-based simulations. POD-based emulations, trained by the LES database, can effectively explore the design space and deduce an optimal group of design parameters in a turn-around time that is reduced by three orders of magnitude. The accuracy of the emulated results is validated, and the uncertainty of prediction is quantified. The proposed design methodology is expected to profoundly extend the knowledge base and reduce the cost for initial design stages.展开更多
Experimental observations together with theoretical analysis were conducted to investigate the break phenomenon and the corresponding mechanisms of self-pulsation for a liquid-centered swirl coaxial injector with rece...Experimental observations together with theoretical analysis were conducted to investigate the break phenomenon and the corresponding mechanisms of self-pulsation for a liquid-centered swirl coaxial injector with recess number of RN=1.Instantaneous spray images were obtained based on background light imaging technology with a high-speed camera.By dynamic analysis of the flow process of the liquid sheet in the recess chamber,a 1D self-pulsation theoretical model was established,and the self-sustaining mechanisms of self-pulsation were analyzed in depth.The results show that the increase of the momentum flux ratio will lead to the occurrence of the break phenomenon of self-pulsation for the injector with a larger recess length,and the frequency and intensity of self-pulsation before and after the break phenomenon differ significantly.The flow dynamics in the recess chamber sequentially transform from a periodic expansion-dominated flow to a stable flow,and then develop to a periodic contraction-dominated flow during the break process of self-pulsation.With the occurrence of self-pulsation before the break phenomenon,the liquid sheet has little effect on the pressure disturbance in the recess chamber.In contrast,with the occurrence of self-pulsation after the break phenomenon,the pressure disturbance is obviously affected by the liquid sheet.Based on the theoretical analysis model of self-pulsation,the self-pulsation frequency can be predicted.Furthermore,the self-sustaining mechanism of self-pulsation before and after the break phenomenon is preliminarily confirmed.The energy transfer between the gas-and liquid-phase is an important factor for maintaining the self-pulsation process.展开更多
To predict the effect of the liquid rocket engine combustion chamber conditions on the impingement spray, the conventional uncoupled spray model for impinging injectors is extended by considering the coupling of the j...To predict the effect of the liquid rocket engine combustion chamber conditions on the impingement spray, the conventional uncoupled spray model for impinging injectors is extended by considering the coupling of the jet impingement process and the ambient gas field. The new coupled model consists of the plain-orifice sub-model, the jet-jet impingement sub-model and the droplet collision sub-model. The parameters of the child droplet are determined with the jet-jet impingement sub-model using correlations about the liquid jet parameters and the chamber conditions.The overall model is benchmarked under various impingement angles, jet momentum and offcenter ratios. Agreement with the published experimental data validates the ability of the model to predict the key spray characteristics, such as the mass flux and mixture ratio distributions in quiescent air. Besides, impinging sprays under changing ambient pressure and non-uniform gas flow are investigated to explore the effect of liquid rocket engine chamber conditions. First, a transient impingement spray during engine start-up phase is simulated with prescribed pressure profile. The minimum average droplet diameter is achieved when the orifices work in cavitation state, and is about 30% smaller than the steady single phase state. Second, the effect of non-uniform gas flow produces off-center impingement and the rotated spray fan by 38°. The proposed model suggests more reasonable impingement spray characteristics than the uncoupled one and can be used as the first step in the complex simulation of coupling impingement spray and combustion in liquid rocket engines.展开更多
Five types of coaxial injectors were investigated experimentally using hot hydrogen-rich gas and oxygen-rich gas, which were respectively provided by a GH2/GO2 hydrogen-rich perburner and a GH2/GO2 oxygen-rich preburn...Five types of coaxial injectors were investigated experimentally using hot hydrogen-rich gas and oxygen-rich gas, which were respectively provided by a GH2/GO2 hydrogen-rich perburner and a GH2/GO2 oxygen-rich preburner. The injectors were the shear coaxial injector, the oxidizer post expansion coaxial injector, the fuel impinging coaxial injector, the central body coaxial injector, and the shear tri-coaxial injector. The characteristic velocity efficiency and the combustor＇s wall temperatures were obtained for different design parameters through the experiments. It can be con- cluded that angles of the oxidizer post expansion and the fuel impinging have little influence on the combustion performance and the wall temperatures. The contact area between fuel and oxidizer and the mass flow rate have significant impacts on the combustion performance. The shear tri-coaxial injector has the best combustion performance but also the highest wall temperatures among the five types of injectors.展开更多
Two sets of neutral beam injectors(NBI-1 and NBI-2) have been mounted on the EAST tokamak since 2014. NBI-1 and NBI-2 are co-direction and counter-direction, respectively. As with indepth physics and engineering study...Two sets of neutral beam injectors(NBI-1 and NBI-2) have been mounted on the EAST tokamak since 2014. NBI-1 and NBI-2 are co-direction and counter-direction, respectively. As with indepth physics and engineering study of EAST, the ability of long pulse beam injection should be required in the NBI system. For NBIs, the most important and difficult thing that should be overcome is heat removal capacity of heat loaded components for long-pulse beam extraction. In this article, the thermal state of the components of EAST NBI is investigated using water flow calorimetry and thermocouple temperatures. Results show that(1) operation parameters have an obvious influence on the heat deposited on the inner components of the beamline,(2) a suitable operation parameter can decrease the heat loading effectively and obtain longer beam pulse length, and(3) under the cooling water pressure of 0.25 MPa, the predicted maximum beam pulse length will be up to 260 s with 50 keV beam energy by a duty factor of 0.5. The results present that, in this regard, the EAST NBI-1 system has the ability of long-pulse beam injection.展开更多
Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact pro...Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.展开更多
The influences of the shear coaxial injector parameters on the combustion performance and the heat load of a combustor are studied numerically and experimentally. The injector parameters, including the ratio of the ox...The influences of the shear coaxial injector parameters on the combustion performance and the heat load of a combustor are studied numerically and experimentally. The injector parameters, including the ratio of the oxidizer pressure drop to the combustor pressure （DP ）, the velocity ratio of fuel to oxidizer （R V ）, the thickness （WO ）, and the recess （HO ） of the oxidizer injector post tip, the temperature of the hydrogen-rich gas （TH ） and the oxygen-rich gas （TO ）, are integrated by the orthogonal experimental design method to investigate the performance of the shear coaxial injector. The gaseous hydrogen/oxygen at ambient temperature （GH2 /GO2 ）, and the hot hydrogen-rich gas/oxygen-rich gas are used here. The length of the combustion （LC ）, the average temperatures of the combustor wall （TW ）, and the faceplate （TF ） are selected as the indicators. The tendencies of the influences of injector parameters on the combustion performance and the heat load of the combustor for the GH2 /GO2 case are similar to those in the hot propellants case. However, the combustion performance in the hot propellant case is better than that in the GH2/GO2 case, and the heat load of the combustor is also larger than that in the latter case.展开更多
The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP（Institute of Plasma Physics, Chinese Academy of Sciences）： one for the neutralbeam test stand and ...The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP（Institute of Plasma Physics, Chinese Academy of Sciences）： one for the neutralbeam test stand and two for the EAST neutral-beam injectors（NBI-1 and NBI-2, respectively）. Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 ke V was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.展开更多
A large-area high-power radio-frequency（RF） driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute（KAERI）. The RF ion source consists of a dr...A large-area high-power radio-frequency（RF） driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute（KAERI）. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.展开更多
In response to the increasing demand for hadron therapy facilities,significant efforts have been directed toward enhancing the performance of high-gradient and high-transmission injectors for light ion beams.For carbo...In response to the increasing demand for hadron therapy facilities,significant efforts have been directed toward enhancing the performance of high-gradient and high-transmission injectors for light ion beams.For carbon ion irradiations,which offer greater radiobiological efficiency in tumor treatment,recent research has focused on developing high-production sources of fully stripped C^(6+)ions and highly compact,high-frequency RFQ cavities.This study explores the design possibilities of a carbon ion acceleration section using 750 MHz Interdigital H-mode Drift Tube Linacs(IH-DTLs)as a high-efficiency solution for accelerating ions in the 5-10 MeV per nucleon energy range.A particle-tracking routine based on the TRAVEL code was developed to design the acceleration line through a tailored KONUS-type configuration.Three design solutions were proposed and compared,exploring different alternatives regarding the use of a MEBT to match the output beam phase space of the RFQ to the optics of the line,as well as varying considerations for magnetic systems to focus the beam.Additionally,the compatibility of the proposed solutions with the existing design of the carbon ion bent-linac for hadron therapy was assessed.展开更多
This study aims to reveal the influence of Local Momentum Ratio(LMR)on the combustion efficiency of an LOX/GCH4 pintle injector from the perspective of spray characteristics.Hot fire tests were conducted to establish ...This study aims to reveal the influence of Local Momentum Ratio(LMR)on the combustion efficiency of an LOX/GCH4 pintle injector from the perspective of spray characteristics.Hot fire tests were conducted to establish the relationship between combustion efficiency and LMR.The spray characteristics for different LMRs were simulated by the validated volume of fluid-to-discrete phase model method,taking into account the combustion chamber wall confinement.Subsequently,the difference in combustion efficiency was analyzed by comparing the spray simulation results of backpressure conditions similar to hot fire tests.The results indicate that combustion efficiency increased initially(LMR=1.12-1.64)and then decreased(LMR>1.64).Quantitative analysis revealed a linear correlation(R^(2)=0.95)between LMR and combustion efficiency within 1.12<LMR<1.64.As the LMR increased,the improvement in combustion efficiency was attributed to a wider spray distribution range and smaller droplet sizes.The area of the mantle recirculation zone that is detrimental to combustion decreased by approximately 38%,and the droplet size reduced from 37 to 16μm.This effectively enhanced both the mixing of the propellant and the evaporation process.When the LMR exceeded the critical value(1.64 in this study),the impingement of liquid oxygen on the combustion chamber wall was confirmed via overheating discoloration marks on the inner surface of combustion chamber's cylindrical section.The impingement of liquid oxygen on the combustion chamber wall increased the transport of liquid oxygen to the wall,directly reducing the mixing quality and combustion efficiency.The outcomes of this study provide the practical guidance for design and improvement in combustion efficiency of the pintle injector thrust chamber.展开更多
Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several ...Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several spatially and time- resolved non-intrusive optical techniques, such as OH planar laser induced fluorescence(PLIF), high speed imaging, and infrared imaging, are simultaneously employed to observe the OH radical concentration distribution, flame fluctuations, and temperature fields. The results demonstrate that the turbulent flow phenomenon of non-premixed flame exhibits a remarkable periodicity, and the mixing ratio becomes a crucial factor to influence the combustion flame length. The high speed and infrared images have a consistent temperature field trend. As for the OH-PLIF images, an intuitionistic local flame structure is revealed by single-shot instantaneous images. Furthermore, the means and standard deviations of OH radical intensity are acquired to provide statistical information regarding the flame, which may be helpful for validation of numerical simulations in future. Parameters of structure configurations, such as impinging angle and oxygen post thickness, play an important role in the reaction zone distribution. Based on a successful flame contour extraction method assembled with non-linear anisotropic diffusive filtering and variational level-set, it is possible to implement a fractal analysis to describe the fractal characteristics of the non-premixed flame contour. As a result, the flame front cannot be regarded as a fractal object. However, this turbulent process presents a self-similarity characteristic.展开更多
Let G be a finite group andНbe a Hartley set of G.In this paper,we prove the existence and conjugacy ofН-injectors of G and describe the characterization of injectors via radicals.As applications,some known results ...Let G be a finite group andНbe a Hartley set of G.In this paper,we prove the existence and conjugacy ofН-injectors of G and describe the characterization of injectors via radicals.As applications,some known results are directly followed.展开更多
This paper provides a review on sample injectors which are provided at SPring-8 Angstrom Compact free electron LAser(SACLA) for conducting serial measurement in a ‘diffract-before-destroy' scheme using an x-ray f...This paper provides a review on sample injectors which are provided at SPring-8 Angstrom Compact free electron LAser(SACLA) for conducting serial measurement in a ‘diffract-before-destroy' scheme using an x-ray free electron laser(XFEL). Versatile experimental platforms at SACLA are able to accept various types of injectors, among which liquidjet, droplet and viscous carrier injectors are frequently utilized. These injectors produce different forms of fluid targets such as a liquid filament with a diameter in the order of micrometer, micro-droplet synchronized to XFEL pulses, and slowly flowing column of highly viscous fluid with a rate below 1 μL min-1. Characteristics and applications of the injectors are described.展开更多
Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scannin...Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness.However,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread application.This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions.Preliminary corrections were explored through a combination of data processing analysis and numerical simulations.Furthermore,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability.Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method.Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions.Through the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.展开更多
Self-excited longitudinal combustion instabilities were investigated in a hypergolic liquid bipropellant combustor, which applied single dual-swirl coaxial injector. Hot-fire tests were conducted for four different in...Self-excited longitudinal combustion instabilities were investigated in a hypergolic liquid bipropellant combustor, which applied single dual-swirl coaxial injector. Hot-fire tests were conducted for four different injector geometries, while extensive tests on injection conditions were carried out for each injector geometry. The synchronous measurement of the pressure and heat release rate was applied, successfully capturing the process of the pressure and heat release rate enhanced coupling and developing into in-phase oscillation. By calculating Rayleigh index at the head and middle section of the chamber, it is shown that Rayleigh index of the middle section is even higher than that of the head, indicating a long heat release zone. When the combustion instability occurs, the pressure in propellant manifolds also oscillates with the same frequency and lags behind the oscillation in the combustor. Compared to the oscillation in the outer injector manifold, the oscillation in the inner injector manifold shows a higher correlation with that in the chamber in amplitude and phase. Based on numerical simulations of the multiphase cold flow inside the injector and combustion process in the chamber, it is found that injector geometries affect longitudinal combustion instability by changing spray cone angle. The spray with small cone angle is more sensitive to the modulation of longitudinal pressure wave in combustion simulations, which is more likely to excite the longitudinal combustion instability. Meanwhile, the combustion instability may be related to the pulsating coherent structure generated by the spray fluctuation, which is determined by injection conditions. Besides, a positive feedback closed-loop system associated with the active fluctuation and passive oscillation of the spray is believed to excite and sustain the longitudinal combustion instability.展开更多
基金supported by the Hundred-person Program of Chinese Academy of Sciences and the National Natural Science Foundation of China(No.11905074).
