To promote the fuel utilization efficiency of IC engine, an approach was proposed for IC engine coolant energy recovery based on low-temperature organic Rankine cycle(ORC). The ORC system uses IC engine coolant as hea...To promote the fuel utilization efficiency of IC engine, an approach was proposed for IC engine coolant energy recovery based on low-temperature organic Rankine cycle(ORC). The ORC system uses IC engine coolant as heat source, and it is coupled to the IC engine cooling system. After various kinds of organic working media were compared, R124 was selected as the ORC working medium. According to IC engine operating conditions and coolant energy characteristics, the major parameters of ORC system were preliminary designed. Then, the effects of various parameters on cycle performance and recovery potential of coolant energy were analyzed via cycle process calculation. The results indicate that cycle efficiency is mainly influenced by the working pressure of ORC, while the maximum working pressure is limited by IC engine coolant temperature. At the same working pressure, cycle efficiency is hardly affected by both the mass flow rate and temperature of working medium. When the bottom cycle working pressure arrives at the maximum allowable value of 1.6 MPa, the fuel utilization efficiency of IC engine could be improved by 12.1%.All these demonstrate that this low-temperature ORC is a useful energy-saving technology for IC engine.展开更多
Based on the theory of thermal radiation,a contact type optical fiber pyrometer applied in IC engine is put forward.It is composed of three parts:a blackbody probe,optical system,electrical process system.The key tech...Based on the theory of thermal radiation,a contact type optical fiber pyrometer applied in IC engine is put forward.It is composed of three parts:a blackbody probe,optical system,electrical process system.The key technology of design is discussed.Experiment is given to prove that the pyrometer has much higher responsive speed,distinguishability and much longer running life than other pyrometers.展开更多
In this study, combustion of methane was simulated using four kinetic models of methane in CHEMKIN 4.1.1 for 0-D closed internal combustion （IC） engine reactor. Two detailed （GRIMECH3.0 ＆ UBC MECH2.0） and two red...In this study, combustion of methane was simulated using four kinetic models of methane in CHEMKIN 4.1.1 for 0-D closed internal combustion （IC） engine reactor. Two detailed （GRIMECH3.0 ＆ UBC MECH2.0） and two reduced （One step ＆ Four steps） models were examined for various IC engine designs. The detailed models （GRIMECH3.0, ＆ UBC MECH2.0） and 4-step models successfully predicted the combustion while global model was unable to predict any combustion reaction. This study illustrated that the detailed model showed good concordances in the prediction of chamber pressure, temperature and major combustion species profiles. The detailed models also exhibited the capabilities to predict the pollutants formation in an IC engine while the reduced schemes showed failure in the prediction of pollutants emissions. Although, there are discrepancies among the profiles of four considered model, the detailed models （GRIMECH3.0 ＆ UBC MECH2.0） produced the acceptable agreement in the species prediction and formation of pollutants.展开更多
With the intensifying competition in the integrated circuit(IC)industry,the high turnover rate of integrated circuit engineers has become a prominent issue affecting the technological continuity of high-precision,spec...With the intensifying competition in the integrated circuit(IC)industry,the high turnover rate of integrated circuit engineers has become a prominent issue affecting the technological continuity of high-precision,specialized,and innovative enterprises.As a representative of such enterprises,JL Technology has faced challenges to its R&D efficiency due to talent loss in recent years.This study takes this enterprise as a case to explore feasible paths to reduce turnover rates through optimizing training and career development systems.The research designs a method combining learning maps and talent maps,utilizes a competency model to clarify the direction for engineers’skill improvement,implements talent classification management using a nine-grid model,and achieves personalized training through Individual Development Plans(IDPs).Analysis of the enterprise’s historical data reveals that the main reasons for turnover are unclear career development paths and insufficient resources for skill improvement.After pilot implementation,the turnover rate in core departments decreased by 12%,and employee satisfaction with training increased by 24%.The results indicate that matching systematic talent reviews with dynamic learning resources can effectively enhance engineers’sense of belonging.This study provides a set of highly operational management tools for small and medium-sized high-precision,specialized,and innovative technology enterprises,verifies their applicability in such enterprises,and offers replicable experiences for similar enterprises to optimize their talent strategies[1].展开更多
