Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomogr...Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomographic Particle Image Velocimetry(Tomo-PIV)and planar Particle Image Velocimetry(PIV).Based on the analysis of the 3D time-averaged swirling flow structures and 3D Proper Orthogonal Decomposition(POD)of the Tomo-PIV data,typical coherent flow structures,including the Corner Recirculation Zone(CRZ),Central Recirculation Zone(CTRZ),and Lip Recirculation Zone(LRZ),were extracted.The counter-rotating dual-stage swirler with a Venturi flare generates the independence process of vortex breakdown from the main stage and pilot stage,leading to the formation of an LRZ and a smaller CTRZ near the nozzle outlet.The confinement squeezes the CRZ to the corner and causes a reverse rotation flow to limit the shape of the CTRZ.A large-scale flow structure caused by the main stage features an explosive breakup,flapping,and Precessing Vortex Core(PVC).The explosive breakup mode dominates the swirling flow structures owing to the expansion and construction of the main jet,whereas the flapping mode is related to the wake perturbation.Confinement limits the expansion of PVC and causes it to contract after the impacting area.展开更多
The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry （PIV）. Velocity compo...The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry （PIV）. Velocity compo- nents, fluctuation velocity, Reynolds stress and recirculation zone length are obtained, respectively. Influences of geometric parameter of primary hole, arrangement of primary hole, inlet air temperature, first-stage swirler an- gle and fuel/air ratio on flow field are investigated, respectively. The experimental results reveal that the primary recirculation zone lengths of combustion flow field are shorter than those of cold flow field, and the primary reeir- culation zone lengths decrease with the increase of inlet air temperature and fuel/air ratio. The change of the geo- metric parameter of primary hole casts an important influence on the swirler flow field in two-stage swirler com- bustor.展开更多
The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field.In the meantime,the number of unknown parameters increases with the number of c...The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field.In the meantime,the number of unknown parameters increases with the number of concentrically mounted swirlers.The available literature is nonetheless limited,and designers are obligated to increase the number of initial assumptions.In this article,three kinds of triple swirlers are employed and simulations are performed to determine the effect of each parameter on the swirler performance.Based on the correlation provided,overlengthening the radial vane length could result in significant changes in the flow field from the jetlike pattern to a wide swirl-jet angle due to the Coanda effect.Passage width should also have the potential to alter the swirl-jet angle and velocity field at the exit of the swirler.展开更多
A triple swirler combustor is considered to be a promising solution for future high temperature rise combustors. The present paper aims to study dilution holes including primary dilution holes and secondary dilution h...A triple swirler combustor is considered to be a promising solution for future high temperature rise combustors. The present paper aims to study dilution holes including primary dilution holes and secondary dilution holes on the performance of a triple swirler combustor. Experimental investigations are conducted at different inlet airflow velocities（40–70 m/s） and combustor overall fuel–air ratio with fixed inlet airflow temperature（473 K） and atmospheric pressure. The experimental results show that the ignition is very difficult with specific performance of high ignition fuel–air ratio when the primary dilution holes are located 0.6H（where H is the liner dome height）downstream the dome, while the other four cases have almost the same ignition performance. The position of primary dilution holes has an effect on lean blowout stability and has a large influence on combustion efficiency. The combustion efficiency is the highest when the primary dilution holes are placed 0.9H downstream the dome among the five different locations.For the secondary dilution holes, the pattern factor of Design A is better than that of Design B.展开更多
This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic ther...This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic thermoacoustic mode.The swirler as an origin of the swirling flow is also the source of the flow disturbance,which has effects on the flame response.The location of the swirler is varied in the experiment to study the effect on combustion instabilities and flame transfer functions.A low order model is built to analyze the thermoacoustic instabilities of the combustion system.The experimental results show that the ITA switches from an unstable state to a stable state as the swirl mixing distance changes with an increment of 15 mm;while the instability of the quarter-wave mode is not varied.The measured Flame Transfer Functions(FTFs)show that the gain curves of the frequency-dependent FTFs seem to be stretched or compressed with the modulation of the swirler position,which has effects on frequencies and instabilities of thermoacoustic modes.With the low order model,the effects of flame response on combustion instabilities are analyzed and the flame dominant nature of the ITA mode is confirmed.展开更多
The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the...The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the furnace coupled with the corrosive marine environment swirler material showed accelerated degradation and material wastage. An investigation into the feasibility of manufacturing the existing swirler with an alternate material or coating the swirler material with a thermal barrier coating was undertaken. Based on their properties and performance, SS 304 and SS 316 were proposed as the replacement materials for the swirler. The other alternative of coating the existing swirlers with a form thermal barrier coating to observe for any improvement in their performance at elevated temperatures was also tested. Stellite, which is a Ni-Co based coating, was carried out on the MS samples and the same were exposed to same temperatures mentioned above. The performance of the available options was evaluated with respect to the grain structure of the material, the hardness value of the materials and deterioration at elevated temperatures. Investigation showed the proposed materials/ coatings like SS 304, SS 316 and Stellite coating revealed that SS 316 is the material best suited for high temperature application.展开更多
