Effects of tip air injection on the aerodynamic stability of an axial flow compressor with total pressure distortion

2021 ◽  
pp. 095441002110375
Author(s):  
Baofeng Tu ◽  
Xinyu Zhang ◽  
Liang Li ◽  
Jun Hu
Keyword(s):  
Total Pressure ◽  
Critical Role ◽  
Axial Flow ◽  
Air Injection ◽  
Aerodynamic Stability ◽  
Insertion Depth ◽  
Stall Margin ◽  
Low Speed ◽  
Inlet Distortion ◽  
The Stability

The compressor is a critical component that determines the aerodynamic stability of an aero-engine. Total pressure inlet distortion decreases the thrust and shrinks the stability margin, thus inducing severe performance degradation or even flameout. Generally, tip air injection is used to reduce the adverse influence of total pressure inlet distortion on the aerodynamic stability. In the present work, an experimental investigation on the effects of tip air injection on the stability of a two-stage low-speed axial compressor with total pressure inlet distortion was carried out. A flat baffle generated the total pressure distortion at the inlet of the compressor. The stall margin of the compressor was reduced significantly by the total pressure distortion. When the dimensionless insertion depth of the flat baffle was 0.45, the stall margin decreased to 11.4%. Under the total pressure inlet distortion, tip air injection effectively improved the distortion resistance capability of the compressor. The circumferential layout of the nozzle played a critical role in the stability expansion effect of tip air injection under the inlet flow condition of the total pressure distortion. The modal wave disturbance was likely to occur in the distortion-affected region (the low-pressure region and the mixing region). Tip air injection did not inhibit the generation of the modal wave but restrained the development of the modal wave into the stall cell. It improved the low-speed compressor’s tolerance to the modal wave and allowed a higher amplitude modal wave to occur.

Numerical Investigation of Effect of Inlet Distortion on Compressor Flow Field and Stability

2017 ◽  
Author(s):  
HaoGuang Zhang ◽  
Kang An ◽  
Feng Tan ◽  
YanHui Wu ◽  
WuLi Chu
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Total Pressure ◽  
Tip Clearance ◽  
Numerical Work ◽  
Stall Margin ◽  
Numerical Investigations ◽  
Inlet Distortion ◽  
Compressor Rotor ◽  
The Stability

The compressor aerodynamic design is conducted under the condition of clean inlet in general, but a compressor often operates under the condition of inlet distortion in the practical application. It has been proven by a lot of experimental and numerical investigations that inlet distortion can decrease the performance and stability of compressors. The circumferential or radial distorted inlet in mostly numerical investigations is made by changing the total pressure and total temperature in the inlet ring surface of the compressors. In most of inlet distortion experiments, distorted inlets are usually created by using wire net, flashboards, barriers or the generator of rotating distortion. The fashion of generating distorted inlet for experiment is different from that for numerical simulation. Consequently, the flow mechanism of affecting the flow field and stability of a compressor with distorted inlet for experiment is partly different than that for numerical simulation. In the numerical work reported here, the inlet distortion is generated by setting some barriers in the inlet ring surface of an axial subsonic compressor rotor. Two kinds of distorted inlet are investigated to exploring the effect of distorted range on the flow field and stability of the compressor with ten-passage unsteady numerical method. The numerical results show that the inlet distortions not only degrade the total pressure and efficiency of the compressor rotor, but also decrease the stability of the rotor. The larger the range of distorted inlet is, the stronger the adverse effect is. The comprehensive stall margin for the inlet distortion of 24 degrees and 48 degrees of ten-passages is reduced about 3.35% and 5.88% respectively. The detailed analysis of the flow field in the compressor indicates that the blockage resulted from tip clearance leakage vortex (TLV) and the flow separation near the suction surfaces of some blades tip for distorted inlet is more serious than that resulted from TLV for clean inlet. Moreover, the larger the range of distorted inlet is, the larger the range of the blockage is. The analysis of unsteady flow shows that during this process, which is that one rotor blade passes through the region affected by the distorted inlet, the range of the blockage in the rotor passage increases first, then reduces, and increases last.

