Comparative Study of Tip Injection in a Transonic and Subsonic Compressor

2021 ◽  
pp. 1-22
Author(s):  
Wei Wang ◽  
Liu Boxing ◽  
Lu Jinling ◽  
Jianjun Feng ◽  
Wuli Chu ◽  
...  
Keyword(s):  
Main Flow ◽  
Tip Clearance ◽  
Injection Velocity ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Injection Parameters ◽  
Stable Operating ◽  
Improved Stability ◽  
Underlying Mechanisms ◽  
Tip Injection

Abstract Discrete tip injection is an effective method to enhance stability of compressors. This study compares the effects of injection parameters on compressor performance and underlying mechanisms in two different compressors. The transonic compressor is studied using unsteady simulations and the subsonic compressor is mainly investigated with experiment. Results show that tip injection improves stable operating range by 35.6% and 77.9% for the transonic compressor and subsonic compressor, respectively, without decreasing compressor efficiency. The effects of circumferential coverage percentage and injector throat height on compressor stability are similar in the two compressors when the injection velocity is double the velocity of main flow. The optimal injector throat height which is normalized by the tip clearance size is the same for the two compressors, and the best circumferential coverage percentage for the subsonic compressor is lower than that in the transonic compressor. For the two compressors, the adaption of the main flow to the discrete tip injection is unsteady, and the hysteresis effect that the recovery of tip blockage lags behind the recovery of tip leakage vortex accounts for the improved stability using partial coverage of injection. The injection efficiency, which is defined to quantify the improved quality of the flow field in the injection domain, is proven to determine the stall limits by studying the effects of several injection parameters. The guidelines built in the subsonic compressor can be used in the transonic compressor to design tip injection, but the optimal values of some injection parameters should be reconfirmed.

scholarly journals Effects of Tip Leakage Flow on the Aerodynamic Performance and Stability of an Axial-Flow Transonic Compressor Stage

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4168
Author(s):  
Botao Zhang ◽  
Xiaochen Mao ◽  
Xiaoxiong Wu ◽  
Bo Liu
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Axial Flow ◽  
Leading Edge ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Transonic Compressor

To explain the effect of tip leakage flow on the performance of an axial-flow transonic compressor, the compressors with different rotor tip clearances were studied numerically. The results show that as the rotor tip clearance increases, the leakage flow intensity is increased, the shock wave position is moved backward, and the interaction between the tip leakage vortex and shock wave is intensified, while that between the boundary layer and shock wave is weakened. Most of all, the stall mechanisms of the compressors with varying rotor tip clearances are different. The clearance leakage flow is the main cause of the rotating stall under large rotor tip clearance. However, the stall form for the compressor with half of the designed tip clearance is caused by the joint action of the rotor tip stall caused by the leakage flow spillage at the blade leading edge and the whole blade span stall caused by the separation of the boundary layer of the rotor and the stator passage. Within the investigated varied range, when the rotor tip clearance size is half of the design, the compressor performance is improved best, and the peak efficiency and stall margin are increased by 0.2% and 3.5%, respectively.

Tip-Clearance and Secondary Flows in a Transonic Compressor Rotor

1999 ◽  
Vol 121 (4) ◽  
pp. 751-762 ◽  
Author(s):  
G. A. Gerolymos ◽  
I. Vallet
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Main Flow ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Computational Method ◽  
Tip Vortex ◽  
Computational Results ◽  
Transonic Compressor ◽  
Compressor Rotor

The purpose of this paper is to investigate tip-clearance and secondary flows numerically in a transonic compressor rotor. The computational method used is based on the numerical integration of the Favre-Reynolds-averaged three-dimensional compressible Navier–Stokes equations, using the Launder–Sharma near-wall k–ε turbulence closure. In order to describe the flowfield through the tip and its interaction with the main flow accurately, a fine O-grid is used to discretize the tip-clearance gap. A patched O-grid is used to discretize locally the mixing-layer region created between the jetlike flow through the gap and the main flow. An H–O–H grid is used for the computation of the main flow. In order to substantiate the validity of the results, comparisons with experimental measurements are presented for the NASA_37 rotor near peak efficiency using three grids (of 106, 2 X 106, and 3 X 106 points, with 21, 31, and 41 radial stations within the gap, respectively). The Launder–Sharma k–ε model underestimates the hub corner stall present in this configuration. The computational results are then used to analyze the interblade-passage secondary flows, the flow within the tip-clearance gap, and the mixing downstream of the rotor. The computational results indicate the presence of an important leakage-interaction region where the leakage-vortex after crossing the passage shock-wave mixes with the pressure-side secondary flows. A second trailing-edge tip vortex is also clearly visible.

