The Relationship of Spike Stall and Hub Corner Separation in Axial Compressor

2020 ◽  
Vol 37 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Bin Jiang ◽  
Xiangtong Shi ◽  
Qun Zheng ◽  
Qingfang Zhu ◽  
Zhongliang Chen ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Leakage Flow ◽  
Separation Flow ◽  
Secondary Vortex ◽  
Tip Leakage Flow ◽  
Corner Separation ◽  
Tip Leakage

AbstractThe onset of spike stall induced by the interaction of hub corner separation flow with the tip leakage flow is investigated in detail by numerical method in this paper. The time resolved results indicate that the remarkable radial secondary flow from hub to tip near the trailing edge is formed when the compressor approaching rotating stall. The radial secondary flow is unstable and cross-passages propagates, which flows in and away out of the tip region periodically. The disturbance caused by radial secondary flow will influence the tip leakage flow directly by reforming the vortexes in blade tip region. A secondary vortex which comes from the radial migration of corner separation and is induced by the tip leakage vortex appears in the tip region. The simulation result demonstrates that the generation of the secondary vortex is an important symbol of blockage growth in the tip region at the stall inception phase. The disturbance produced by secondary vortex is an incentive of the leading edge overflow and the intensity of secondary vortex could be used as a criterion of rotating stall before leading edge spillage.

Numerical study of the unsteady behaviors and rotating stall inception process in a counter-rotating axial compressor

2016 ◽  
Vol 230 (14) ◽  
pp. 2716-2727 ◽  
Author(s):  
Xiaochen Mao ◽  
Bo Liu
Keyword(s):  
Numerical Study ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotating Stall ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Trailing Edge ◽  
Stall Inception ◽  
Tip Leakage

Unsteady computations of a counter-rotating axial compressor are performed and analyzed to investigate the unsteady behaviors in the compressor and the role of the tip leakage flow together with the rotating stall inception process. The results show that the oscillation on the pressure side is much stronger than that on the suction surface for both rotors, especially near the tip region where the trajectory of the tip leakage vortex (TLV) interacts with the blades most often. There exists a periodical leading edge spillage of the interface in rotor2 due to the unsteadiness of tip leakage flow (TLF) at near-stall condition. The blockage generated by the TLV increases dramatically due to the increasing strength of the TLV and the backflow phenomenon as the mass flow decreased. The appearance of the frequency components of 0.5 blade passing frequency (BPF) and 1.5BPF from 0.64BPF can be viewed as the rotating stall inception warning. The fluctuation strength of oscillation frequencies of 0.5BPF and 1.5BPF decreases rapidly from leading edge to trailing edge in rotor2, which indicates that the unsteady fluctuation of TLF at the leading edge in rotor2 is responsible for the stall inception of the compressor. Additionally, both the leading edge spillage and trailing edge backflow phenomena are observed for spike initiated rotating stall at stall point.

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.

Stall Inception and Development Process Due to Tip Leakage Flow in Axial Compressor Rotor Blades Row

2014 ◽  
Vol 30 (3) ◽  
pp. 307-313 ◽  
Author(s):  
R. Taghavi-Zenou ◽  
S. Abbasi ◽  
S. Eslami
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Axial Compressor ◽  
Leading Edge ◽  
Rotor Blades ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

ABSTRACTThis paper deals with tip leakage flow structure in subsonic axial compressor rotor blades row under different operating conditions. Analyses are based on flow simulation utilizing computational fluid dynamic technique. Three different circumstances at near stall condition are considered in this respect. Tip leakage flow frequency spectrum was studied through surveying instantaneous static pressure signals imposed on blades surfaces. Results at the highest flow rate, close to the stall condition, showed that the tip vortex flow fluctuates with a frequency close to the blade passing frequency. In addition, pressure signals remained unchanged with time. Moreover, equal pressure fluctuations at different passages guaranteed no peripheral disturbances. Tip leakage flow frequency decreased with reduction of the mass flow rate and its structure was changing with time. Spillage of the tip leakage flow from the blade leading edge occurred without any backflow in the trailing edge region. Consequently, various flow structures were observed within every passage between two adjacent blades. Further decrease in the mass flow rate provided conditions where the spilled flow ahead of the blade leading edge together with trailing edge backflow caused spike stall to occur. This latter phenomenon was accompanied by lower frequencies and higher amplitudes of the pressure signals. Further revolution of the rotor blade row caused the spike stall to eventuate to larger stall cells, which may be led to fully developed rotating stall.