文摘Electron beam injectors are pivotal components of large-scale scientific instruments,such as synchrotron radiation sources,free-electron lasers,and electron-positron colliders.The quality of the electron beam produced by the injector critically influences the performance of the entire accelerator-based scientific research apparatus.The injectors of such facilities usually use photocathode and thermionic-cathode electron guns.Although the photocathode injector can produce electron beams of excellent quality,its associated laser system is massive and intricate.The thermionic-cathode electron gun,especially the gridded electron gun injector,has a simple structure capable of generating numerous electron beams.However,its emittance is typically high.In this study,methods to reduce beam emittance are explored through a comprehensive analysis of various grid structures and preliminary design results,examining the evolution of beam phase space at different grid positions.An optimization method for reducing the emittance of a gridded thermionic-cathode electron gun is proposed through theoretical derivation,electromagnetic-field simulation,and beam-dynamics simulation.A 50%reduction in emittance was achieved for a 50 keV,1.7 A electron gun,laying the foundation for the subsequent design of a high-current,low-emittance injector.
基金the National Natural Science Foundation of China (Nos. 51806057, 52005152 and 12042211)the Natural Science Foundation of Hebei, China (Nos. E2019202460 and E2019202451)+2 种基金Tianjin Science and Technology Project, China (No. 19YFZCSF00850)the Key Research Program Projects of Hebei Province, China (No. 19274502D)the Industrial Technology Research of Hebei University of Technology, China (No. ZBYJY201902)
文摘Combustion instability is a very important issue in the development of the propulsion systems used in aerospace. It is very important to associate the high frequency combustion instabilities with the acoustic characteristics of the combustion chamber. In this paper, the effects of various baffle injectors which were installed on the injector faceplate on the first-order tangential acoustic mode were investigated theoretically and experimentally. The effects of the gap between adjacent injectors on the first-order tangential acoustic mode in a cylindrical chamber were considered. The acoustic admittance of the injectors was derived. The results showed that the amplitude and frequency of the first-order tangential acoustic mode increase with the increase in the gap between adjacent injectors, but decrease with the increase in the number and height of the baffles.The baffle injectors have a greater influence on the amplitude and frequency of the first-order tangential acoustic mode than the baffle blades.
文摘Fuel injectors are considered as an important component of combustion engines. Operational weakness can possibly lead to the complete machine malfunction, decreasing reliability and leading to loss of production. To overcome these circumstances, various condition monitoring techniques can be applied. The application of acoustic signals is common in the field of fault diagnosis of rotating machinery. Advanced signal processing is utilized for the construction of features that are specialized in detecting fuel injector faults. A performance comparison between novelty detection algorithms in the form of one-class classifiers is presented. The one-class classifiers that were tested included One-Class Support Vector Machine (OCSVM) and One-Class Self Organizing Map (OCSOM). The acoustic signals of fuel injectors in different operational conditions were processed for feature extraction. Features from all the signals were used as input to the one-class classifiers. The one-class classifiers were trained only with healthy fuel injector conditions and compared with new experimental data which belonged to different operational conditions that were not included in the training set so as to contribute to generalization. The results present the effectiveness of one-class classifiers for detecting faults in fuel injectors.
文摘<strong>Background:</strong> The implantation of the intraocular lens (IOL) is still subject to error and complication, as it can result in traumatic opening of the IOL leading to rupture of the posterior capsule and zonular dialysis, it takes time to train paramedic teams to assemble such IOLs with the manual injectors. Moreover, there is a potential risk of comtamination and endophthalmitis as there is manipulation of the IOL and cartridge. The preloaded IOLs tend to reduce those unwanted results and may optimize the surgical time. <strong>Purpose:</strong> The aim of this study is to compare the effectiveness and implantation time between three injectors and three intraocular lenses, two pre-loaded and one conventional. <strong>Methodology:</strong> Videos of thirty patients undergoing cataract surgery from December 2019 to December 2020 at the Hospital Oftalmológico de Brasília (HOB), Brasília, Brazil were included in this observational, analytical retrospective study, non randomized. All patients had their surgeries recorded, from which the time of injection and opening of the intraocular lens (IOL) was extracted, 20 eyes were implanted with preloaded intraocular lens, and 10 eyes with conventional IOL implant. The patients were divided into three groups with similar eye characteristics. The first received the AutonoMe<sup>TM</sup> (CE) injector with the Clareon<span style="white-space:nowrap;"><sup>®</sup></span><span style="font-size:10px;"> </span><span style="white-space:nowrap;"><span style="color:#FFFFFF;font-family:Roboto, "white-space:normal;background-color:#D46399;"><span style="white-space:nowrap;"></span></span></span>IOL, the second the Isert<sup>TM</sup> injector (I) with the Hoya<span style="white-space:nowrap;"><sup><span style="white-space:nowrap;">®</span></sup></span> IOL, and the third was injected with Johnson & Johnson Platinum 1 Series injector used to deliver Sensar<span style="white-space:nowrap;"><sup><span style="white-space:nowrap;">®</span></sup></span> One AAB00 lens. The Welch test and Tukey’s Post Hoc test were used in the statistical analysis. <strong>Results:</strong> It was observed that there was a statistical significance regarding the presence of a haptic stuck (5 Clareon vs 0 Sensar and Hoya), between the mean opening time of the IOL optics Sensar One, Hoya and Clareon (25.00 vs 31.40 vs 11.70 s, p < 0.001) and between the total time (the injection time more the opening time of the IOL) in relation to Hoya and Clareon lenses (39.50 s vs 19.60 s, p < 0.001);the total time of the Sensar IOL was 31.30 s. The opening time of the IOL optics was significantly longer for the Sensar One and Hoya groups compared to Clareon group, and the total time of Hoya group was significantly longer compared to the total time of the Clareon group. <strong>Conclusion:</strong> The study demonstrated that the choice of injector and IOL set can significantly affect the total time of IOL implantation. However, there was no difference regarding complications and collateral damage depending on the set chosen for the implant.