Numerical Analysis of Transonic Compressor With Various Tip Clearance Gap

2016 ◽  
Author(s):  
Yasunori Sakuma ◽  
Toshinori Watanabe ◽  
Takehiro Himeno
Keyword(s):  
Tip Clearance ◽  
Leakage Flow ◽  
Numerical Instability ◽  
Tip Leakage Flow ◽  
Trailing Edge ◽  
Stall Margin ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Blade Tip ◽  
Edge Separation

Computational analysis has been conducted on the NASA Rotor 37 transonic compressor with various tip clearance gap heights. Using steady rotor-only analysis, the change in overall performance, basic flow characteristics, and near-casing phenomena have been carefully observed. The results have clarified that the peak efficiency of the compressor decreases almost linearly with the increase in gap height. Meanwhile, the stall margin was prone to deterioration in cases of significantly small or significantly large clearance gaps. The peak stall margin was attained when the gap was set to 75% of the original height. Focusing on the flow structures, the tip leakage flow and tip leakage vortex seemed to be dominant loss sources in the case of a large tip clearance gap. On the other hand, trailing edge separation at the blade tip was the major loss source in case of a small tip clearance gap. The difference in the near-casing flow structure also determined the onset process of numerical instability. In case of a large tip clearance gap, the advance of the interface between the main flow and tip leakage flow seemed to cause an accumulation of blockage in the region near the casing, possibly triggering the tip-initiated stall. In the case of a small tip clearance gap, interaction among the wall separation, blade tip trailing edge separation, and shockwave /boundary layer interaction was significant. These phenomena appeared to play a major role in the onset of numerical instability in the blade tip region.

Experimental and Numerical Investigation of the Flow Field in the Tip Region of an Axial Ventilation Fan

2004 ◽  
Vol 127 (2) ◽  
pp. 299-307 ◽  
Author(s):  
Xiaocheng Zhu ◽  
Wanlai Lin ◽  
Zhaohui Du
Keyword(s):  
Numerical Simulation ◽  
Experimental Measurement ◽  
Reverse Flow ◽  
Main Flow ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Direction Parallel ◽  
Tip Leakage ◽  
Ventilation Fan

The tip leakage flow in an axial ventilation fan with various tip clearances is investigated by experimental measurement and numerical simulation. For a low-rotating-speed ventilation fan with a large tip clearance, both experimental measurement and numerical simulation indicate that the leakage flow originating from the tip clearance along the chord rolls up into a three-dimensional spiral structure to form a leakage flow vortex. The mixing interaction between the tip leakage flow and the main flow produces a low axial velocity region in the tip region, which leads to blockage of the main flow. As the tip clearance increases, the tip leakage flow and the reverse flow become stronger and fully developed. In addition, the position of the first appearance of the tip leakage vortex moves further downstream in a direction parallel to the mid chord line.

scholarly journals Investigation of the tip injection for stall control in a transonic compressor with inlet distortion

2021 ◽  
Vol 5 ◽  
pp. 28-38
Author(s):  
Wenqiang Zhang ◽  
Mehdi Vahdati
Keyword(s):  
Experimental Studies ◽  
Flow Region ◽  
Main Flow ◽  
Test Case ◽  
Stall Margin ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Distorted Region ◽  
Tip Injection ◽  
Stall Control

Experimental studies have shown that tip injection upstream of the rotor can extend its operational range when subjected to circumferential inlet distortion. Typically, injectors are placed uniformly around the annulus. However, such arrangement consumes a large amount of high-pressure air and decreases the overall efficiency of the compression system. The aim of this paper is to minimise the amount of the injected air by determining the most effective circumferential location for the injector. In this study, NASA stage 35 was used as the test case. The experiment was conducted with a circumferential total pressure distortion of 120 degrees. In the first part of this paper, numerical simulations were compared against the experimental data and good match was obtained. In the second part, tip injection at three different positions were tested: the clean flow region (Position 1), the distorted region (Position 2) and the border between the clean and distorted regions (Position 3). It was found that a mild injection (0.66% of the main flow) at Position 2 and Position 3 can extend the stall margin by 1.8% and 2.7%, respectively. No obvious improvement was observed for the injection at Position 1. With a larger injection of 1.5% of main flow at Position 3, the stall margin improved further with no efficiency loss.