The health monitoring has been studied to ensure integrity of design of engine structure by detection,quantification,and prediction of damages.Early detection of faults may allow the downtime of maintenance to be resc...The health monitoring has been studied to ensure integrity of design of engine structure by detection,quantification,and prediction of damages.Early detection of faults may allow the downtime of maintenance to be rescheduled,thus preventing sudden shutdown of machines.In cylinder pressure developed,vibrations and noise emissions data provide a rich source of information about condition of engines.Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue.The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines.The effects of changing various fuel injection parameters was analyzed.Scope of using non-intrusive technique has been analyzed by changing locations of microphone.Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up.Various frequency ranges of contributing noise and vibration sources were identified.Time-Frequency analysis showed the onset of various cyclic.Based on the identification of various frequency bands,it is possible to device suitable filters in order to extract more information.展开更多
In this study,we report an analysis of cylinder head vibration signals at a steady engine speed using short-time Fourier transform(STFT).Three popular time-frequency analysis techniques,i.e.,STFT,analytic wavelet tran...In this study,we report an analysis of cylinder head vibration signals at a steady engine speed using short-time Fourier transform(STFT).Three popular time-frequency analysis techniques,i.e.,STFT,analytic wavelet transform(AWT) and S transform(ST),have been examined.AWT and ST are often applied in engine signal analyses.In particular,an AWT expression in terms of the quality factor Q and an analytical relationship between ST and AWT have been derived.The time-frequency resolution of a Gaussian function windowed STFT was studied via numerical simulation.Based on the simulation,the empirical limits for the lowest distinguishable frequency as well as the time and frequency resolutions were determined.These can provide insights for window width selection,spectrogram interpretation and artifact identification.Gaussian function windowed STFTs were applied to some cylinder head vibration signals.The spectrograms of the same signals from ST and AWT were also determined for comparison.The results indicate that the uniform resolution feature of STFT is not necessarily a disadvantage for time-frequency analysis of vibration signals when the engine is in stationary state because it can more accurately localize the frequency components excited by transient excitations without much loss of time resolution.展开更多
Turbochargers have been known in compression ignition engines for power generation.Recent trends in power generation through gas cycles have recorded successes via turbochargers application in spark ignition engines a...Turbochargers have been known in compression ignition engines for power generation.Recent trends in power generation through gas cycles have recorded successes via turbochargers application in spark ignition engines as well.When power cycles are turbocharged,there is a general expectation of a higher power and performance output from the cycle as compared to when they are naturally aspirated.This research was conducted to estimate the thermodynamic properties of a spark ignition engine power generating system when it is both naturally aspirated and when the same system is turbocharged to 2.5 times the amount of air in natural aspiration.Octane fuel was employed for petrol approximation during this study.The system process was broken down into stages of charging between natural aspiration and turbocharged;thus MATLAB program was applied to model the system for the case of natural aspiration and turbocharging with no increase in fuel supply.The results were used for both analyses and comparison which showed that the system generates slightly more power with turbocharging at 0%increase in fuel consumption.The natural aspiration achieved values are 2.8232 kJ/mol and 55.26%for output and efficiency respectively,while the turbocharged engine produced optimal values of 2.8833 kJ/mol and 56.51%for output and efficiency.The air fuel ratio by mole for the turbocharged engine was 145.18:1,which shows a greater fuel economy of 59%as compared to the 59.5:1 A/F(air/fuel)ratio of the naturally aspirated engine.展开更多
This paper presents an application of adaptive neural network model-based predictive control (MPC) to the air-fuel ratio of an engine simulation. A multi-layer perceptron (MLP) neural network is trained using two on-l...This paper presents an application of adaptive neural network model-based predictive control (MPC) to the air-fuel ratio of an engine simulation. A multi-layer perceptron (MLP) neural network is trained using two on-line training algorithms: a back propagation algorithm and a recursive least squares (RLS) algorithm. It is used to model parameter uncertainties in the nonlinear dynamics of internal combustion (IC) engines. Based on the adaptive model, an MPC strategy for controlling air-fuel ratio is realized, and its control performance compared with that of a traditional PI controller. A reduced Hessian method, a newly developed sequential quadratic programming (SQP) method for solving nonlinear programming (NLP) problems, is implemented to speed up nonlinear optimization in the MPC. Keywords Air-fuel ratio control - IC engine - adaptive neural networks - nonlinear programming - model predictive control Shi-Wei Wang PhD student, Liverpool John Moores University; MSc in Control Systems, University of Sheffield, 2003; BEng in Automatic Technology, Jilin University, 2000; Current research interests automotive engine control, model predictive control, sliding mode control, neural networks.Ding-Li Yu obtained B.Eng from Harbin Civil Engineering College, Harbin, China in 1981, M.Sc from Jilin University of Technology, Changchun, China in 1986 and PhD from Coventry University, U.K. in 1995, all in control engineering. He is currently a Reader in Process Control at Liverpool John Moores University, U.K. His current research interests are in process control, engine control, fault detection and adaptive neural nets. He is a member of SAFEPROCESS TC in IFAC and an associate editor of the IJMIC and the IJISS.