An effect of the swirling flow on the combustion performance is studied by the computational fluid dynamics(CFD) in a micro-gas turbine with a centrifugal compressor, dump diffuser and forward-flow combustor. The dist...An effect of the swirling flow on the combustion performance is studied by the computational fluid dynamics(CFD) in a micro-gas turbine with a centrifugal compressor, dump diffuser and forward-flow combustor. The distributions of air mass and the Temperature Pattern Factor(as: Overall Temperature Distribution Factor-OTDF) in outlet are investigated with two different swirling angles of compressed air as 0° and 15° in three combustors. The results show that the influences of swirling flow on the air distribution and OTDF cannot be neglected. Compared with no-swirling flow, the air through outer liner is more, and the air through the inner liner is less, and the pressure loss is bigger under the swirling condition in the same combustor. The Temperature Pattern Factor changes under the different swirling conditions.展开更多
Effect of venturi angle and main stage swirl intensity on flow field and interactions were investigated using PIV.The results showed the difference between the side sector and the middle sector was caused by interacti...Effect of venturi angle and main stage swirl intensity on flow field and interactions were investigated using PIV.The results showed the difference between the side sector and the middle sector was caused by interactions.The interactions were stronger with the rise of the main stage swirl intensity.When the swirl intensity was 0.7 and 0.9,there was little difference of the width of the recirculation zone.But the flow field had a great difference when the swirl intensity was 0.5 and 0.7,which means that when the swirl intensity was small,the swirl intensity had a great influence on the flow field.Venturi angle had a great influence on the flow field structure and interactions when the venturi angle was big,such as 90°.The venturi angle just had a small influence on the width of the recirculation zone when the venturi angle was relatively small,such as 28°and 52°.The velocity of the center plane between two sectors(plane 3)was small.There was a recirculation zone at upstream of the center plane between two sectors(plane 3)when the swirl intensity was 0.7 and 0.9,whereas not one when the swirl intensity was 0.5.The above was induced by interactions.In addition,the velocity of plane 1,plane 3,and plane 5 when the venturi angle was 52°was smaller than that of 28°and 90°.展开更多
The low NOx emission technology has become an important feature of advanced aviation engine.A wide range of applications attempt to take advantage of the fact that staged combustion under lean-premixed-prevaporized(LP...The low NOx emission technology has become an important feature of advanced aviation engine.A wide range of applications attempt to take advantage of the fact that staged combustion under lean-premixed-prevaporized(LPP)conditions can significantly cut down emission and improve combustion efficiency.This paper proposes a scheme with fuel centrally staged and multi-point injection.The mixing of fuel and air is improved,and the flame temperature is relative low in combustion zone,minimizing the formation of nitrogen oxides(NOx),especially thermal NOx.In terms of the field distribution of equivalence ratio and temperature obtained from Computational Fluid Dynamics(CFD),a chemical reactor network(CRN),including several different ideal reactor,namely perfectly stirred reactor(PSR)and plug flow reactor(PFR),is constructed to simulate the combustion process and predict pollution emission.The influences of the pilot equivalence ratio and percentage of pilot/main fuel on NOx and carbon monoxide(CO)emission were investigated by CRN model.The effects of the pilot fuel and primary fuel on pollution emission were investigated experimentally.Finally,the effects of pilot equivalence ratio and pilot fuel proportion on NOx emission were discussed in detail by comparing predict of CRN and experimental results.展开更多
Improvement on extinction and pollution emission have become one of the most prominent research topics in gas turbine.It is widely recognized that the fuel/air mixture distribution in the recirculation zone is a criti...Improvement on extinction and pollution emission have become one of the most prominent research topics in gas turbine.It is widely recognized that the fuel/air mixture distribution in the recirculation zone is a critical factor in improving lean blow-out(LBO) and ignition.This paper proposed a new low emission scheme with fuel staged centrally and hybrid injector to improve flameout and emission.A relative small amount of fuel enters into central pilot airblast atomizer burner and then atomized by inner swirl air.The remaining majority of fuel is directly injected into vane channels of the primary swirler through a series of holes located on the sidewall of the main stage.Only pilot stage is fueled under ignition and lean flameout condition.The uniformity of fuel/air mixture distribution in the primary