An Experimental Investigation About the Effect of the Partial Casing Treatment on a Transonic Axial-Flow Compressor Performance Under Inlet Distortion

2012 ◽  
Author(s):  
Maoyi Li ◽  
Wei Yuan ◽  
Xizhen Song ◽  
Yajun Lu ◽  
Zhiping Li ◽  
...  
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Peak Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Axial Flow Compressor ◽  
Inlet Distortion ◽  
Flow Compressor ◽  
Total Pressure Ratio

The traditional annulus casing treatment often pays the price of lowered efficiency for improving the stall margin of a compressor under inlet distortion. In view of the unsymmetry of the inlet flow-field of compressors, partial casing treatment was used to control the flow in a transonic axial-flow compressor with arc-skewed-slots deployed at different circumferential positions under inlet distortion. The experimental results indicate that when the partial casing treatment is arranged on the undistorted and distorted sectors, the stall margin is enhanced by 8.02%, with the relative peak efficiency improved simultaneously by 2.143%, compared with the case of solid casing at 98% rotating speed. By contrast, the traditional casing treatment increases the stall-margin by 23.13%, but decreases the relative peak efficiency by 0.752%. By analyzing dynamic and static experimental data, the mechanism underlying the partial casing treatment was also studied in detail here. The disturbances of inlet flow were restrained by annulus casing treatment, nevertheless the total pressure ratio was decreased obviously in the distorted sector. As a result, the stall-margin is improved, but the relative peak efficiency is decreased too. When the partial casing treatment was arranged on the undistortded and distorted sectors, the stall disturbances was thereby restrained. So the stall margin was enhanced. In addition, the total pressure ratio was improved by the partial casing treatment in the distorted and transition sectors, and thus the relative peak efficiency was also increased markedly.

scholarly journals Experimental and Numerical Investigation on Effects of the Steam Ingestion on the Aerodynamic Stability of an Axial Compressor

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1416
Author(s):  
Baofeng Tu ◽  
Xinyu Zhang ◽  
Jun Hu
Keyword(s):  
Boundary Layer ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Axial Flow ◽  
Stability Margin ◽  
Negative Influence ◽  
Suction Surface ◽  
Aerodynamic Stability ◽  
Stall Margin ◽  
Low Speed

In order to investigate the influence of steam ingestion on the aerodynamic stability of a two-stage low-speed axial-flow compressor, multiphase flow numerical simulation and experiment were carried out. The total pressure ratio and stall margin of the compressor was decreased under steam ingestion. When the compressor worked at 40% and 53% of the nominal speed, the stall margin decreased, respectively, by 1.5% and 6.3%. The ingested steam reduced the inlet Mach number and increased the thickness of the boundary layer on the suction surface of the blade. The low-speed region around the trailing edge of the blade was increased, and the flow separation region of the boundary layer on the suction surface of the blade was expanded; thus, the compressor was more likely to enter the stall state. The higher the rotational speed, the more significant the negative influence of steam ingestion on the compressor stall margin. The entropy and temperature of air were increased by steam. The heat transfer between steam and air was continuous in compressor passages. The entropy of the air in the later stage was higher than that in the first stage; consequently, the flow loss in the second stage was more serious. Under the combined action of steam ingestion and counter-rotating bulk swirl distortion, the compressor stability margin loss was more obvious. When the rotor speed was 40% and 53% of the nominal speed, the stall margin decreased by 6.3% and 12.64%, respectively.

A Parametric Study of the Effects of Inlet Distortion on Fan Aerodynamic Stability

2018 ◽  
Author(s):  
Wenqiang Zhang ◽  
Mehdi Vahdati
Keyword(s):  
Boundary Layer ◽  
Measured Data ◽  
Rotating Stall ◽  
Aerodynamic Stability ◽  
Stall Margin ◽  
Turbofan Engines ◽  
Inlet Distortion ◽  
Recent Trends ◽  
Fan Blade ◽  
The Stability