基金sponsored by the William RT Oakes Endowment of the Georgia Institute of Technology
文摘Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. To facilitate this transformation, significantly extended design freedom and knowledge must be available in the early design stages. This paper presents a high-fidelity framework for design and optimization of the liquid swirl injectors that are widely used in aerospace propulsion and power-generation systems. The framework assembles a set of techniques, including Design Of Experiment(DOE), high-fidelity Large Eddy Simulations(LES), machine learning, Proper Orthogonal Decomposition(POD)-based Kriging surrogate modeling(emulation), inverse problem optimization, and uncertainty quantification. LES-based simulations can reveal detailed spatiotemporal evolution of flow structures and flame dynamics in a high-fidelity manner, and identify important injector design parameters according to their effects on propellant mixing, flame stabilization, and thermal protection.For a given a space of design parameters, DOE determines the number of design points to perform LES-based simulations. POD-based emulations, trained by the LES database, can effectively explore the design space and deduce an optimal group of design parameters in a turn-around time that is reduced by three orders of magnitude. The accuracy of the emulated results is validated, and the uncertainty of prediction is quantified. The proposed design methodology is expected to profoundly extend the knowledge base and reduce the cost for initial design stages.
基金supported by the National Natural Science Foundation of China(No.11872375)the National Science Foundation for Young Scientists of China(Nos.11802323,11902351,and 12102462)。
文摘Experimental observations together with theoretical analysis were conducted to investigate the break phenomenon and the corresponding mechanisms of self-pulsation for a liquid-centered swirl coaxial injector with recess number of RN=1.Instantaneous spray images were obtained based on background light imaging technology with a high-speed camera.By dynamic analysis of the flow process of the liquid sheet in the recess chamber,a 1D self-pulsation theoretical model was established,and the self-sustaining mechanisms of self-pulsation were analyzed in depth.The results show that the increase of the momentum flux ratio will lead to the occurrence of the break phenomenon of self-pulsation for the injector with a larger recess length,and the frequency and intensity of self-pulsation before and after the break phenomenon differ significantly.The flow dynamics in the recess chamber sequentially transform from a periodic expansion-dominated flow to a stable flow,and then develop to a periodic contraction-dominated flow during the break process of self-pulsation.With the occurrence of self-pulsation before the break phenomenon,the liquid sheet has little effect on the pressure disturbance in the recess chamber.In contrast,with the occurrence of self-pulsation after the break phenomenon,the pressure disturbance is obviously affected by the liquid sheet.Based on the theoretical analysis model of self-pulsation,the self-pulsation frequency can be predicted.Furthermore,the self-sustaining mechanism of self-pulsation before and after the break phenomenon is preliminarily confirmed.The energy transfer between the gas-and liquid-phase is an important factor for maintaining the self-pulsation process.
文摘To predict the effect of the liquid rocket engine combustion chamber conditions on the impingement spray, the conventional uncoupled spray model for impinging injectors is extended by considering the coupling of the jet impingement process and the ambient gas field. The new coupled model consists of the plain-orifice sub-model, the jet-jet impingement sub-model and the droplet collision sub-model. The parameters of the child droplet are determined with the jet-jet impingement sub-model using correlations about the liquid jet parameters and the chamber conditions.The overall model is benchmarked under various impingement angles, jet momentum and offcenter ratios. Agreement with the published experimental data validates the ability of the model to predict the key spray characteristics, such as the mass flux and mixture ratio distributions in quiescent air. Besides, impinging sprays under changing ambient pressure and non-uniform gas flow are investigated to explore the effect of liquid rocket engine chamber conditions. First, a transient impingement spray during engine start-up phase is simulated with prescribed pressure profile. The minimum average droplet diameter is achieved when the orifices work in cavitation state, and is about 30% smaller than the steady single phase state. Second, the effect of non-uniform gas flow produces off-center impingement and the rotated spray fan by 38°. The proposed model suggests more reasonable impingement spray characteristics than the uncoupled one and can be used as the first step in the complex simulation of coupling impingement spray and combustion in liquid rocket engines.