zone of the new design decreases NOX emission,meanwhile the fuel air mixture in pilot recirculation zone is locally rich to improve flameout and ignition.Experimental investigation was conducted to compare the new scheme with baseline design of dual-swirler in terms of LBO and ignition characteristics under the same condition in a multi-sector combustor.It is found that the fuel-air ratio of ignition limit and LBO decrease with the reference velocity increasing.The experimental results also show that the new scheme successfully improve lean blow-out and broaden the operation range of the combustor.The experimental results indicated that the centrally staged scheme can widen the operation boundary of the combustor and can provide guidance for design and optimization of combustion chamber.展开更多
In this paper,the flow field characteristics of a double-swirl low-emission combustor were analyzed by using Particle Imaging Velocimetry(PIV)technology in an optical three-sector combustor test rig.The interactions b...In this paper,the flow field characteristics of a double-swirl low-emission combustor were analyzed by using Particle Imaging Velocimetry(PIV)technology in an optical three-sector combustor test rig.The interactions between sectors and the flow field structure were explained.The results illustrated that there was a big difference between the flow field structures of the middle sector and the side sector under the same pressure drop,which was mainly induced by the interactions between sectors.The interactions made the swirl intensity of the middle sector weaker than that of the side sector,which made the recirculation zone of the middle sector be smaller than that of the side sector.With the increase of swirler pressure drop,the jet velocity at the exit of the swirler,the jet expansion angle,the width of the recirculation zone and the recirculating speed of the central axis became larger,enhancing the interactions between air streams from middle sector and side sector.The flow velocity in the central plane between sectors was small,especially the radial velocity,mainly because of the loss of the swirl intensity by the interactions between flow field of adjacent sectors.The expansion angle determined the position of the vortex in the primary recirculation zone;the axial and radial position of the vortex move downstream and radial outward with the increase of the jet expansion angle.The results of the mechanism of flow field organization in this study can be used to support the design of new low-emission combustor.展开更多
The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, wh...The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real engine.In this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test section.The experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.展开更多
基金supported by National Natural Science Foundation of China with project No.51406202
文摘An effect of the swirling flow on the combustion performance is studied by the computational fluid dynamics(CFD) in a micro-gas turbine with a centrifugal compressor, dump diffuser and forward-flow combustor. The distributions of air mass and the Temperature Pattern Factor(as: Overall Temperature Distribution Factor-OTDF) in outlet are investigated with two different swirling angles of compressed air as 0° and 15° in three combustors. The results show that the influences of swirling flow on the air distribution and OTDF cannot be neglected. Compared with no-swirling flow, the air through outer liner is more, and the air through the inner liner is less, and the pressure loss is bigger under the swirling condition in the same combustor. The Temperature Pattern Factor changes under the different swirling conditions.
基金supported by National Natural Science Foundation of China(Grant No.51306182 and 61827802)。
文摘Effect of venturi angle and main stage swirl intensity on flow field and interactions were investigated using PIV.The results showed the difference between the side sector and the middle sector was caused by interactions.The interactions were stronger with the rise of the main stage swirl intensity.When the swirl intensity was 0.7 and 0.9,there was little difference of the width of the recirculation zone.But the flow field had a great difference when the swirl intensity was 0.5 and 0.7,which means that when the swirl intensity was small,the swirl intensity had a great influence on the flow field.Venturi angle had a great influence on the flow field structure and interactions when the venturi angle was big,such as 90°.The venturi angle just had a small influence on the width of the recirculation zone when the venturi angle was relatively small,such as 28°and 52°.The velocity of the center plane between two sectors(plane 3)was small.There was a recirculation zone at upstream of the center plane between two sectors(plane 3)when the swirl intensity was 0.7 and 0.9,whereas not one when the swirl intensity was 0.5.The above was induced by interactions.In addition,the velocity of plane 1,plane 3,and plane 5 when the venturi angle was 52°was smaller than that of 28°and 90°.
