A theoretical system has been developed to simulate the control of rotating stall. Circulating disturbance was appended to the system to suppress the developing of rotating wave. The control system has slight influenc...A theoretical system has been developed to simulate the control of rotating stall. Circulating disturbance was appended to the system to suppress the developing of rotating wave. The control system has slight influence on the systems critical B coefficient B cr . Self adaptive sector has been inserted into the proportion feed back control system to fit the nonlinear compressor system.展开更多
Abstract This article deals with application of grooved type casing treatment for suppression of spike stall in an isolated axial compressor rotor blade row. The continuous grooved casing treatment covering the whole ...Abstract This article deals with application of grooved type casing treatment for suppression of spike stall in an isolated axial compressor rotor blade row. The continuous grooved casing treatment covering the whole compressor circumference is of 1.8 mm in depth and located between 90% and 108% chord of the blade tip as measured from leading edge. The method of investigation is based on time-accurate three-dimensional full annulus numerical simulations for cases with and without casing treatment. Discretization of the Navier Stokes equations has been carried out based on an upwind second-order scheme and k-a-SST (Shear Stress Transport) turbulence modeling has been used for estimation of eddy viscosity. Time-dependent flow structure results for the smooth casing reveal that there are two criteria for spike stall inception known as leading edge spillage and trailing edge backftow, which occur at specific mass flow rates in near-stall conditions. In this case, two dominant stall cells of different sizes could be observed. The larger one is caused by the spike stall covering roughly two blade passages in the circumferential direction and about 25% span in the radial direction. Spike stall disturbances are accompanied by lower frequencies and higher amplitudes of the pressure signals. Casing treatment causes flow blockages to reduce due to allevi- ation of backflow regions, which in turn reduces the total pressure loss and increases the axial veloc- ity in the blade tip gap region, as well as tip leakage flow fluctuation at higher frequencies and lower amplitudes. Eventually, it can be concluded that the casing treatment of the stepped tip gap type could increase the stall margin of the compressor. This fact is basically due to retarding the movement of the interface region between incoming and tip leakage flows towards the rotor leading edge Diane and suttressing the reversed flow around the blade trailing edee.展开更多
In this paper,a high-order distortion model is proposed for analyzing the rotating stall inception process induced by inlet distortion in axial compressors.A distortion-generating screen in the compressor inlet is con...In this paper,a high-order distortion model is proposed for analyzing the rotating stall inception process induced by inlet distortion in axial compressors.A distortion-generating screen in the compressor inlet is considered.By assuming a quadratic function for the local flow total pressure-drop,the existing Mansoux model is extended to include the effects of static inlet distortion,and a new high-order distortion model is derived.To illustrate the effectiveness of the distortion model,numerical simulations are performed on an eighteenth-order model.It is demonstrated that long length-scale disturbances emerge out of the distorted background flow,and further induce the onset of rotating stall in advance.In addition,the circumferential non-uniform distribution and time evolution of the axial flow are also shown to be consistent with the existing features.It is thus shown that the high-order distortion model is capable of describing the transient behavior of stall inception and will contribute further to stall detection under inlet distortion.展开更多
Casing treatment is an effective technique in extending stall margin of axial and centrifugal compressor.However,its impacts on the stall behaviour of mixed-flow compressor are still not completely understood until no...Casing treatment is an effective technique in extending stall margin of axial and centrifugal compressor.However,its impacts on the stall behaviour of mixed-flow compressor are still not completely understood until now.To conquer this issue,unsteady full-annulus simulations were conducted to investigate the stall mechanism of a mixed-flow compressor with and without axial slot casing treatment(ASCT).The circumferential propagating speed of spike inception resolved by the numerical approach is 87.1%of the shaft speed,which is identical to the test data.The numerical results confirmed that the mixed-flow compressor fell into rotating stall via spike-type with and without ASCT.The flow structure of the spike inception was investigated at 50%design rotational speed.Instantaneous static pressure traces extracted upstream of the leading edge had shown a classic spiky wave.Furthermore,it was found that with and without ASCT,the mixed-flow compressor stalled through spike with the characteristic of tip leakage spillage at leading edge and tip leakage backflow from trailing edge,which is different from a fraction of the centrifugal compressor.The resultant phenomenon provides conoborating evidence for that unlike in axial-flow compressor,the addition of ASCT does not change the stall characteristics of the mixed-flow compressor.The flow structure that induced spike inception with ASCT is similar to the case with smooth casing.In the throttling process,tip leakage flow vortex had been involved in the formation of tornado vortices,with one end at the suction side,and the other end at the casing-side.The low-pressure region relevant to the downward spike is caused by leading-edge separation vortex or tornado vortex.The high-pressure region relevant to the upward spike is induced by blockage from the passage vortex.These results not only can provide guidance for the design of casing treatment in mixed-flow compressor,but also can pave the way for the stall waring in the highly-loaded compressors of next-generation aeroengines.展开更多