展开更多
Proprietary(or semi-proprietary)protocols are widely adopted in industrial control systems(ICSs).Inferring protocol format by reverse engineering is important for many network security applications,e.g.,program tests ...Proprietary(or semi-proprietary)protocols are widely adopted in industrial control systems(ICSs).Inferring protocol format by reverse engineering is important for many network security applications,e.g.,program tests and intrusion detection.Conventional protocol reverse engineering methods have been proposed which are considered time-consuming,tedious,and error-prone.Recently,automatical protocol reverse engineering methods have been proposed which are,however,neither effective in handling binary-based ICS protocols based on network traffic analysis nor accurate in extracting protocol fields from protocol implementations.In this paper,we present a framework called the industrial control system protocol reverse engineering framework(ICSPRF)that aims to extract ICS protocol fields with high accuracy.ICSPRF is based on the key insight that an individual field in a message is typically handled in the same execution context,e.g.,basic block(BBL)group.As a result,by monitoring program execution,we can collect the tainted data information processed in every BBL group in the execution trace and cluster it to derive the protocol format.We evaluate our approach with six open-source ICS protocol implementations.The results show that ICSPRF can identify individual protocol fields with high accuracy(on average a 94.3%match ratio).ICSPRF also has a low coarse-grained and overly fine-grained match ratio.For the same metric,ICSPRF is more accurate than AutoFormat(88.5%for all evaluated protocols and 80.0%for binary-based protocols).展开更多
Ammonia(NH_(3))is emerging as a potential favoured fuel for longer range decarbonised heavy transport,particularly in the marine sector,predominantly due to highly favourable characteristics as an effective hydrogen c...Ammonia(NH_(3))is emerging as a potential favoured fuel for longer range decarbonised heavy transport,particularly in the marine sector,predominantly due to highly favourable characteristics as an effective hydrogen carrier.This is despite generally unfavourable combustion and toxicity attributes,restricting end use to applications where robust health and safety protocols can always be upheld.In the currently reported work,a spark ignited thermodynamic single cylinder research engine equipped with gasoline direct injection was upgraded to include gaseous ammonia port injection fuelling,with the aim of understanding maximum viable ammonia substitution ratios across the speedload operating map.The work was conducted at varied effective compression ratios under overall stoichiometric conditions,with the spark timing re-optimised for maximum brake torque at all stable logged sites.The experiments included industry standard measurements of combustion,performance,and engine-out emissions(including NH3“slip”).With a geometric compression ratio of 11.2:1,it was found possible to run the engine on pure ammonia at low engine speeds(1000-1800 rpm)and loads of 12 bar net IMEP.When progressively dropping down below this load limit an increasing amount of gasoline co-firing was required to avoid engine misfire.When operating at 1800 rpm and 12 bar net IMEP,all emissions of carbon(CO_(2),CO,unburned hydrocarbons)and NOx decreased considerably when switching to higher NH_(3) substitution ratios,with NOx reduced by~45%at 1800 rpm/12 bar when switching from pure gasoline to pure NH_(3)(associated with longer and cooler combustion).By further increasing the geometric compression ratio to 12.4 and reducing the intake camshaft duration for maximum effective compression ratio,it was possible to operate the engine on pure ammonia at much lower loads in a fully warmed up state(e.g.,linear low load limit line from 1000 rpm/6 bar net IMEP to 1800 rpm/9 bar net IMEP).Under all conditions,the indicated thermal efficiency of the engine was either equivalent to or slightly higher than that obtained using gasoline-only due to the favourable anti-knock rating of NH_(3).Ongoing work is concerned with detailed breakdown of individual NOx species together with measuring the impact of hydrogen enrichment across the operating map.展开更多