Elbow wear is a major threat to the multiphase pipeline transportation industry,which has a negative impact on the stable operation of the transportation system.In order to find the wear reduction methods of elbows in...Elbow wear is a major threat to the multiphase pipeline transportation industry,which has a negative impact on the stable operation of the transportation system.In order to find the wear reduction methods of elbows in the fluidization pipeline transportation system for 2000-meter-deep coal resources,the swirler was installed upstream of the elbows,and wear simulations and tests of three kinds of elbows were carried out.The results showed that the maximum wear rate(MWR)of elbows increased and then decreased along the elbow angle.Due to the different directions of gravity,the heavy wear position(HWP)of the horizontal-vertical(H-V)elbow was in front of the vertical-horizontal(V-H)elbow.Because the downstream portion of the horizontal-horizontal(H-H)elbow was still a horizontal pipe,the HWP of the H-H elbow almost covered the whole elbow.The swirler placed upstream of the elbows could make the particles at the elbow move to the intrados of the elbows,resulting in less collision between the particles and the extrados of the elbows,thus reducing the wear of the elbows.The wear reduction effects of swirlers on three different elbows were favorably connected with the guide vane angle(GVA)and negatively correlated with the guide vane length(GVL),decreased first and then increased as the guide vane height(GVH)increased,and were little affected by the guide vane number(GVN)and the guide vane thickness(GVT).The mathematical models between the MWR of the elbows and guide vane parameters were established.By bench tests,the wear reduction effect of three kinds of elbows under the optimal guide vane parameters was 58.4%,76.9%,and 78.6%,respectively.The errors between the bench test results and the simulation results were around 10%.展开更多
Combustion with lean premixed and low swirl is an effective way of flame organization.It can improve the flame stability and reduce NOX emission.In this kind of combustion,one of the most important issues is fuel/air ...Combustion with lean premixed and low swirl is an effective way of flame organization.It can improve the flame stability and reduce NOX emission.In this kind of combustion,one of the most important issues is fuel/air premixed characteristics.How the structure parameters influence that issue is figured out through numerical simulation.The structure parameters concerned in the study are as follows.They are shape of blades,number of blades,location and shape of gas jet.The influences of them are analysed with comprehensive consideration of many aspects.With the same light shading rate and stagger angle,the axial swirler with curved blades has worse premixed uniformity and lower pressure loss than the one with straight blades.With the same structure of each blade,the decrease of the quantity of blades does influence the pressure loss,while the quantity of gas jets changes correspondingly.But it has little effect on premixed uniformity in a certain range.However,more blades make contribution to better premixed performance.When the total flow area is the same,the axial and circumferential positions of the fuel jets also greatly influence the premixing process.When the fuel jets are upstream the blades and locate at middle of the vanes,the premixing performance is the best.Meanwhile,the jet direction of the fuel jets is a very important influencing factor of the premixing process.When the fuel jet direction is oblique downward at an angle of 30°to the horizontal,the premixing effect is better than the horizontal outflow,which is better than the oblique upward structure.展开更多
In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple ...In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple electrodes with staggered arrangement on both sides of combustor＇s expansion section. The plasma swirler can enhance combustion stability through ionizing the air to produce active free radical and promoting the swirling air. In the experiments, the flame response to the plasma swider was examined with OH distribution by planar laser induced fluorescence （PLIF）. The experimental results showed that the flame reaction zone was broadened with the increase of the plasma exciting, and this demonstrated that the plasma swirler could be used to control diffusion flame. The design of plasma swirler is feasible.展开更多
基金supported by the National Natural Science Foundation of China(Nos.12232002,12072017,12002199,and 11721202)。
文摘Three-Dimensional(3D)swirling flow structures,generated by a counter-rotating dualstage swirler in a confined chamber with a confinement ratio of 1.53,were experimentally investigated at Re=2.3×10^(5)using Tomographic Particle Image Velocimetry(Tomo-PIV)and planar Particle Image Velocimetry(PIV).Based on the analysis of the 3D time-averaged swirling flow structures and 3D Proper Orthogonal Decomposition(POD)of the Tomo-PIV data,typical coherent flow structures,including the Corner Recirculation Zone(CRZ),Central Recirculation Zone(CTRZ),and Lip Recirculation Zone(LRZ),were extracted.The counter-rotating dual-stage swirler with a Venturi flare generates the independence process of vortex breakdown from the main stage and pilot stage,leading to the formation of an LRZ and a smaller CTRZ near the nozzle outlet.The confinement squeezes the CRZ to the corner and causes a reverse rotation flow to limit the shape of the CTRZ.A large-scale flow structure caused by the main stage features an explosive breakup,flapping,and Precessing Vortex Core(PVC).The explosive breakup mode dominates the swirling flow structures owing to the expansion and construction of the main jet,whereas the flapping mode is related to the wake perturbation.Confinement limits the expansion of PVC and causes it to contract after the impacting area.