The performance and aerodynamic stability of fan blades operating in a circumferentially non-uniform inlet flow is a key concern in the design of turbofan engines. With the recent trends in the design of civil engines with shorter inlet ducts (such as low-speed fans), or boundary layer ingesting engines, quick and reliable modelling of rotor/distortion interactions is becoming very important. The aim of this paper is to study the effects of inlet distortions on the aerodynamic stability of a fan blade and to identify the parameters that have a major impact on the stability of the blade. NASA rotor 67, for which a significant amount of measured data is available, was used for this study. In the first part of this study, the behavior of the fan with inlet distortion at near stall condition is analyzed, and it is shown how rotating stall is triggered. In the second part of this study, unsteady simulations with inlet distortion were performed to study how parameters, such as exit duct length and distortion strength, influence the stall margin of the blade.

A Parametric Study of the Effects of Inlet Distortion on Fan Aerodynamic Stability

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Wenqiang Zhang ◽  
Mehdi Vahdati
Keyword(s):  
Boundary Layer ◽  
Measured Data ◽  
Rotating Stall ◽  
Aerodynamic Stability ◽  
Stall Margin ◽  
Turbofan Engines ◽  
Inlet Distortion ◽  
Recent Trends ◽  
Fan Blade ◽  
The Stability

The performance and aerodynamic stability of fan blades operating in a circumferentially nonuniform inlet flow is a key concern in the design of turbofan engines. With the recent trends in the design of civil engines with shorter inlet ducts (such as low-speed fans), or boundary layer ingesting engines, quick and reliable modeling of rotor/distortion interactions is becoming very important. The aim of this paper is to study the effects of inlet distortions on the aerodynamic stability of a fan blade and to identify the parameters that have a major impact on the stability of the blade. NASA rotor 67, for which a significant amount of measured data is available, was used for this study. In the first part of this study, the behavior of the fan with inlet distortion at near stall (NS) condition is analyzed, and it is shown how rotating stall is triggered. In the second part of this study, unsteady simulations with inlet distortion were performed to study how exit duct length influences the stall margin of the blade.

The Effect of Inlet Distortion on the Performance Characteristics of a Centrifugal Compressor

1983 ◽  
Vol 105 (2) ◽  
pp. 223-230 ◽  
Author(s):  
I. Ariga ◽  
N. Kasai ◽  
S. Masuda ◽  
Y. Watanabe ◽  
I. Watanabe
Keyword(s):  
Centrifugal Compressor ◽  
Total Pressure ◽  
Performance Characteristics ◽  
Performance Tests ◽  
Velocity Measurements ◽  
Test Rig ◽  
Low Speed ◽  
Inlet Distortion ◽  
Surge Margin ◽  
The Given

The present paper concerns itself with the effects of total pressure (and thus velocity) distortion on performance characteristics and surge margin of centrifugal compressors. Both radial and circumferential distortions were investigated. The performance tests as well as the velocity measurements within the impeller passages were carried out with a low-speed compressor test rig with the inlet honeycomb as the distortion generators and compared with the case of “no distortion” as a datum. The results indicated that the inlet distortion exerted unfavorable influences on the efficiency and the surge margin of the given compressor, though the influence of the radial distortion was much stronger than that of the circumferential one. Various distortion indices were further examined in order to correlate the performance to the inlet distortion.

A Study of Influences of Inlet Total Pressure Distortions On Clearance Flow in an Axial Compressor

2021 ◽  
Author(s):  
Guoming Zhu ◽  
Xiaolan Liu ◽  
Bo Yang ◽  
Moru Song
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Leading Edge ◽  
Stall Margin ◽  
Flow Cells ◽  
Static Pressure Distribution ◽  
Speed Flow ◽  
Clearance Flow ◽  
The Stability