All components of a turbocharger compressor are axisymmetric except for the spiral-shaped,gas-collecting overhung volute.In this paper,a novel experimental method to evaluate the impact of the volute's asymmetry o...All components of a turbocharger compressor are axisymmetric except for the spiral-shaped,gas-collecting overhung volute.In this paper,a novel experimental method to evaluate the impact of the volute's asymmetry on centrifugal compressor performance is proposed and applied to a high pressure-ratio turbocharger compressor.This method can isolate the impact of the volute's asymmetry on the compressor performance for the first time.Experiments prove the considerable impact of the volute's asymmetry on the compressor performance,especially the stability and efficiency.The impact of the volute's asymmetry on compressor stability correlates with rotational speed and thus with the pressure ratio,constricting the stable flow range by up to 47 percent and decreasing the maximum efficiency by 4.8 percent at the design speed.The results provide evidence to exploit the potential of intrinsic non-axisymmetric flow induced by asymmetric volute to improve the performance of turbocharger compressor with a high pressure ratio.展开更多
基金Project(2011CB707201)supported by the National Basic Research Program of ChinaProject(51376057)supported by the National Natural Science Foundation of China
文摘To promote the fuel utilization efficiency of IC engine, an approach was proposed for IC engine coolant energy recovery based on low-temperature organic Rankine cycle(ORC). The ORC system uses IC engine coolant as heat source, and it is coupled to the IC engine cooling system. After various kinds of organic working media were compared, R124 was selected as the ORC working medium. According to IC engine operating conditions and coolant energy characteristics, the major parameters of ORC system were preliminary designed. Then, the effects of various parameters on cycle performance and recovery potential of coolant energy were analyzed via cycle process calculation. The results indicate that cycle efficiency is mainly influenced by the working pressure of ORC, while the maximum working pressure is limited by IC engine coolant temperature. At the same working pressure, cycle efficiency is hardly affected by both the mass flow rate and temperature of working medium. When the bottom cycle working pressure arrives at the maximum allowable value of 1.6 MPa, the fuel utilization efficiency of IC engine could be improved by 12.1%.All these demonstrate that this low-temperature ORC is a useful energy-saving technology for IC engine.
文摘Based on the theory of thermal radiation,a contact type optical fiber pyrometer applied in IC engine is put forward.It is composed of three parts:a blackbody probe,optical system,electrical process system.The key technology of design is discussed.Experiment is given to prove that the pyrometer has much higher responsive speed,distinguishability and much longer running life than other pyrometers.
文摘In this study, combustion of methane was simulated using four kinetic models of methane in CHEMKIN 4.1.1 for 0-D closed internal combustion （IC） engine reactor. Two detailed （GRIMECH3.0 ＆ UBC MECH2.0） and two reduced （One step ＆ Four steps） models were examined for various IC engine designs. The detailed models （GRIMECH3.0, ＆ UBC MECH2.0） and 4-step models successfully predicted the combustion while global model was unable to predict any combustion reaction. This study illustrated that the detailed model showed good concordances in the prediction of chamber pressure, temperature and major combustion species profiles. The detailed models also exhibited the capabilities to predict the pollutants formation in an IC engine while the reduced schemes showed failure in the prediction of pollutants emissions. Although, there are discrepancies among the profiles of four considered model, the detailed models （GRIMECH3.0 ＆ UBC MECH2.0） produced the acceptable agreement in the species prediction and formation of pollutants.
文摘With the intensifying competition in the integrated circuit(IC)industry,the high turnover rate of integrated circuit engineers has become a prominent issue affecting the technological continuity of high-precision,specialized,and innovative enterprises.As a representative of such enterprises,JL Technology has faced challenges to its R&D efficiency due to talent loss in recent years.This study takes this enterprise as a case to explore feasible paths to reduce turnover rates through optimizing training and career development systems.The research designs a method combining learning maps and talent maps,utilizes a competency model to clarify the direction for engineers’skill improvement,implements talent classification management using a nine-grid model,and achieves personalized training through Individual Development Plans(IDPs).Analysis of the enterprise’s historical data reveals that the main reasons for turnover are unclear career development paths and insufficient resources for skill improvement.After pilot implementation,the turnover rate in core departments decreased by 12%,and employee satisfaction with training increased by 24%.The results indicate that matching systematic talent reviews with dynamic learning resources can effectively enhance engineers’sense of belonging.This study provides a set of highly operational management tools for small and medium-sized high-precision,specialized,and innovative technology enterprises,verifies their applicability in such enterprises,and offers replicable experiences for similar enterprises to optimize their talent strategies[1].
