Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportio...Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor. Due to the presence of entrainment phenomenon, the total air flow in the cavity zone is difficult to estimate. To overcome the measurement difficulty, this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity. In accordance with the measurement principle, a TVC model fueled by methane is designed. Under two experimental conditions, i.e. with and without direct air intake in the cavity, the influence of the mainstream air flow velocity, the air intake velocity in the cavity, the height of inlet channel, the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied, respectively, through experiment at atmospheric temperature and pressure. The results suggest that the air flow velocity of mainstream, the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment, while the influence of structural proportion of the cavity is comparatively insignificant. The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.展开更多
A trapped vortex combustor （TVC） has been a very promising novel concept for it offers improvements in lean blow out, altitude relight, operating range, as well as a potential to decrease NOx emissions compared to c...A trapped vortex combustor （TVC） has been a very promising novel concept for it offers improvements in lean blow out, altitude relight, operating range, as well as a potential to decrease NOx emissions compared to conventional combustors. The present paper discusses the improved designs of the new combustor over the prior ones of our research group, including that：a） the over-all dimensions, both axial and radial, are reduced to those of an actual aero-engine combustor; b） the air flow distribution is optimized, and especially 15% of the air is fed into the liner as cooling air; c） a straight-wall diffuser with divergence angle 9°is added. A series of experiments （cavity-fueled only, under atmospheric pressure） has been conducted to investigate the performance of the improved TVC. Experimental results show that at the inlet temperature of 523 K, the inlet pressure of 0.1 MPa, stable operation of the TVC test rig is observed for the Mach number 0.15-0.34, indicating good flame stability; the combustion efficiency obtained in this paper falls into the range of 60%-96%; as the total excess air ratio increases, the combustion efficiency decreases, while the increase of the inlet temperature is beneficial to high combustion efficiency; besides, the optimal Mach numbers for high combustion efficiency under different inlet conditions are confirmed. The outlet temperature profiles feature a bottom in the midheight of the exit. This paper demonstrates the feasibility for the TVC to be applied to a realistic aero-engine preliminarily and provides reference for TVC design.展开更多
This paper presents results on the combustion of syngas fuel in re-circulating vortex combustor. The combustion stability is achieved through the use of cavities in which recirculation zones of hot products generated ...This paper presents results on the combustion of syngas fuel in re-circulating vortex combustor. The combustion stability is achieved through the use of cavities in which recirculation zones of hot products generated by the direct injection of fuel and air are created and acting as a continuous source of ignition for the incoming main fuel-air stream. CFD （computational fluid dynamics） analysis was performed in this study to test the combustion performance and emissions from the vortex trapped combustor using synthetic gas or syngas fuel produced from the gasification process. The flame temperature, the flow field and species concentrations inside the vortex trapped combustor were obtained. Several syngas fuels with different fuel compositions （H2, CO, CH4, CO2, N2 and H20） and lower heating values were tested in this study. The changes on the flame temperature and species concentrations inside the combustor, the emissions of NOx, CO, CO2 at the exit of the combustor, the combustor efficiency and the total pressure drop for syngas fuels are presented in this paper. The effect of H2/CO ratio and the mass fraction of each constituent of syngas fuels and hydrogen-methane fuel mixtures on the combustion and emissions performances were investigated.展开更多
The experimental research on cavity flow field plays an important part in the structural design and optimization study of trapped vortex combustor (TVC). Many of the previous flow field experiments were conducted in t...The experimental research on cavity flow field plays an important part in the structural design and optimization study of trapped vortex combustor (TVC). Many of the previous flow field experiments were conducted in the cold condition instead of during combustion. This paper adopting PIV system and Lambda-2 vortex criterion in-vestigates the influence of various factors, such as equivalent ratio in the cavity, air intake parameter in the cavity, mainstream air intake parameter and mainstream holder structure, on cavity flow field for a TVC using methane as the fuel. The experimental research showed that cold-condition flow field differed from the combustion flow field, in terms of either vortex core position or vortex structure. Mainstream air intake velocity and cavity air intake velocity affected the flow field structure. U-type and V-type mainstream holders had significant influence on cavity flow field.展开更多