Tip-Clearance and Secondary Flows in a Transonic Compressor Rotor

1998 ◽  
Author(s):  
G. A. Gerolymos ◽  
I. Vallet
Keyword(s):  
Stokes Equations ◽  
Mixing Layer ◽  
Main Flow ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Computational Method ◽  
Tip Vortex ◽  
Computational Results ◽  
Transonic Compressor ◽  
Compressor Rotor

The purpose of this paper is to numerically investigate tip-clearance and secondary flows in a transonic compressor rotor. The computational method used is based on the numerical integration of the Favre-Reynolds-averaged 3-D compressible Navier-Stokes equations, using the Launder-Sharma near-wall k-ε turbulence closure. In order to accurately describe the flowfield through the tip and its interaction with the main flow, a fine O-grid is used to discretize the tip-clearance-gap. A patched O-grid is used to discretize locally the mixing-layer region created between the jet-like flow through the gap and the main flow. An H-O-H grid is used for the computation of the main flow. In order to substantiate the validity of the results comparisons with experimental measurements are presented for the NASA_37 rotor near peak efficiency using 3 grids (of 106, 2 × 106, and 3 × 106 points, with 21, 31, and 41 radial stations within the gap respectively). The Launder-Sharma k-ε model underestimates the hub corner stall present in this configuration. The computational results are then used to analyze the interblade-passage secondary flows, the flow within the tip-clearance gap and the mixing downstream of the rotor. The computational results indicate the presence of an important leakage-interaction-region where the leakage-vortex after crossing the passage shock-wave mixes with the pressure-side secondary flows. A second trailing-edge-tip-vortex is also clearly visible.

CFD Investigation on the Circumferential Grooves Casing Treatment of Transonic Compressor

2008 ◽  
Author(s):  
Xudong Huang ◽  
Haixin Chen ◽  
Song Fu
Keyword(s):  
Vortex Breakdown ◽  
Leading Edge ◽  
Tip Clearance ◽  
Groove Width ◽  
Mechanism Analysis ◽  
Stall Margin ◽  
Casing Treatment ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Edge Separation

The performance of NASA Rotor 37 with Circumferential Grooves Casing Treatment (CGCT) is studied with an in-house CFD code NSAWET. Based on the stall mechanism analysis, a number of CGCT configurations have been proposed and numerically tested. The computation results show that the stall mechanisms are strongly related with the width of tip clearance. With a small tip clearance, the stall process is dominated by the trailing edge separation, while the leading edge tip leakage vortex breakdown induced blockage causes stall in a large tip clearance configuration. Circumferential grooves at appropriate axial locations can be beneficial to the stall margin in these two types of stall processes. The effects of the groove width and depth are presented. The mechanisms of CGCT for different tip clearances are also discussed.

Effect of Tip Clearance Dimensions and Control of Unsteady Flows in a Multi-Stage High-Pressure Compressor

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
Nicolas Gourdain ◽  
Fabien Wlassow ◽  
Xavier Ottavy
Keyword(s):  
High Pressure ◽  
Unsteady Flows ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
High Pressure Compressor ◽  
Stable Operating ◽  
Overall Performance ◽  
Pressure Compressor