基金supported by the National High Technology Research and Development Program of China (No.2009AA702504)
文摘Five types of coaxial injectors were investigated experimentally using hot hydrogen-rich gas and oxygen-rich gas, which were respectively provided by a GH2/GO2 hydrogen-rich perburner and a GH2/GO2 oxygen-rich preburner. The injectors were the shear coaxial injector, the oxidizer post expansion coaxial injector, the fuel impinging coaxial injector, the central body coaxial injector, and the shear tri-coaxial injector. The characteristic velocity efficiency and the combustor＇s wall temperatures were obtained for different design parameters through the experiments. It can be con- cluded that angles of the oxidizer post expansion and the fuel impinging have little influence on the combustion performance and the wall temperatures. The contact area between fuel and oxidizer and the mass flow rate have significant impacts on the combustion performance. The shear tri-coaxial injector has the best combustion performance but also the highest wall temperatures among the five types of injectors.
文摘Two sets of neutral beam injectors(NBI-1 and NBI-2) have been mounted on the EAST tokamak since 2014. NBI-1 and NBI-2 are co-direction and counter-direction, respectively. As with indepth physics and engineering study of EAST, the ability of long pulse beam injection should be required in the NBI system. For NBIs, the most important and difficult thing that should be overcome is heat removal capacity of heat loaded components for long-pulse beam extraction. In this article, the thermal state of the components of EAST NBI is investigated using water flow calorimetry and thermocouple temperatures. Results show that(1) operation parameters have an obvious influence on the heat deposited on the inner components of the beamline,(2) a suitable operation parameter can decrease the heat loading effectively and obtain longer beam pulse length, and(3) under the cooling water pressure of 0.25 MPa, the predicted maximum beam pulse length will be up to 260 s with 50 keV beam energy by a duty factor of 0.5. The results present that, in this regard, the EAST NBI-1 system has the ability of long-pulse beam injection.
基金This work was supported by National Natural Science Foundation of China(No.12222513).
文摘Radio frequency quadrupoles(RFQs),which are crucial components of proton injectors,significantly affect the performance of proton accelerator facilities.An RFQ with a high frequency of 714 MHz dedicated to compact proton injectors for medi-cal applications is designed in this study.The RFQ is designed to accelerate proton beams from 50 keV to 4 MeV within a short length of 2 m and can be matched closely with the downstream drift tube linac to capture more particles through a preliminary optimization.To develop an advanced RFQ,challenging techniques,including fabrication and tuning method,must be evaluated and verified using a prototype.An aluminium prototype is derived from the conceptual design of the RFQ and then redesigned to confirm the radio frequency performance,fabrication procedure,and feasibility of the tuning algorithm.Eventually,a new tuning algorithm based on the response matrix and least-squares method is developed,which yields favorable results based on the prototype,i.e.,the errors of the dipole and quadrupole components reduced to a low level after several tuning iterations.Benefiting from the conceptual design and techniques obtained from the prototype,the formal mechanical design of the 2-m RFQ is ready for the next manufacturing step.
基金Project supported by the National High Technology Research and Development Program of China (Grant No. 2009702504)
文摘The influences of the shear coaxial injector parameters on the combustion performance and the heat load of a combustor are studied numerically and experimentally. The injector parameters, including the ratio of the oxidizer pressure drop to the combustor pressure （DP ）, the velocity ratio of fuel to oxidizer （R V ）, the thickness （WO ）, and the recess （HO ） of the oxidizer injector post tip, the temperature of the hydrogen-rich gas （TH ） and the oxygen-rich gas （TO ）, are integrated by the orthogonal experimental design method to investigate the performance of the shear coaxial injector. The gaseous hydrogen/oxygen at ambient temperature （GH2 /GO2 ）, and the hot hydrogen-rich gas/oxygen-rich gas are used here. The length of the combustion （LC ）, the average temperatures of the combustor wall （TW ）, and the faceplate （TF ） are selected as the indicators. The tendencies of the influences of injector parameters on the combustion performance and the heat load of the combustor for the GH2 /GO2 case are similar to those in the hot propellants case. However, the combustion performance in the hot propellant case is better than that in the GH2/GO2 case, and the heat load of the combustor is also larger than that in the latter case.
基金supported by the National Magnetic Confinement Fusion Science Program of China(No.2013GB101003)National Natural Science Foundation of China(No.11505225)Foundation of ASIPP(No.DSJJ-15-GC03)
文摘The long-pulse power-supply system equipped for the 4 MW beam-power ion source is comprised of three units at ASIPP（Institute of Plasma Physics, Chinese Academy of Sciences）： one for the neutralbeam test stand and two for the EAST neutral-beam injectors（NBI-1 and NBI-2, respectively）. Each power supply system consists of two low voltage and high current DC power supplies for plasma generation of the ion source, and two high voltage and high current DC power supplies for the accelerator grid system. The operation range of the NB power supply is about 80 percent of the design value, which is the safe and stable operation range. At the neutral-beam test stand, a hydrogen ion beam with a beam pulse of 150 s, beam power of 1.5 MW and beam energy of 50 ke V was achieved during the long-pulse testing experiments. The result shows that the power-supply system meets the requirements of the EAST-NBIs fully and lays a basis for achieving plasma heating.