Combustion performances of pure hydrogen in an experimental trapped vortex combustor have been tested underdifferent operating conditions. Pressure fluctuations, NOx emissions, OH distributions, and LBO (Lean Blow Out...Combustion performances of pure hydrogen in an experimental trapped vortex combustor have been tested underdifferent operating conditions. Pressure fluctuations, NOx emissions, OH distributions, and LBO (Lean Blow Out)were measured in the tests. Results indicate that the TVC test rig has successfully realized a double vortex constructionin the cavity zone in a wide range of flow conditions. Hydrogen combustion in the test rig has achievedan excellent LBO performance and relatively low NOx emissions. Through comparison of dynamic pressure data,OH fluctuation images, and NOx emissions, the optimal operating condition has been found out to be Φp=0.4,fuel split=0.4, and primary air/fuel premixed.展开更多
The cold flow characteristics are investigated to show the effect of the structural parameters of the flow guide vane on the trapped vortex combustor（TVC）. The results show that the structural parameters have signif...The cold flow characteristics are investigated to show the effect of the structural parameters of the flow guide vane on the trapped vortex combustor（TVC）. The results show that the structural parameters have significant effects on the TVC. As a/ H increases, the total pressure loss, the wall shear stress at the bottom of the cavity and the turbulent intensity in the main combustion zone increase. b/ B does not have a significant effect on the cavity flow structure and the total pressure loss, and the wall shear stress at the bottom of the cavity increases as b/ B increases. There is no significant increase of the turbulent intensity with the increase of b/ B. The increase of c/ L has little effect on the total pressure loss, and it is not conducive to a stable combustion. As c/ L increases, the wall shear stress at the bottom of the cavity decreases. When a/ H= 0.4, b/ B= 0.4, c/ L= 0.1, a desirable dual-vortex structure is formed with an acceptable pressure loss to achieve a stable combustion. Moreover, to ascertain that the flame is stable for different values of Vm a with the optimal structural parameters, the effect of Vm a on the flow field is discussed. Results suggest that the dual-vortex structure has no relationship with the increase of Vm a. Furthermore, an unsteady simulation is conducted to show the generation and the development of the dual-vortex.展开更多
The combustion and emission formation process of liquid fuel in the trapped vortex combustor(TVC)are very complicated.A trapped vortex combustor with replaceable bluff-bodies was designed to investigate these processe...The combustion and emission formation process of liquid fuel in the trapped vortex combustor(TVC)are very complicated.A trapped vortex combustor with replaceable bluff-bodies was designed to investigate these processes.The bluff-body widths varied from 0.021 m to 0.036 m.Experimental tests were carried out.Liquid RP-3 aviation kerosene was used in the tests.Emissions were measured under atmospheric pressure.The combustion process was analyzed theoretically in the viewpoints of relative evaporation time,mixing time and reaction time.Numerical simulations were also conducted to help analyze the formation and depletion processes of pollutants in TVC.The results reveal that atomization was a critical factor for formation and depletion processes of pollutants.By controlling mixing speed of burned and unburned gases and thus fuel-air uniformity,turbulence intensity could also affect emission levels.In addition,residence time also affected the emissions by affecting combustion completeness and the time for NOx formation.All these factors were combined in a complicated way to affect combustion process and pollutant emissions.展开更多
To improve the combustor performance of multi-point injection combustion,lobe nozzle design was applied to the aero-engine model combustor,by presetting the swirl through a certain twisted angle of the edge of the lob...To improve the combustor performance of multi-point injection combustion,lobe nozzle design was applied to the aero-engine model combustor,by presetting the swirl through a certain twisted angle of the edge of the lobe outlet.Numerical simulation in combination with modelling test is used in this paper.The effects of swirl vorticity presetting onto the vortex structure,the characteristics of combustion temperature field,the combustor exit temperature field quality,the combustion efficiency,and the NOx emissions of multi-point injection combustion chamber are investigated.Compared with the conventional vortex flow at the lobe outlet edge,the results of numerical simulation and water modelling test of the swirl vorticity presetting show that the swirl presetting can efficiently enhance the range and intensity of the lobe-induced vorticities.Besides,it can improve the uniformity of the combustion temperature in the combustor chamber,together with the reduced emissions of the pollutant NOx.Moreover,compared with the conventional lobe nozzle chamber,the swirl vortex presetting can effectively improve its combustion performance.The flow simulation test results demonstrate the fluid vortex structure in the combustion chamber and validate the simulation results.展开更多
文摘Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor. Due to the presence of entrainment phenomenon, the total air flow in the cavity zone is difficult to estimate. To overcome the measurement difficulty, this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity. In accordance with the measurement principle, a TVC model fueled by methane is designed. Under two experimental conditions, i.e. with and without direct air intake in the cavity, the influence of the mainstream air flow velocity, the air intake velocity in the cavity, the height of inlet channel, the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied, respectively, through experiment at atmospheric temperature and pressure. The results suggest that the air flow velocity of mainstream, the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment, while the influence of structural proportion of the cavity is comparatively insignificant. The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.