The inlet swirl distortion and non-uniform tip clearance have great effects on aero-engine performance and stall margin.In this paper,the effects of paired swirl distortion on the aerodynamic stability and stall incep...The inlet swirl distortion and non-uniform tip clearance have great effects on aero-engine performance and stall margin.In this paper,the effects of paired swirl distortion on the aerodynamic stability and stall inception of a single stage axial compressor with non-uniform tip clearance are quantitatively analyzed by using the swirl distortion descriptors.The experimental results show that the paired swirl distortion dominated by co-rotating swirl improves the stability of the axial compressor.For a single-stage axial compressor with eccentricity of 100%,the stall inception starts at the maximum tip clearance with clean inlet.The initial position of the stall inception is determined by the maximum tip clearance when the small intensity paired swirl distortion exists at the compressor inlet.As the swirl intensity increases,it shifts towards the position of the counter rotating swirl vortex core.The inlet swirl will not change the type of stall inception.展开更多
Partial surge is a type of instability inception in transonic compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub region.Previous studies illustrate that the frequency of...Partial surge is a type of instability inception in transonic compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub region.Previous studies illustrate that the frequency of partial surge is set by the Helmholtz frequency of the entire system,which motivates to propose a hypothesis that the system response performs an important role in the formation of partial surge.For further verification,a series of experiments are conducted to explore the link between the propagating of the partial surge and the system feedback in this study.In the first case,an additional test point is set on the wall of the plenum to detect the system response.Combining the flow behaviors inside the plenum with the disturbances in the rotor tip and stator hub/tip regions,the effects of the system feedback on the occurrence of the continuous disturbances and the rotating stall cells are illustrated.In the second case,a screen is mounted at the compressor outlet to prevent positive feedback from the plenum.The experimental results demonstrate that in the absence of system feedback,it is the occurrence of spike-type stall inception that leads to the flow instability instead of that of partial surge.In addition,three flow phenomena in the second case are discussed,including the occurrence of the single pulse,the unstable process during the stall evolution and the switch of instability inception.展开更多
文摘A theoretical system has been developed to simulate the control of rotating stall. Circulating disturbance was appended to the system to suppress the developing of rotating wave. The control system has slight influence on the systems critical B coefficient B cr . Self adaptive sector has been inserted into the proportion feed back control system to fit the nonlinear compressor system.
基金Financial support of the Aerodynamics and Compressible Turbomachinery Research Laboratory at Iran University of Science and Technology is highly appreciated
文摘Abstract This article deals with application of grooved type casing treatment for suppression of spike stall in an isolated axial compressor rotor blade row. The continuous grooved casing treatment covering the whole compressor circumference is of 1.8 mm in depth and located between 90% and 108% chord of the blade tip as measured from leading edge. The method of investigation is based on time-accurate three-dimensional full annulus numerical simulations for cases with and without casing treatment. Discretization of the Navier Stokes equations has been carried out based on an upwind second-order scheme and k-a-SST (Shear Stress Transport) turbulence modeling has been used for estimation of eddy viscosity. Time-dependent flow structure results for the smooth casing reveal that there are two criteria for spike stall inception known as leading edge spillage and trailing edge backftow, which occur at specific mass flow rates in near-stall conditions. In this case, two dominant stall cells of different sizes could be observed. The larger one is caused by the spike stall covering roughly two blade passages in the circumferential direction and about 25% span in the radial direction. Spike stall disturbances are accompanied by lower frequencies and higher amplitudes of the pressure signals. Casing treatment causes flow blockages to reduce due to allevi- ation of backflow regions, which in turn reduces the total pressure loss and increases the axial veloc- ity in the blade tip gap region, as well as tip leakage flow fluctuation at higher frequencies and lower amplitudes. Eventually, it can be concluded that the casing treatment of the stepped tip gap type could increase the stall margin of the compressor. This fact is basically due to retarding the movement of the interface region between incoming and tip leakage flows towards the rotor leading edge Diane and suttressing the reversed flow around the blade trailing edee.