This paper describes the investigations performed to better understand unsteady flows that develop in a three-stage high-pressure compressor. More specifically, this study focuses on rotor-stator interactions and tip leakage flow effects on overall performance and aerodynamic stability. The investigation method is based on three-dimensional unsteady RANS simulations, considering the natural spatial periodicity of the compressor. Indeed, all information related to rotor-stator interactions can be computed. A comparison is first done with experimental measurements to outline the capacity of the numerical method to predict overall performance and unsteady flows. The results show that the simulation correctly estimates most flow features in the multistage compressor. Then numerical data obtained for three configurations of the same compressor are analyzed and compared. Configurations 1 and 2 consider two sets of tip clearance dimensions and a casing treatment based on a honeycomb design is applied for configuration 3. Detailed investigations of the flow at the same operating line show that the tip leakage flow is responsible for the loss of stability in the last stage. An increase by 30% of the tip clearance dimension dramatically reduces the stable operating range (by 40% with respect to the standard configuration). A modal analysis shows that the stall process in this case involves the perturbation of the flow in the last rotor by upstream stator wakes, leading to the development of a rotating instability. The control device designed and investigated in this study allows for reducing the sensitivity of the compressor to tip leakage flow by recovering the initial stable operating range.

Numerical Study on Interaction of Tip Synthetic Jet With Tip Leakage Flow in Centrifugal Impeller

2018 ◽  
Author(s):  
Wenlin Huang ◽  
Huijing Zhao ◽  
Zhiheng Wang ◽  
Guang Xi ◽  
Haijun Liu
Keyword(s):  
Leading Edge ◽  
Synthetic Jet ◽  
Main Flow ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Injection Angle ◽  
Tip Leakage ◽  
Blade Leading Edge

The synthetic jet, located at the shroud and close to the blade leading edge, is used to control the flow in a typical centrifugal impeller. The effects of the synthetic jet control and the interaction with the tip leakage flow are mainly investigated at the near-stall working point of impeller using the unsteady numerical analysis. The results indicate that, the effect of the synthetic jet with a small injection angle (15deg) is better when the excitation position is located over the main blade leading edge. However, the synthetic jet with a large injection angle (90deg) obtains a better result when the excitation position is located at the downstream of main blade leading edge. The synthetic jet with a larger velocity amplitude has a more remarkable effect on deflecting the main flow/tip leakage flow interface to the downstream direction. With typical parameters, the synthetic jet increases the circumferentially averaged streamwise location of the main flow/tip leakage flow interface by 12.5% compared with the case without a synthetic jet. The interaction between the tip leakage flow and synthetic jet makes the tip leakage flow out of the tip clearance with larger streamwise momentum, which is favorable to restrain the tip leakage flow to spill out the leading edge. Besides, the periodic blade loading drop is deflected to downstream direction and the flow fluctuation near the leading edge decrease significantly with the presence of synthetic jet.

Numerical Investigation on the Self-Induced Unsteadiness in Tip Leakage Flow for a Transonic Fan Rotor

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Juan Du ◽  
Feng Lin ◽  
Hongwu Zhang ◽  
Jingyi Chen
Keyword(s):  
Numerical Investigation ◽  
Driving Forces ◽  
Main Flow ◽  
Tip Clearance ◽  
The Self ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Blade Loading ◽  
Tip Leakage ◽  
Transonic Fan

A numerical investigation on the self-induced unsteadiness in tip leakage flow is presented for a transonic fan rotor. NASA Rotor 67 is chosen as the computational model. It is found that under certain conditions the self-induced unsteadiness can be originated from the interaction of two important driving “forces:” the incoming main flow and the tip leakage flow. Among all the simulated cases, the self-induced unsteadiness exists when the size of the tip clearance is equal to or larger than the design tip clearance. The originating mechanism of the unsteadiness is clarified through time-dependent internal flow patterns in the rotor tip region. It is demonstrated that when strong enough, the tip leakage flow impinges the pressure side of neighboring blade and alters the blade loading significantly. The blade loading in turn changes the strength of the tip leakage flow and results in a flow oscillation with a typical signature frequency. This periodic process is further illustrated by the time-space relation between the driving forces. A correlation based on the momentum ratio of tip leakage flow over the incoming main flow at the tip region is used as an indicator for the onset of the self-induced unsteadiness in tip leakage flow. It is discussed that the interaction between shock wave and tip leakage vortex does not initiate the self-induced unsteadiness, but might be the cause of other types of unsteadiness, such as broad-banded turbulence unsteadiness.

Sign in / Sign up

Export Citation Format

Share Document