基金Supported by the National Natural Science Foundation of China(50906040)the Nanjing University of Aeronautics and Astronautics Research Funding(NZ2012107,NS2010052)~~
文摘The characteristics of swirler flow field, including cold flow field and combustion flow field, in gas tur- bine combustor with two-stage swirler are studied by using particle image velocimetry （PIV）. Velocity compo- nents, fluctuation velocity, Reynolds stress and recirculation zone length are obtained, respectively. Influences of geometric parameter of primary hole, arrangement of primary hole, inlet air temperature, first-stage swirler an- gle and fuel/air ratio on flow field are investigated, respectively. The experimental results reveal that the primary recirculation zone lengths of combustion flow field are shorter than those of cold flow field, and the primary reeir- culation zone lengths decrease with the increase of inlet air temperature and fuel/air ratio. The change of the geo- metric parameter of primary hole casts an important influence on the swirler flow field in two-stage swirler com- bustor.
基金supported by Korea Electric Power Corporation through Korea Electrical Engineering and Science Research Institute(Grant 18B-022)
文摘The design of axial or radial swirlers typically governs a number of geometrical parameters that are determined by the desired flow field.In the meantime,the number of unknown parameters increases with the number of concentrically mounted swirlers.The available literature is nonetheless limited,and designers are obligated to increase the number of initial assumptions.In this article,three kinds of triple swirlers are employed and simulations are performed to determine the effect of each parameter on the swirler performance.Based on the correlation provided,overlengthening the radial vane length could result in significant changes in the flow field from the jetlike pattern to a wide swirl-jet angle due to the Coanda effect.Passage width should also have the potential to alter the swirl-jet angle and velocity field at the exit of the swirler.
基金supported by Funding for Outstanding Doctoral Dissertation in NUAA (No. BCXJ 14-01)Funding of Jiangsu Innovation Program for Graduate Education (No. CXLX12_0169)
文摘A triple swirler combustor is considered to be a promising solution for future high temperature rise combustors. The present paper aims to study dilution holes including primary dilution holes and secondary dilution holes on the performance of a triple swirler combustor. Experimental investigations are conducted at different inlet airflow velocities（40–70 m/s） and combustor overall fuel–air ratio with fixed inlet airflow temperature（473 K） and atmospheric pressure. The experimental results show that the ignition is very difficult with specific performance of high ignition fuel–air ratio when the primary dilution holes are located 0.6H（where H is the liner dome height）downstream the dome, while the other four cases have almost the same ignition performance. The position of primary dilution holes has an effect on lean blowout stability and has a large influence on combustion efficiency. The combustion efficiency is the highest when the primary dilution holes are placed 0.9H downstream the dome among the five different locations.For the secondary dilution holes, the pattern factor of Design A is better than that of Design B.
基金supported the National Natural Science Foundation of China(Nos.51676126 and 51776191)。
文摘This study is concerned with the experimental and theoretical investigation of the combustion instabilities in a premixed swirl combustor.It is focused on the effects of the swirl mixing distance on the intrinsic thermoacoustic mode.The swirler as an origin of the swirling flow is also the source of the flow disturbance,which has effects on the flame response.The location of the swirler is varied in the experiment to study the effect on combustion instabilities and flame transfer functions.A low order model is built to analyze the thermoacoustic instabilities of the combustion system.The experimental results show that the ITA switches from an unstable state to a stable state as the swirl mixing distance changes with an increment of 15 mm;while the instability of the quarter-wave mode is not varied.The measured Flame Transfer Functions(FTFs)show that the gain curves of the frequency-dependent FTFs seem to be stretched or compressed with the modulation of the swirler position,which has effects on frequencies and instabilities of thermoacoustic modes.With the low order model,the effects of flame response on combustion instabilities are analyzed and the flame dominant nature of the ITA mode is confirmed.