基金co-supported by the National Major Scientific Instruments Development Project of China(No.61527811)the National Science Fund for Distinguished Young Scholars of China(No.61225014)+3 种基金the Guangdong Inovative Project(No.2013KJCX0009)the Guangdong Provice Natural Science Foundation(No.2014A030312005)the Guangdong Provice Key Laboratory of Biomedical Engineeringthe Space Intelligent Control Key Laboratory of Science and Technology for National Defense
文摘In this paper,a high-order distortion model is proposed for analyzing the rotating stall inception process induced by inlet distortion in axial compressors.A distortion-generating screen in the compressor inlet is considered.By assuming a quadratic function for the local flow total pressure-drop,the existing Mansoux model is extended to include the effects of static inlet distortion,and a new high-order distortion model is derived.To illustrate the effectiveness of the distortion model,numerical simulations are performed on an eighteenth-order model.It is demonstrated that long length-scale disturbances emerge out of the distorted background flow,and further induce the onset of rotating stall in advance.In addition,the circumferential non-uniform distribution and time evolution of the axial flow are also shown to be consistent with the existing features.It is thus shown that the high-order distortion model is capable of describing the transient behavior of stall inception and will contribute further to stall detection under inlet distortion.
基金The authors are grateful for the support of National Natural Science Foundation of China for the grant with Project No.51636001,No.51790510,and No.51922098the National Science and Technology Major Project(2017-11-0004-0017,2017-H-005-0018)The authors would also appreciate the kind help of Prof.Seume,and the German Research Foundation(DFG)for supporting the experiments as part of the Collaborative Research Centre 880(Sonderforschungsbereich SFB 880).
文摘Casing treatment is an effective technique in extending stall margin of axial and centrifugal compressor.However,its impacts on the stall behaviour of mixed-flow compressor are still not completely understood until now.To conquer this issue,unsteady full-annulus simulations were conducted to investigate the stall mechanism of a mixed-flow compressor with and without axial slot casing treatment(ASCT).The circumferential propagating speed of spike inception resolved by the numerical approach is 87.1%of the shaft speed,which is identical to the test data.The numerical results confirmed that the mixed-flow compressor fell into rotating stall via spike-type with and without ASCT.The flow structure of the spike inception was investigated at 50%design rotational speed.Instantaneous static pressure traces extracted upstream of the leading edge had shown a classic spiky wave.Furthermore,it was found that with and without ASCT,the mixed-flow compressor stalled through spike with the characteristic of tip leakage spillage at leading edge and tip leakage backflow from trailing edge,which is different from a fraction of the centrifugal compressor.The resultant phenomenon provides conoborating evidence for that unlike in axial-flow compressor,the addition of ASCT does not change the stall characteristics of the mixed-flow compressor.The flow structure that induced spike inception with ASCT is similar to the case with smooth casing.In the throttling process,tip leakage flow vortex had been involved in the formation of tornado vortices,with one end at the suction side,and the other end at the casing-side.The low-pressure region relevant to the downward spike is caused by leading-edge separation vortex or tornado vortex.The high-pressure region relevant to the upward spike is induced by blockage from the passage vortex.These results not only can provide guidance for the design of casing treatment in mixed-flow compressor,but also can pave the way for the stall waring in the highly-loaded compressors of next-generation aeroengines.
基金supported by National Science and Technology Major Project(Grant No.2017-II-0004-0017)。
文摘The inlet swirl distortion and non-uniform tip clearance have great effects on aero-engine performance and stall margin.In this paper,the effects of paired swirl distortion on the aerodynamic stability and stall inception of a single stage axial compressor with non-uniform tip clearance are quantitatively analyzed by using the swirl distortion descriptors.The experimental results show that the paired swirl distortion dominated by co-rotating swirl improves the stability of the axial compressor.For a single-stage axial compressor with eccentricity of 100%,the stall inception starts at the maximum tip clearance with clean inlet.The initial position of the stall inception is determined by the maximum tip clearance when the small intensity paired swirl distortion exists at the compressor inlet.As the swirl intensity increases,it shifts towards the position of the counter rotating swirl vortex core.The inlet swirl will not change the type of stall inception.
基金the support of National Natural Science Foundation of China(Nos.51706008,51636001,51976005 and 52006002)National Science and Technology Major Project,China(No.2017-Ⅱ-0005-0018)Aeronautics Power Foundation,China(No.6141B09050375)。
文摘Partial surge is a type of instability inception in transonic compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub region.Previous studies illustrate that the frequency of partial surge is set by the Helmholtz frequency of the entire system,which motivates to propose a hypothesis that the system response performs an important role in the formation of partial surge.For further verification,a series of experiments are conducted to explore the link between the propagating of the partial surge and the system feedback in this study.In the first case,an additional test point is set on the wall of the plenum to detect the system response.Combining the flow behaviors inside the plenum with the disturbances in the rotor tip and stator hub/tip regions,the effects of the system feedback on the occurrence of the continuous disturbances and the rotating stall cells are illustrated.In the second case,a screen is mounted at the compressor outlet to prevent positive feedback from the plenum.The experimental results demonstrate that in the absence of system feedback,it is the occurrence of spike-type stall inception that leads to the flow instability instead of that of partial surge.In addition,three flow phenomena in the second case are discussed,including the occurrence of the single pulse,the unstable process during the stall evolution and the switch of instability inception.