Abstract The rotating distortion generated by upstream wakes or low speed flow cells is a kind of phenomenon in the inlet of middle and rear stages of an axial compressor. Highly complex inflow can obviously affect the performance and the stability of these stages, and is needed to be considered during compressor design. In this paper, a series of unsteady computational fluid dynamics (CFD) simulations is conducted based on a model of an 1-1/2 stage axial compressor to investigate the effects of the distorted inflows near the casing on the compressor performance and the clearance flow. Detailed analysis of the flow field has been performed and interesting results are concluded. The distortions, such as total pressure distortion in circumferential and radial directions, can block the tip region so that the separation loss and the mixing loss in this area are increased, and the efficiency and the total pressure ratio are dropped correspondingly. Besides, the distortions can change the static pressure distribution near the leading edge of the rotor, and make the clearance flow spill out of the rotor edge more easily under near stall condition, especially in the cases with co-rotating distortions. This phenomenon can be used to explain why the stall margin is deteriorated with nonuniform inflows.

scholarly journals Recess Vane Passive Stall Control

1992 ◽  
Author(s):  
M. Ziabasharhagh ◽  
A. B. McKenzie ◽  
R. L. Elder
Keyword(s):  
Experimental Investigation ◽  
Axial Flow ◽  
Operating Efficiency ◽  
Stall Margin ◽  
Casing Treatment ◽  
Inlet Distortion ◽  
Stall Margin Improvement ◽  
Stage Characteristic ◽  
Stall Control

An experimental investigation has been carried out on the influence of a vaned recessed casing treatment on the stall margin improvement of axial flow fans with different hub to tip ratio, with and without inlet distortion. The inlet distortion tests were conducted on a 0.5 hub to tip ratio fan and significant increases in the flow range with only small drops in operating efficiency were observed. The clean flow tests were conducted on higher hub to tip ratio fans (0.7 and 0.9). In each case the stage characteristic was compared with the results obtained with a solid casing. Significant increases in the flow range, with only modest or no loss in operating efficiency, were observed for optimum configurations at both diameter ratios.

scholarly journals A 3D Rotating Stall Stability Model for Axial Flow Compressor

1997 ◽  
Author(s):  
Ren-Jing Cao ◽  
Sheng Zhou
Keyword(s):  
Axial Flow ◽  
Rotating Stall ◽  
3D Flow ◽  
Aerodynamic Stability ◽  
Stall Margin ◽  
Spatial Variables ◽  
Stability Behavior ◽  
Stability Model ◽  
Flow Effects ◽  
Flow Compressor

Rotating stall phenomenon is usually characterized by 3D aerodynamic stability behavior. The earlier models mainly considered the flow effects in terms of 1D and 2D spatial variables. In order to involve the characteristics of the 3D flow of the compressor, it is necessary to improve the existing rotating stall stability models and further develop the models to consider the effects of the 3D disturbance. In this paper, a new aerodynamic stability model concerning the effects of a radial disturbance produced by the compressor, and explaining more mechanisms about the aerodynamic stability of compressor is presented. Using the developed rotating stall stability model, the stall margins are calculated and compared to experimental data for two axial flow compressors. The calculated results show that the developed 3D rotating stall stability model gives better stall margin prediction than that by the 2D model.

Effects of Circumferential Inlet Distortion on the Performance of a Transonic Fan Together With the Impact of Tip Injection

2016 ◽  
Author(s):  
Hossein Khaleghi ◽  
Reza Jalaly
Keyword(s):  
Flow Field ◽  
Axial Flow ◽  
Test Case ◽  
Inlet Distortion ◽  
Distorted Region ◽  
And Performance ◽  
Tip Injection ◽  
The Stability ◽  
Transonic Fan ◽  
The Impact

Half-annulus unsteady numerical simulations have been conducted with a 60-deg total pressure circumferential distortion in a transonic axial-flow fan. The effects of inlet distortion on the performance, stability and flow field of the test case are investigated and analyzed. Results show that the incidence angles are reduced when the blades are entering into the distorted region. Conversely, distortion increases the incidence angles onto the blades when they are leaving the distorted section. Results further reveal that the time-averaged flow field at the tip of the blade is similar with and without distortion. However, the distortion applied is found to have detrimental effects on both the stability and performance. The impacts of both annular and discrete tip injection on the endwall flow field are further studied in the current work. It is shown that endwall injection reduces the incidence angles onto the blades. Consequently, the passage shock and the leakage flow are pushed rearward, which postpones stall initiation.

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