The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed,axial compressor.The flat-baffles with different span heights are used to simulate d...The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed,axial compressor.The flat-baffles with different span heights are used to simulate different distorted inflow cases.Compared with auto-correlation and root-mean-square analysis,cross-correlation analysis used to predict early stall warning does not depend on the distortion position.Hence,the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions.Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios,tip air injection was adopted as the actuator for adaptive feedback control.The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions.The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow.Thus,the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow,which frequently occurs in flight.展开更多
This paper considers effects of Rotating Inlet Distortion(RID)on a two-stage axial compressor and the stabilization effects of a casing treatment subjected to the considered RID.In multispool engines,the downstream co...This paper considers effects of Rotating Inlet Distortion(RID)on a two-stage axial compressor and the stabilization effects of a casing treatment subjected to the considered RID.In multispool engines,the downstream compressor suffers a RID when the upstream fan/compressor is in rotating stall.A controlled rotating sectional screen upstream of the compressor was adopted to generate the RID in different intensities,and co-or counter spinning direction compared with the rotor.The response of the compressor to inlet distortion was interpreted as the changes of stall margin.Results show that there are two peaks for the stall margin degradation where the distortion screen rotates near 20%and 70%of the rotor’s rotational frequency,respectively.Based on the measurements taken during the pre-stall process,it is suggested that the two frequencies are associated with the eigen frequencies of the compressor.Specifically,the first is associated with a stall precursor that is suspected as an initial disturbance existing in compressor and the second is related to a spike-type stall precursor.At last,a kind of Stall Precursor-Suppressed(SPS)casing treatment was applied to enhance the compressor stability in RID conditions.The result indicates that the stall margin is improved by 6%at an average level and there is nearly no efficiency loss caused by the application of such casing treatment.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
On the base of an assumed steady inlet circumferential total pressure distortion, three-dimensional time-dependent numerical simulations are conducted on an axial flow subsonic compressor rotor. The performances and f...On the base of an assumed steady inlet circumferential total pressure distortion, three-dimensional time-dependent numerical simulations are conducted on an axial flow subsonic compressor rotor. The performances and flow fields of a compressor rotor, either casing treated or untreated, are investigated in detail either with or without inlet pressure distortion. Results show that the circumferential groove casing treatment can expand the operating range of the compressor rotor either with or without inlet pressure distortion at the expense of a drop in peak isentropic efficiency. The casing treatment is capable of weakening or even removing the tip leakage vortex effectively either with or without inlet distortion. In clean inlet circumstances, the enhancement and forward movement of tip leakage vortex cause the untreated compressor rotor to stall. By contrast, with circumferential groove casing, the serious flow separation on the suction surface leads to aerodynamic stalling eventually. In the presence of inlet pressure distortion, the blade loading changes from passage to passage as the distorted inflow sector is traversed. Similar to the clean inlet circumstances, with a smooth wall casing, the enhancement and forward movement of tip leakage vortex are still the main factors which lead to the compressor rotor stalling eventually. When the rotor works trader near stall conditions, the blockage resulting from the tip leakage vortex in all the passages is very serious. Especially in several passages, flow-spillage is observed. Compared to the clean inlet circumstances, circumferential groove casing treatment can also eliminate the low energy zone in the outer end wall region effectively.展开更多
A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stabili...A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stability under circumferentially distorted inlet conditions.The inlet total pressure distribution downstream of the distortion screen is measured in experiments and employed for simulations which are implemented via time-space spectral method.The stall inception prediction results via the stability model indicate that the compressor with aft-loaded rotor not only performs better in terms of stability under uniform inlet,but also maintains a larger stability margin under circumferentially distorted inlet.The experiments for compressors with fore-loaded and aft-loaded rotor are respectively carried out.The results validate the reliability of numerical simulations and the predicted conclusion that the aft-loaded rotor is beneficial for compressor stability.Besides,the ability of the developed theoretical model for compressor stability prediction under circumferential distortions is confirmed.In addition,dynamic pressure signals at rotor tip measured in experiments illustrate that the circumferential distortion has little effect on the compressor stall pattern.展开更多
Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively evaluated....Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively evaluated.In the beginning,a small perturbation stability model for the periodic flow in compressors is proposed,referring to the governing equations of the Harmonic Balance Method.This stability model is validated on a single-stage low-speed compressor TA36 with uniform inlet flow.Then,the unsteady flow of TA36 with different inlet total temperature ramps and constant back pressure is simulated based on the Harmonic Balance Method.Based on these simulations,the compressor stability is analyzed using the proposed small perturbation model.Further,the Dynamic Mode Decomposition method is employed to accurately extract pressure oscillations.The two parameters of the temperature ramp,ramp rate and Strouhal number,are discussed in this paper.The results indicate the occurrence and extension of hysteresis loops in the rows,and a decrease in compressor stability with increasing ramp rate.Compressor performance is divided into two phases,stable and limit,based on the ramp rate.Furthermore,the model predictions suggest that a decrease in period length and an increase in Strouhal number lead to improved compressor stability.The DMD results imply that for compressors with inlet temperature ramp distortion,the increase of high-order modes and oscillations at the rotor tip is always the signal of decreasing stability.展开更多