文摘The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the furnace coupled with the corrosive marine environment swirler material showed accelerated degradation and material wastage. An investigation into the feasibility of manufacturing the existing swirler with an alternate material or coating the swirler material with a thermal barrier coating was undertaken. Based on their properties and performance, SS 304 and SS 316 were proposed as the replacement materials for the swirler. The other alternative of coating the existing swirlers with a form thermal barrier coating to observe for any improvement in their performance at elevated temperatures was also tested. Stellite, which is a Ni-Co based coating, was carried out on the MS samples and the same were exposed to same temperatures mentioned above. The performance of the available options was evaluated with respect to the grain structure of the material, the hardness value of the materials and deterioration at elevated temperatures. Investigation showed the proposed materials/ coatings like SS 304, SS 316 and Stellite coating revealed that SS 316 is the material best suited for high temperature application.
基金the“Double-First Class”Discipline Construction Project of China University of Mining and Technology(Grant No.2019XKPT03)the Graduate Innovation Program of China University of Mining and Technology(Grant No.2022WLKXJ013)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Elbow wear is a major threat to the multiphase pipeline transportation industry,which has a negative impact on the stable operation of the transportation system.In order to find the wear reduction methods of elbows in the fluidization pipeline transportation system for 2000-meter-deep coal resources,the swirler was installed upstream of the elbows,and wear simulations and tests of three kinds of elbows were carried out.The results showed that the maximum wear rate(MWR)of elbows increased and then decreased along the elbow angle.Due to the different directions of gravity,the heavy wear position(HWP)of the horizontal-vertical(H-V)elbow was in front of the vertical-horizontal(V-H)elbow.Because the downstream portion of the horizontal-horizontal(H-H)elbow was still a horizontal pipe,the HWP of the H-H elbow almost covered the whole elbow.The swirler placed upstream of the elbows could make the particles at the elbow move to the intrados of the elbows,resulting in less collision between the particles and the extrados of the elbows,thus reducing the wear of the elbows.The wear reduction effects of swirlers on three different elbows were favorably connected with the guide vane angle(GVA)and negatively correlated with the guide vane length(GVL),decreased first and then increased as the guide vane height(GVH)increased,and were little affected by the guide vane number(GVN)and the guide vane thickness(GVT).The mathematical models between the MWR of the elbows and guide vane parameters were established.By bench tests,the wear reduction effect of three kinds of elbows under the optimal guide vane parameters was 58.4%,76.9%,and 78.6%,respectively.The errors between the bench test results and the simulation results were around 10%.
基金This study is supported by Shanghai Committee of Science and Technology(Grant No.18DZ1202003).
文摘Combustion with lean premixed and low swirl is an effective way of flame organization.It can improve the flame stability and reduce NOX emission.In this kind of combustion,one of the most important issues is fuel/air premixed characteristics.How the structure parameters influence that issue is figured out through numerical simulation.The structure parameters concerned in the study are as follows.They are shape of blades,number of blades,location and shape of gas jet.The influences of them are analysed with comprehensive consideration of many aspects.With the same light shading rate and stagger angle,the axial swirler with curved blades has worse premixed uniformity and lower pressure loss than the one with straight blades.With the same structure of each blade,the decrease of the quantity of blades does influence the pressure loss,while the quantity of gas jets changes correspondingly.But it has little effect on premixed uniformity in a certain range.However,more blades make contribution to better premixed performance.When the total flow area is the same,the axial and circumferential positions of the fuel jets also greatly influence the premixing process.When the fuel jets are upstream the blades and locate at middle of the vanes,the premixing performance is the best.Meanwhile,the jet direction of the fuel jets is a very important influencing factor of the premixing process.When the fuel jet direction is oblique downward at an angle of 30°to the horizontal,the premixing effect is better than the horizontal outflow,which is better than the oblique upward structure.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51006104, 51076150 and 50906085)
文摘In this paper, the design of plasma swirler is presented in detail. The experiments were carded out to verify the feasibility of using plasma swirler to control diffusion flame. The plasma swider consists of multiple electrodes with staggered arrangement on both sides of combustor＇s expansion section. The plasma swirler can enhance combustion stability through ionizing the air to produce active free radical and promoting the swirling air. In the experiments, the flame response to the plasma swider was examined with OH distribution by planar laser induced fluorescence （PLIF）. The experimental results showed that the flame reaction zone was broadened with the increase of the plasma exciting, and this demonstrated that the plasma swirler could be used to control diffusion flame. The design of plasma swirler is feasible.