基金Aeronautical Science Foundation of China (2008ZB52013)Funding of Jiangsu Innovation Program for Graduate Education (CXLX11_0211)
文摘A trapped vortex combustor （TVC） has been a very promising novel concept for it offers improvements in lean blow out, altitude relight, operating range, as well as a potential to decrease NOx emissions compared to conventional combustors. The present paper discusses the improved designs of the new combustor over the prior ones of our research group, including that：a） the over-all dimensions, both axial and radial, are reduced to those of an actual aero-engine combustor; b） the air flow distribution is optimized, and especially 15% of the air is fed into the liner as cooling air; c） a straight-wall diffuser with divergence angle 9°is added. A series of experiments （cavity-fueled only, under atmospheric pressure） has been conducted to investigate the performance of the improved TVC. Experimental results show that at the inlet temperature of 523 K, the inlet pressure of 0.1 MPa, stable operation of the TVC test rig is observed for the Mach number 0.15-0.34, indicating good flame stability; the combustion efficiency obtained in this paper falls into the range of 60%-96%; as the total excess air ratio increases, the combustion efficiency decreases, while the increase of the inlet temperature is beneficial to high combustion efficiency; besides, the optimal Mach numbers for high combustion efficiency under different inlet conditions are confirmed. The outlet temperature profiles feature a bottom in the midheight of the exit. This paper demonstrates the feasibility for the TVC to be applied to a realistic aero-engine preliminarily and provides reference for TVC design.
文摘This paper presents results on the combustion of syngas fuel in re-circulating vortex combustor. The combustion stability is achieved through the use of cavities in which recirculation zones of hot products generated by the direct injection of fuel and air are created and acting as a continuous source of ignition for the incoming main fuel-air stream. CFD （computational fluid dynamics） analysis was performed in this study to test the combustion performance and emissions from the vortex trapped combustor using synthetic gas or syngas fuel produced from the gasification process. The flame temperature, the flow field and species concentrations inside the vortex trapped combustor were obtained. Several syngas fuels with different fuel compositions （H2, CO, CH4, CO2, N2 and H20） and lower heating values were tested in this study. The changes on the flame temperature and species concentrations inside the combustor, the emissions of NOx, CO, CO2 at the exit of the combustor, the combustor efficiency and the total pressure drop for syngas fuels are presented in this paper. The effect of H2/CO ratio and the mass fraction of each constituent of syngas fuels and hydrogen-methane fuel mixtures on the combustion and emissions performances were investigated.
文摘The experimental research on cavity flow field plays an important part in the structural design and optimization study of trapped vortex combustor (TVC). Many of the previous flow field experiments were conducted in the cold condition instead of during combustion. This paper adopting PIV system and Lambda-2 vortex criterion in-vestigates the influence of various factors, such as equivalent ratio in the cavity, air intake parameter in the cavity, mainstream air intake parameter and mainstream holder structure, on cavity flow field for a TVC using methane as the fuel. The experimental research showed that cold-condition flow field differed from the combustion flow field, in terms of either vortex core position or vortex structure. Mainstream air intake velocity and cavity air intake velocity affected the flow field structure. U-type and V-type mainstream holders had significant influence on cavity flow field.