A methodology has been developed to generate a non-uniform/distoited inlet flow field to test a gas turbine engine in ground test facilities.The distorted flow field is generated by positioning radial and circumferent...A methodology has been developed to generate a non-uniform/distoited inlet flow field to test a gas turbine engine in ground test facilities.The distorted flow field is generated by positioning radial and circumferential strips of varying widths upstream of the Aerodynamic Interface Plane.The interacting wakes from these strips are used to generate a given target flow field.The approximate superposition of these wakes is investigated and used to construct the strip arrangement which is subsequently validated by computing the flow field by solving the Navier-Stokes equations.The strip geometry designed using the present methodology is able to produce the target Mach number distribution with a root-mean-square error of 5.06%.展开更多
The present work is about the stall margin enhancement ability of a kind of stall precursor-suppressed(SPS) casing treatment when fan/compressor suffers from a radial total pressure inlet distortion.Experimental res...The present work is about the stall margin enhancement ability of a kind of stall precursor-suppressed(SPS) casing treatment when fan/compressor suffers from a radial total pressure inlet distortion.Experimental researches are conducted on a low-speed compressor with and without SPS casing treatment under radial distorted inlet flow of different levels as well as uniform inlet flow.The distorted flow fields of different levels are generated by annular distortion flow generators of different heights.The characteristic curves under these conditions are measured and analyzed.The results show that the radial inlet distortion could cause a stall margin loss from 2%to30%under different distorted levels.The SPS casing treatment could remedy this stall margin loss under small distortion level and only partly make up the stall margin loss caused by distortion in large level without leading to perceptible additional efficiency loss and obvious change of characteristic curves.The pre-stall behavior of the compressor is investigated to reveal the mechanism of this stall margin improvement ability of the SPS casing treatment.The results do show that this casing treatment delays the occurrence of rotating stall by weakening the pressure perturbations and suppressing the nonlinear amplification of the stall precursor waves in the compression system.展开更多
In order to explore the total-pressure distortion test assessment method for a turbofan engine, a Controlled Variable Double-Baffle Distortion Generator(CVDBDG) with a horizontal symmetry moving form was developed, wh...In order to explore the total-pressure distortion test assessment method for a turbofan engine, a Controlled Variable Double-Baffle Distortion Generator(CVDBDG) with a horizontal symmetry moving form was developed, which can adjust the steady-state and time–variant distortion separately in real time. The inlet total-pressure distortion test was conducted on an afterburner turbofan engine. The distortion parameters of CVDBDG and the instability characteristics of the engine were measured. The experimental data were modeled and analyzed by using back propagation artificial neural networks, and the work envelope of CVDBDG was obtained. Based on the analysis of the data on the engine’s instability, the properties of CVDBDG used for the stability assessment were preliminarily evaluated. The results show that CVDBDG can simulate both steady-state and time–variant distortions simultaneously in a range determined by three envelopes.Under the condition of symmetric double baffles, a critical depth of insertion exists, beyond which the symmetric baffles will generate an asymmetric flow field. In the case of double baffles, compared to a single baffle, the engine exhibited different instability characteristics. Based on CVDBDG, it is expected that more efficient engine stability and durability assessment methods can be developed.展开更多
基金co-supported by the National Natural Science Foundation of China(No.51922098)the National Science and Technology Major Project of China(No.2017-Ⅱ-0004-0017)the Special Fund for the Member of Youth Innovation Promotion Association of CAS(No.2018173).
文摘The adaptive feedback control of stability with circumferential inlet distortion has been experimentally investigated in a low-speed,axial compressor.The flat-baffles with different span heights are used to simulate different distorted inflow cases.Compared with auto-correlation and root-mean-square analysis,cross-correlation analysis used to predict early stall warning does not depend on the distortion position.Hence,the cross-correlation coefficient was used to monitor the stable status of the compressor and provide the feedback signal in the active control strategy when suffering from different distortions.Based on the stall margin improvement of tip air injection obtained under different distorted inflow cases and the sensitivity analysis of cross-correlation coefficients to injected momentum ratios,tip air injection was adopted as the actuator for adaptive feedback control.The digital signal processing controller was designed and applied to achieve adaptive feedback control in distorted inflow conditions.The results show that the adaptive feedback control of air injection nearly achieves the same stall margin improvement as steady air injection under different distortion intensities with a reduced injection mass flow.Thus,the proposed adaptive feedback control method is ideal for the engine operation with circumferential distorted inflow,which frequently occurs in flight.