文摘The health monitoring has been studied to ensure integrity of design of engine structure by detection,quantification,and prediction of damages.Early detection of faults may allow the downtime of maintenance to be rescheduled,thus preventing sudden shutdown of machines.In cylinder pressure developed,vibrations and noise emissions data provide a rich source of information about condition of engines.Monitoring of vibrations and noise emissions are novel non-intrusive methodologies for which positioning of various transducers are important issue.The presented work shows applicability of these diagnosis methodologies adopted in case of diesel engines.The effects of changing various fuel injection parameters was analyzed.Scope of using non-intrusive technique has been analyzed by changing locations of microphone.Novelty of this worklies in exploring signal processing methods for various locations around the engine test set up.Various frequency ranges of contributing noise and vibration sources were identified.Time-Frequency analysis showed the onset of various cyclic.Based on the identification of various frequency bands,it is possible to device suitable filters in order to extract more information.
基金Project (No. 2011BAE22B05) supported by the National Key Technologies Supporting Program of China during the 12th Five-Year Plan Period
文摘In this study,we report an analysis of cylinder head vibration signals at a steady engine speed using short-time Fourier transform(STFT).Three popular time-frequency analysis techniques,i.e.,STFT,analytic wavelet transform(AWT) and S transform(ST),have been examined.AWT and ST are often applied in engine signal analyses.In particular,an AWT expression in terms of the quality factor Q and an analytical relationship between ST and AWT have been derived.The time-frequency resolution of a Gaussian function windowed STFT was studied via numerical simulation.Based on the simulation,the empirical limits for the lowest distinguishable frequency as well as the time and frequency resolutions were determined.These can provide insights for window width selection,spectrogram interpretation and artifact identification.Gaussian function windowed STFTs were applied to some cylinder head vibration signals.The spectrograms of the same signals from ST and AWT were also determined for comparison.The results indicate that the uniform resolution feature of STFT is not necessarily a disadvantage for time-frequency analysis of vibration signals when the engine is in stationary state because it can more accurately localize the frequency components excited by transient excitations without much loss of time resolution.
文摘Turbochargers have been known in compression ignition engines for power generation.Recent trends in power generation through gas cycles have recorded successes via turbochargers application in spark ignition engines as well.When power cycles are turbocharged,there is a general expectation of a higher power and performance output from the cycle as compared to when they are naturally aspirated.This research was conducted to estimate the thermodynamic properties of a spark ignition engine power generating system when it is both naturally aspirated and when the same system is turbocharged to 2.5 times the amount of air in natural aspiration.Octane fuel was employed for petrol approximation during this study.The system process was broken down into stages of charging between natural aspiration and turbocharged;thus MATLAB program was applied to model the system for the case of natural aspiration and turbocharging with no increase in fuel supply.The results were used for both analyses and comparison which showed that the system generates slightly more power with turbocharging at 0%increase in fuel consumption.The natural aspiration achieved values are 2.8232 kJ/mol and 55.26%for output and efficiency respectively,while the turbocharged engine produced optimal values of 2.8833 kJ/mol and 56.51%for output and efficiency.The air fuel ratio by mole for the turbocharged engine was 145.18:1,which shows a greater fuel economy of 59%as compared to the 59.5:1 A/F(air/fuel)ratio of the naturally aspirated engine.
文摘This paper presents an application of adaptive neural network model-based predictive control (MPC) to the air-fuel ratio of an engine simulation. A multi-layer perceptron (MLP) neural network is trained using two on-line training algorithms: a back propagation algorithm and a recursive least squares (RLS) algorithm. It is used to model parameter uncertainties in the nonlinear dynamics of internal combustion (IC) engines. Based on the adaptive model, an MPC strategy for controlling air-fuel ratio is realized, and its control performance compared with that of a traditional PI controller. A reduced Hessian method, a newly developed sequential quadratic programming (SQP) method for solving nonlinear programming (NLP) problems, is implemented to speed up nonlinear optimization in the MPC. Keywords Air-fuel ratio control - IC engine - adaptive neural networks - nonlinear programming - model predictive control Shi-Wei Wang PhD student, Liverpool John Moores University; MSc in Control Systems, University of Sheffield, 2003; BEng in Automatic Technology, Jilin University, 2000; Current research interests automotive engine control, model predictive control, sliding mode control, neural networks.Ding-Li Yu obtained B.Eng from Harbin Civil Engineering College, Harbin, China in 1981, M.Sc from Jilin University of Technology, Changchun, China in 1986 and PhD from Coventry University, U.K. in 1995, all in control engineering. He is currently a Reader in Process Control at Liverpool John Moores University, U.K. His current research interests are in process control, engine control, fault detection and adaptive neural nets. He is a member of SAFEPROCESS TC in IFAC and an associate editor of the IJMIC and the IJISS.