基金supported by the Ministry of Science,ICT and Future Planning of the Republic of Korea under the ITER Technology R&D ProgramNational R&D Program Through the National Research Foundation of Korea(NRF)Funded by the Ministry of Science,ICT&Future Planning(NRF-2014M1A7A1A03045372)
文摘A large-area high-power radio-frequency（RF） driven ion source was developed for positive and negative neutral beam injectors at the Korea Atomic Energy Research Institute（KAERI）. The RF ion source consists of a driver region, including a helical antenna and a discharge chamber, and an expansion region. RF power can be transferred at up to 10 kW with a fixed frequency of 2 MHz through an optimized RF matching system. An actively water-cooled Faraday shield is located inside the driver region of the ion source for the stable and steady-state operations of high-power RF discharge. Plasma ignition of the ion source is initiated by the injection of argongas without a starter-filament heating, and the argon-gas is then slowly exchanged by the injection of hydrogen-gas to produce pure hydrogen plasmas. The uniformities of the plasma parameter,such as a plasma density and an electron temperature, are measured at the lowest area of the driver region using two RF-compensated electrostatic probes along the direction of the shortand long-dimensions of the driver region. The plasma parameters will be compared with those obtained at the lowest area of the expansion bucket to analyze the plasma expansion properties from the driver region to the expansion region.
基金Project co-funded by European Union in the context of the precommercial public procurement of RD services managed by CDTI E.P.Eco-funded by the European Regional Development Fund(ERDF)as part of the project for the development of a Compact Linear Accelerator for Hadrontherapy,Exp.CPP 03/2023 AB(DCCPI/OCPI)。
文摘In response to the increasing demand for hadron therapy facilities,significant efforts have been directed toward enhancing the performance of high-gradient and high-transmission injectors for light ion beams.For carbon ion irradiations,which offer greater radiobiological efficiency in tumor treatment,recent research has focused on developing high-production sources of fully stripped C^(6+)ions and highly compact,high-frequency RFQ cavities.This study explores the design possibilities of a carbon ion acceleration section using 750 MHz Interdigital H-mode Drift Tube Linacs(IH-DTLs)as a high-efficiency solution for accelerating ions in the 5-10 MeV per nucleon energy range.A particle-tracking routine based on the TRAVEL code was developed to design the acceleration line through a tailored KONUS-type configuration.Three design solutions were proposed and compared,exploring different alternatives regarding the use of a MEBT to match the output beam phase space of the RFQ to the optics of the line,as well as varying considerations for magnetic systems to focus the beam.Additionally,the compatibility of the proposed solutions with the existing design of the carbon ion bent-linac for hadron therapy was assessed.
基金co-supported by the National Science Foundation Project,China(No.2019-JCJQ-ZQ-019)the National Natural Science Foundation of China(Nos.52476141 and T2221002)。
文摘This study aims to reveal the influence of Local Momentum Ratio(LMR)on the combustion efficiency of an LOX/GCH4 pintle injector from the perspective of spray characteristics.Hot fire tests were conducted to establish the relationship between combustion efficiency and LMR.The spray characteristics for different LMRs were simulated by the validated volume of fluid-to-discrete phase model method,taking into account the combustion chamber wall confinement.Subsequently,the difference in combustion efficiency was analyzed by comparing the spray simulation results of backpressure conditions similar to hot fire tests.The results indicate that combustion efficiency increased initially(LMR=1.12-1.64)and then decreased(LMR>1.64).Quantitative analysis revealed a linear correlation(R^(2)=0.95)between LMR and combustion efficiency within 1.12<LMR<1.64.As the LMR increased,the improvement in combustion efficiency was attributed to a wider spray distribution range and smaller droplet sizes.The area of the mantle recirculation zone that is detrimental to combustion decreased by approximately 38%,and the droplet size reduced from 37 to 16μm.This effectively enhanced both the mixing of the propellant and the evaporation process.When the LMR exceeded the critical value(1.64 in this study),the impingement of liquid oxygen on the combustion chamber wall was confirmed via overheating discoloration marks on the inner surface of combustion chamber's cylindrical section.The impingement of liquid oxygen on the combustion chamber wall increased the transport of liquid oxygen to the wall,directly reducing the mixing quality and combustion efficiency.The outcomes of this study provide the practical guidance for design and improvement in combustion efficiency of the pintle injector thrust chamber.