基金supported by the National Natural Science Foundation of China(Nos.51822601,51790514 and 51906004)。
文摘This paper considers effects of Rotating Inlet Distortion(RID)on a two-stage axial compressor and the stabilization effects of a casing treatment subjected to the considered RID.In multispool engines,the downstream compressor suffers a RID when the upstream fan/compressor is in rotating stall.A controlled rotating sectional screen upstream of the compressor was adopted to generate the RID in different intensities,and co-or counter spinning direction compared with the rotor.The response of the compressor to inlet distortion was interpreted as the changes of stall margin.Results show that there are two peaks for the stall margin degradation where the distortion screen rotates near 20%and 70%of the rotor’s rotational frequency,respectively.Based on the measurements taken during the pre-stall process,it is suggested that the two frequencies are associated with the eigen frequencies of the compressor.Specifically,the first is associated with a stall precursor that is suspected as an initial disturbance existing in compressor and the second is related to a spike-type stall precursor.At last,a kind of Stall Precursor-Suppressed(SPS)casing treatment was applied to enhance the compressor stability in RID conditions.The result indicates that the stall margin is improved by 6%at an average level and there is nearly no efficiency loss caused by the application of such casing treatment.
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National Natural Science Foundation of China (10377013)
文摘On the base of an assumed steady inlet circumferential total pressure distortion, three-dimensional time-dependent numerical simulations are conducted on an axial flow subsonic compressor rotor. The performances and flow fields of a compressor rotor, either casing treated or untreated, are investigated in detail either with or without inlet pressure distortion. Results show that the circumferential groove casing treatment can expand the operating range of the compressor rotor either with or without inlet pressure distortion at the expense of a drop in peak isentropic efficiency. The casing treatment is capable of weakening or even removing the tip leakage vortex effectively either with or without inlet distortion. In clean inlet circumstances, the enhancement and forward movement of tip leakage vortex cause the untreated compressor rotor to stall. By contrast, with circumferential groove casing, the serious flow separation on the suction surface leads to aerodynamic stalling eventually. In the presence of inlet pressure distortion, the blade loading changes from passage to passage as the distorted inflow sector is traversed. Similar to the clean inlet circumstances, with a smooth wall casing, the enhancement and forward movement of tip leakage vortex are still the main factors which lead to the compressor rotor stalling eventually. When the rotor works trader near stall conditions, the blockage resulting from the tip leakage vortex in all the passages is very serious. Especially in several passages, flow-spillage is observed. Compared to the clean inlet circumstances, circumferential groove casing treatment can also eliminate the low energy zone in the outer end wall region effectively.
基金The research presented here was supported by the National Natural Science Foundation of China(Nos.52306036 and 52325602)the Science Center for Gas Turbine Project,China(Nos.P2022-A-II-002-001 and P2022-C-II-003-001)+3 种基金the Project funded by China Postdoctoral Science Foundation(No.2022M720346)the National Science and Technology Major Projectc,China(Nos.Y2022-II-0003-0006 and Y2022-II-0002-0005)Also,the research is supported by the Key Laboratory of Pre-Research Management Centre,China(No.6142702200101)the Fundamental Research Funds for the Central Universities,China(Nos.YWF-23-Q-1009 and YWF-23-Q-1065).
文摘A modified small perturbation stability prediction model for axial compressors with circumferential inlet distortions is established and applied to investigate the effect of fore/aft-loaded rotor on compressor stability under circumferentially distorted inlet conditions.The inlet total pressure distribution downstream of the distortion screen is measured in experiments and employed for simulations which are implemented via time-space spectral method.The stall inception prediction results via the stability model indicate that the compressor with aft-loaded rotor not only performs better in terms of stability under uniform inlet,but also maintains a larger stability margin under circumferentially distorted inlet.The experiments for compressors with fore-loaded and aft-loaded rotor are respectively carried out.The results validate the reliability of numerical simulations and the predicted conclusion that the aft-loaded rotor is beneficial for compressor stability.Besides,the ability of the developed theoretical model for compressor stability prediction under circumferential distortions is confirmed.In addition,dynamic pressure signals at rotor tip measured in experiments illustrate that the circumferential distortion has little effect on the compressor stall pattern.