基金National Natural Science Foundation of China (No. 50576098)the National High Technology R&D Project of China (No.2006AA05A104)
文摘Combustion performances of pure hydrogen in an experimental trapped vortex combustor have been tested underdifferent operating conditions. Pressure fluctuations, NOx emissions, OH distributions, and LBO (Lean Blow Out)were measured in the tests. Results indicate that the TVC test rig has successfully realized a double vortex constructionin the cavity zone in a wide range of flow conditions. Hydrogen combustion in the test rig has achievedan excellent LBO performance and relatively low NOx emissions. Through comparison of dynamic pressure data,OH fluctuation images, and NOx emissions, the optimal operating condition has been found out to be Φp=0.4,fuel split=0.4, and primary air/fuel premixed.
基金Project supported by the National Natural Science Foun-dation of China(Grant Nos.51066006,51266013)the Aero-nautical Science Fund(Grant Nos.2013ZB56002,2013ZB56004)
文摘The cold flow characteristics are investigated to show the effect of the structural parameters of the flow guide vane on the trapped vortex combustor（TVC）. The results show that the structural parameters have significant effects on the TVC. As a/ H increases, the total pressure loss, the wall shear stress at the bottom of the cavity and the turbulent intensity in the main combustion zone increase. b/ B does not have a significant effect on the cavity flow structure and the total pressure loss, and the wall shear stress at the bottom of the cavity increases as b/ B increases. There is no significant increase of the turbulent intensity with the increase of b/ B. The increase of c/ L has little effect on the total pressure loss, and it is not conducive to a stable combustion. As c/ L increases, the wall shear stress at the bottom of the cavity decreases. When a/ H= 0.4, b/ B= 0.4, c/ L= 0.1, a desirable dual-vortex structure is formed with an acceptable pressure loss to achieve a stable combustion. Moreover, to ascertain that the flame is stable for different values of Vm a with the optimal structural parameters, the effect of Vm a on the flow field is discussed. Results suggest that the dual-vortex structure has no relationship with the increase of Vm a. Furthermore, an unsteady simulation is conducted to show the generation and the development of the dual-vortex.
基金supported by the Fundamental Research Funds for the Central Universities (No. 106112017CDJXY320001)the open funds of Jiangsu Province Key Laboratory of Aerospace Power System (No. CEPE2018009)
文摘The combustion and emission formation process of liquid fuel in the trapped vortex combustor(TVC)are very complicated.A trapped vortex combustor with replaceable bluff-bodies was designed to investigate these processes.The bluff-body widths varied from 0.021 m to 0.036 m.Experimental tests were carried out.Liquid RP-3 aviation kerosene was used in the tests.Emissions were measured under atmospheric pressure.The combustion process was analyzed theoretically in the viewpoints of relative evaporation time,mixing time and reaction time.Numerical simulations were also conducted to help analyze the formation and depletion processes of pollutants in TVC.The results reveal that atomization was a critical factor for formation and depletion processes of pollutants.By controlling mixing speed of burned and unburned gases and thus fuel-air uniformity,turbulence intensity could also affect emission levels.In addition,residence time also affected the emissions by affecting combustion completeness and the time for NOx formation.All these factors were combined in a complicated way to affect combustion process and pollutant emissions.
基金supported by the Natural Science Fund of Liaoning Province Project (No. 201602566)
文摘To improve the combustor performance of multi-point injection combustion,lobe nozzle design was applied to the aero-engine model combustor,by presetting the swirl through a certain twisted angle of the edge of the lobe outlet.Numerical simulation in combination with modelling test is used in this paper.The effects of swirl vorticity presetting onto the vortex structure,the characteristics of combustion temperature field,the combustor exit temperature field quality,the combustion efficiency,and the NOx emissions of multi-point injection combustion chamber are investigated.Compared with the conventional vortex flow at the lobe outlet edge,the results of numerical simulation and water modelling test of the swirl vorticity presetting show that the swirl presetting can efficiently enhance the range and intensity of the lobe-induced vorticities.Besides,it can improve the uniformity of the combustion temperature in the combustor chamber,together with the reduced emissions of the pollutant NOx.Moreover,compared with the conventional lobe nozzle chamber,the swirl vortex presetting can effectively improve its combustion performance.The flow simulation test results demonstrate the fluid vortex structure in the combustion chamber and validate the simulation results.