文摘Single-element combustor experiments are conducted for three shear coaxial geometry configuration injectors by using gaseous oxygen and gaseous hydrogen(GO2/GH2) as propellants. During the combustion process, several spatially and time- resolved non-intrusive optical techniques, such as OH planar laser induced fluorescence(PLIF), high speed imaging, and infrared imaging, are simultaneously employed to observe the OH radical concentration distribution, flame fluctuations, and temperature fields. The results demonstrate that the turbulent flow phenomenon of non-premixed flame exhibits a remarkable periodicity, and the mixing ratio becomes a crucial factor to influence the combustion flame length. The high speed and infrared images have a consistent temperature field trend. As for the OH-PLIF images, an intuitionistic local flame structure is revealed by single-shot instantaneous images. Furthermore, the means and standard deviations of OH radical intensity are acquired to provide statistical information regarding the flame, which may be helpful for validation of numerical simulations in future. Parameters of structure configurations, such as impinging angle and oxygen post thickness, play an important role in the reaction zone distribution. Based on a successful flame contour extraction method assembled with non-linear anisotropic diffusive filtering and variational level-set, it is possible to implement a fractal analysis to describe the fractal characteristics of the non-premixed flame contour. As a result, the flame front cannot be regarded as a fractal object. However, this turbulent process presents a self-similarity characteristic.
文摘Let G be a finite group andНbe a Hartley set of G.In this paper,we prove the existence and conjugacy ofН-injectors of G and describe the characterization of injectors via radicals.As applications,some known results are directly followed.
基金supported by the X-ray FreeElectron Laser Priority Strategy Program (MEXT)JSPS KAKENHI Grant Number 15K05407
文摘This paper provides a review on sample injectors which are provided at SPring-8 Angstrom Compact free electron LAser(SACLA) for conducting serial measurement in a ‘diffract-before-destroy' scheme using an x-ray free electron laser(XFEL). Versatile experimental platforms at SACLA are able to accept various types of injectors, among which liquidjet, droplet and viscous carrier injectors are frequently utilized. These injectors produce different forms of fluid targets such as a liquid filament with a diameter in the order of micrometer, micro-droplet synchronized to XFEL pulses, and slowly flowing column of highly viscous fluid with a rate below 1 μL min-1. Characteristics and applications of the injectors are described.
基金supported by the National Natural Science Foundation of China(Nos.12341501 and 11905074)。
文摘Precise transverse emittance assessment in electron beams is crucial for advancing high-brightness beam injectors.As opposed to intricate methodologies that use specialized devices,quadrupole focusing strength scanning(Q-scanning)techniques offer notable advantages for various injectors owing to their inherent convenience and cost-effectiveness.However,their stringent approximation conditions lead to inevitable errors in practical operation,thereby limiting their widespread application.This study addressed these challenges by revisiting the analytical derivation procedure and investigating the effects of the underlying approximation conditions.Preliminary corrections were explored through a combination of data processing analysis and numerical simulations.Furthermore,based on theoretical derivations,virtual measurements using beam dynamics calculations were employed to evaluate the correction reliability.Subsequent experimental validations were performed at the Huazhong University of Science and Technology injector to verify the effectiveness of the proposed compensation method.Both the virtual and experimental results confirm the feasibility and reliability of the enhanced Q-scanning-based diagnosis for transverse emittance in typical beam injectors operating under common conditions.Through the integration of these corrections and compensations,enhanced Q-scanning-based techniques emerge as promising alternatives to traditional emittance diagnosis methods.
基金support from the National Natural Science Foundation of China(No.12002386).
文摘Self-excited longitudinal combustion instabilities were investigated in a hypergolic liquid bipropellant combustor, which applied single dual-swirl coaxial injector. Hot-fire tests were conducted for four different injector geometries, while extensive tests on injection conditions were carried out for each injector geometry. The synchronous measurement of the pressure and heat release rate was applied, successfully capturing the process of the pressure and heat release rate enhanced coupling and developing into in-phase oscillation. By calculating Rayleigh index at the head and middle section of the chamber, it is shown that Rayleigh index of the middle section is even higher than that of the head, indicating a long heat release zone. When the combustion instability occurs, the pressure in propellant manifolds also oscillates with the same frequency and lags behind the oscillation in the combustor. Compared to the oscillation in the outer injector manifold, the oscillation in the inner injector manifold shows a higher correlation with that in the chamber in amplitude and phase. Based on numerical simulations of the multiphase cold flow inside the injector and combustion process in the chamber, it is found that injector geometries affect longitudinal combustion instability by changing spray cone angle. The spray with small cone angle is more sensitive to the modulation of longitudinal pressure wave in combustion simulations, which is more likely to excite the longitudinal combustion instability. Meanwhile, the combustion instability may be related to the pulsating coherent structure generated by the spray fluctuation, which is determined by injection conditions. Besides, a positive feedback closed-loop system associated with the active fluctuation and passive oscillation of the spray is believed to excite and sustain the longitudinal combustion instability.