基金supported by National Natural Science Foundation of China(NSFC Grant Nos.52306036,52325602)Science Center for Gas Turbine Project(P2022-A-Ⅱ-002-001,P2022-C-Ⅱ-003-001)+3 种基金Project funded by China Postdoctoral Science Foundation(2022M720346)National Science and Technology Major Project(Y2022-Ⅱ-0003-0006,Y2022-Ⅱ-0002-0005).Alsothe research is supported by the Key Laboratory of Pre-Research Management Centre(No.6142702200101)the Fundamental Research Funds for the Central Universities(YWF-23-Q-1009,YWF-23-Q-1065)。
文摘Based on a small perturbation stability model for periodic flow,the effects of inlet total temperature ramp distortion on the axial compressor are investigated and the compressor stability is quantitatively evaluated.In the beginning,a small perturbation stability model for the periodic flow in compressors is proposed,referring to the governing equations of the Harmonic Balance Method.This stability model is validated on a single-stage low-speed compressor TA36 with uniform inlet flow.Then,the unsteady flow of TA36 with different inlet total temperature ramps and constant back pressure is simulated based on the Harmonic Balance Method.Based on these simulations,the compressor stability is analyzed using the proposed small perturbation model.Further,the Dynamic Mode Decomposition method is employed to accurately extract pressure oscillations.The two parameters of the temperature ramp,ramp rate and Strouhal number,are discussed in this paper.The results indicate the occurrence and extension of hysteresis loops in the rows,and a decrease in compressor stability with increasing ramp rate.Compressor performance is divided into two phases,stable and limit,based on the ramp rate.Furthermore,the model predictions suggest that a decrease in period length and an increase in Strouhal number lead to improved compressor stability.The DMD results imply that for compressors with inlet temperature ramp distortion,the increase of high-order modes and oscillations at the rotor tip is always the signal of decreasing stability.
文摘A methodology has been developed to generate a non-uniform/distoited inlet flow field to test a gas turbine engine in ground test facilities.The distorted flow field is generated by positioning radial and circumferential strips of varying widths upstream of the Aerodynamic Interface Plane.The interacting wakes from these strips are used to generate a given target flow field.The approximate superposition of these wakes is investigated and used to construct the strip arrangement which is subsequently validated by computing the flow field by solving the Navier-Stokes equations.The strip geometry designed using the present methodology is able to produce the target Mach number distribution with a root-mean-square error of 5.06%.
基金supported by National Natural Science Foundation of China(51236001 and 51576008)National Basic Research Program of China(2012CB720201)+1 种基金Aeronautical Science Foundation of China(2014ZB51018)Fundamental Research Funds for the Central Universities
文摘The present work is about the stall margin enhancement ability of a kind of stall precursor-suppressed(SPS) casing treatment when fan/compressor suffers from a radial total pressure inlet distortion.Experimental researches are conducted on a low-speed compressor with and without SPS casing treatment under radial distorted inlet flow of different levels as well as uniform inlet flow.The distorted flow fields of different levels are generated by annular distortion flow generators of different heights.The characteristic curves under these conditions are measured and analyzed.The results show that the radial inlet distortion could cause a stall margin loss from 2%to30%under different distorted levels.The SPS casing treatment could remedy this stall margin loss under small distortion level and only partly make up the stall margin loss caused by distortion in large level without leading to perceptible additional efficiency loss and obvious change of characteristic curves.The pre-stall behavior of the compressor is investigated to reveal the mechanism of this stall margin improvement ability of the SPS casing treatment.The results do show that this casing treatment delays the occurrence of rotating stall by weakening the pressure perturbations and suppressing the nonlinear amplification of the stall precursor waves in the compression system.
基金supported by the Beijing Aeronautical Technology Research Center
文摘In order to explore the total-pressure distortion test assessment method for a turbofan engine, a Controlled Variable Double-Baffle Distortion Generator(CVDBDG) with a horizontal symmetry moving form was developed, which can adjust the steady-state and time–variant distortion separately in real time. The inlet total-pressure distortion test was conducted on an afterburner turbofan engine. The distortion parameters of CVDBDG and the instability characteristics of the engine were measured. The experimental data were modeled and analyzed by using back propagation artificial neural networks, and the work envelope of CVDBDG was obtained. Based on the analysis of the data on the engine’s instability, the properties of CVDBDG used for the stability assessment were preliminarily evaluated. The results show that CVDBDG can simulate both steady-state and time–variant distortions simultaneously in a range determined by three envelopes.Under the condition of symmetric double baffles, a critical depth of insertion exists, beyond which the symmetric baffles will generate an asymmetric flow field. In the case of double baffles, compared to a single baffle, the engine exhibited different instability characteristics. Based on CVDBDG, it is expected that more efficient engine stability and durability assessment methods can be developed.