基金supported by the National Natural Science Foundation of China(Grant No.51306182)
文摘The low NOx emission technology has become an important feature of advanced aviation engine.A wide range of applications attempt to take advantage of the fact that staged combustion under lean-premixed-prevaporized(LPP)conditions can significantly cut down emission and improve combustion efficiency.This paper proposes a scheme with fuel centrally staged and multi-point injection.The mixing of fuel and air is improved,and the flame temperature is relative low in combustion zone,minimizing the formation of nitrogen oxides(NOx),especially thermal NOx.In terms of the field distribution of equivalence ratio and temperature obtained from Computational Fluid Dynamics(CFD),a chemical reactor network(CRN),including several different ideal reactor,namely perfectly stirred reactor(PSR)and plug flow reactor(PFR),is constructed to simulate the combustion process and predict pollution emission.The influences of the pilot equivalence ratio and percentage of pilot/main fuel on NOx and carbon monoxide(CO)emission were investigated by CRN model.The effects of the pilot fuel and primary fuel on pollution emission were investigated experimentally.Finally,the effects of pilot equivalence ratio and pilot fuel proportion on NOx emission were discussed in detail by comparing predict of CRN and experimental results.
基金supported by National Natural Science Foundation of China with project No.51306182
文摘Improvement on extinction and pollution emission have become one of the most prominent research topics in gas turbine.It is widely recognized that the fuel/air mixture distribution in the recirculation zone is a critical factor in improving lean blow-out(LBO) and ignition.This paper proposed a new low emission scheme with fuel staged centrally and hybrid injector to improve flameout and emission.A relative small amount of fuel enters into central pilot airblast atomizer burner and then atomized by inner swirl air.The remaining majority of fuel is directly injected into vane channels of the primary swirler through a series of holes located on the sidewall of the main stage.Only pilot stage is fueled under ignition and lean flameout condition.The uniformity of fuel/air mixture distribution in the primary zone of the new design decreases NOX emission,meanwhile the fuel air mixture in pilot recirculation zone is locally rich to improve flameout and ignition.Experimental investigation was conducted to compare the new scheme with baseline design of dual-swirler in terms of LBO and ignition characteristics under the same condition in a multi-sector combustor.It is found that the fuel-air ratio of ignition limit and LBO decrease with the reference velocity increasing.The experimental results also show that the new scheme successfully improve lean blow-out and broaden the operation range of the combustor.The experimental results indicated that the centrally staged scheme can widen the operation boundary of the combustor and can provide guidance for design and optimization of combustion chamber.
基金supported by the Project 91641109 and the Project 51406202 of National Natural Science Foundation of China
文摘In this paper,the flow field characteristics of a double-swirl low-emission combustor were analyzed by using Particle Imaging Velocimetry(PIV)technology in an optical three-sector combustor test rig.The interactions between sectors and the flow field structure were explained.The results illustrated that there was a big difference between the flow field structures of the middle sector and the side sector under the same pressure drop,which was mainly induced by the interactions between sectors.The interactions made the swirl intensity of the middle sector weaker than that of the side sector,which made the recirculation zone of the middle sector be smaller than that of the side sector.With the increase of swirler pressure drop,the jet velocity at the exit of the swirler,the jet expansion angle,the width of the recirculation zone and the recirculating speed of the central axis became larger,enhancing the interactions between air streams from middle sector and side sector.The flow velocity in the central plane between sectors was small,especially the radial velocity,mainly because of the loss of the swirl intensity by the interactions between flow field of adjacent sectors.The expansion angle determined the position of the vortex in the primary recirculation zone;the axial and radial position of the vortex move downstream and radial outward with the increase of the jet expansion angle.The results of the mechanism of flow field organization in this study can be used to support the design of new low-emission combustor.
基金supported by National Natural Science Foundation of China with project No.51306182
文摘The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real engine.In this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test section.The experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.