基金supported by the National Natural Science Foundation of China(No.61833015)。
文摘Proprietary(or semi-proprietary)protocols are widely adopted in industrial control systems(ICSs).Inferring protocol format by reverse engineering is important for many network security applications,e.g.,program tests and intrusion detection.Conventional protocol reverse engineering methods have been proposed which are considered time-consuming,tedious,and error-prone.Recently,automatical protocol reverse engineering methods have been proposed which are,however,neither effective in handling binary-based ICS protocols based on network traffic analysis nor accurate in extracting protocol fields from protocol implementations.In this paper,we present a framework called the industrial control system protocol reverse engineering framework(ICSPRF)that aims to extract ICS protocol fields with high accuracy.ICSPRF is based on the key insight that an individual field in a message is typically handled in the same execution context,e.g.,basic block(BBL)group.As a result,by monitoring program execution,we can collect the tainted data information processed in every BBL group in the execution trace and cluster it to derive the protocol format.We evaluate our approach with six open-source ICS protocol implementations.The results show that ICSPRF can identify individual protocol fields with high accuracy(on average a 94.3%match ratio).ICSPRF also has a low coarse-grained and overly fine-grained match ratio.For the same metric,ICSPRF is more accurate than AutoFormat(88.5%for all evaluated protocols and 80.0%for binary-based protocols).
基金EPSRC-MariNH3-Grant number EP/W016656/1.Business,Energy&Industrial Strategy(BEIS).
文摘Ammonia(NH_(3))is emerging as a potential favoured fuel for longer range decarbonised heavy transport,particularly in the marine sector,predominantly due to highly favourable characteristics as an effective hydrogen carrier.This is despite generally unfavourable combustion and toxicity attributes,restricting end use to applications where robust health and safety protocols can always be upheld.In the currently reported work,a spark ignited thermodynamic single cylinder research engine equipped with gasoline direct injection was upgraded to include gaseous ammonia port injection fuelling,with the aim of understanding maximum viable ammonia substitution ratios across the speedload operating map.The work was conducted at varied effective compression ratios under overall stoichiometric conditions,with the spark timing re-optimised for maximum brake torque at all stable logged sites.The experiments included industry standard measurements of combustion,performance,and engine-out emissions(including NH3“slip”).With a geometric compression ratio of 11.2:1,it was found possible to run the engine on pure ammonia at low engine speeds(1000-1800 rpm)and loads of 12 bar net IMEP.When progressively dropping down below this load limit an increasing amount of gasoline co-firing was required to avoid engine misfire.When operating at 1800 rpm and 12 bar net IMEP,all emissions of carbon(CO_(2),CO,unburned hydrocarbons)and NOx decreased considerably when switching to higher NH_(3) substitution ratios,with NOx reduced by~45%at 1800 rpm/12 bar when switching from pure gasoline to pure NH_(3)(associated with longer and cooler combustion).By further increasing the geometric compression ratio to 12.4 and reducing the intake camshaft duration for maximum effective compression ratio,it was possible to operate the engine on pure ammonia at much lower loads in a fully warmed up state(e.g.,linear low load limit line from 1000 rpm/6 bar net IMEP to 1800 rpm/9 bar net IMEP).Under all conditions,the indicated thermal efficiency of the engine was either equivalent to or slightly higher than that obtained using gasoline-only due to the favourable anti-knock rating of NH_(3).Ongoing work is concerned with detailed breakdown of individual NOx species together with measuring the impact of hydrogen enrichment across the operating map.
基金supported by the National Natural Science Foundation of China (Grant No. 50806040)
文摘All components of a turbocharger compressor are axisymmetric except for the spiral-shaped,gas-collecting overhung volute.In this paper,a novel experimental method to evaluate the impact of the volute's asymmetry on centrifugal compressor performance is proposed and applied to a high pressure-ratio turbocharger compressor.This method can isolate the impact of the volute's asymmetry on the compressor performance for the first time.Experiments prove the considerable impact of the volute's asymmetry on the compressor performance,especially the stability and efficiency.The impact of the volute's asymmetry on compressor stability correlates with rotational speed and thus with the pressure ratio,constricting the stable flow range by up to 47 percent and decreasing the maximum efficiency by 4.8 percent at the design speed.The results provide evidence to exploit the potential of intrinsic non-axisymmetric flow induced by asymmetric volute to improve the performance of turbocharger compressor with a high pressure ratio.