The Influence of Tip Clearance Momentum Flux on Stall Inception in a High-Speed Axial Compressor

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Joshua D. Cameron ◽  
Matthew A. Bennington ◽  
Mark H. Ross ◽  
Scott C. Morris ◽  
Juan Du ◽  
...  
Keyword(s):  
Momentum Flux ◽  
High Speed ◽  
Axial Compressor ◽  
Leading Edge ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Axial Position ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage

Experimental and numerical studies were conducted to investigate tip-leakage flow and its relationship to stall in a transonic axial compressor. The computational fluid dynamics (CFD) results were used to identify the existence of an interface between the approach flow and the tip-leakage flow. The experiments used a surface-streaking visualization method to identify the time-averaged location of this interface as a line of zero axial shear stress at the casing. The axial position of this line, denoted xzs, moved upstream with decreasing flow coefficient in both the experiments and computations. The line was consistently located at the rotor leading edge plane at the stalling flow coefficient, regardless of inflow boundary condition. These results were successfully modeled using a control volume approach that balanced the reverse axial momentum flux of the tip-leakage flow with the momentum flux of the approach fluid. Nonuniform tip clearance measurements demonstrated that movement of the interface upstream of the rotor leading edge plane leads to the generation of short length scale rotating disturbances. Therefore, stall was interpreted as a critical point in the momentum flux balance of the approach flow and the reverse axial momentum flux of the tip-leakage flow.

scholarly journals Discussion: “Criteria for Spike Initiated Rotating Stall” (Vo, H. D., Tan, C. S., Greitzer, E. M., 2008, ASME J. Turbomach., 130, p. 011023)

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
A. Deppe ◽  
H. Saathoff ◽  
U. Stark
Keyword(s):  
Computational Study ◽  
Axial Flow ◽  
Leading Edge ◽  
Rotating Stall ◽  
Experimental Results ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Trailing Edge ◽  
Stall Inception ◽  
Tip Leakage

The paper “Criteria for Spike Initiated Rotating Stall” by Vo et al. (2008, ASME J. Turbomach., 130, p. 011023) provides a very important contribution to the understanding of spike-type stall inception in axial-flow compressors by demonstrating that spike-type disturbances are directly linked to the tip leakage flow of the rotor. The computational study of Vo et al. leads to the conclusion that two conditions have to be fulfilled simultaneously for the formation of spike-type stall: (i) axial backflow at the leading edge plane and (ii) axial backflow at the trailing edge plane. The objective of the present technical brief is to support these findings by corresponding experimental results.

Unsteady Investigation on Tip Flow Field and Rotating Stall in Counter-Rotating Axial Compressor

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Limin Gao ◽  
Ruiyu Li ◽  
Fang Miao ◽  
Yutong Cai
Keyword(s):  
Flow Field ◽  
Second Harmonic ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Stall Inception ◽  
Tip Leakage ◽  
Future Goals

Contra-rotating axial compressor/fan (CRAC) is a promising technology to meet the future goals aircraft industry. Massive time accurate simulations are performed to investigate rotating stall in CRAC containing two counter-rotating rotors. Particularly, the back pressure increasing with a very small step to avoid missing flow field transition from stability to instability. Due to the canceling of the stator, the instability of downstream rotor is more stronger. The present studies mostly focus on the downstream rotor. The tip leakage flow field is analyzed in detail under near stall condition, which indicates that a secondary leakage flow plays an important role in the unsteadiness of CRAC's unsteady flow field. The frequency analysis in the tip clearance of downstream rotor under multiple near stall conditions captured the transition of the second harmonic frequency which can be used as stall inception signal. Moreover, the rotating stall onset process in real CRAC is simulated on the numerical stall.

Numerical Investigation of the Behavior of Tip Leakage Flow in a Low-Speed Axial Compressor Rotor at Near-Stall Condition

2012 ◽  
Author(s):  
Zhenzhen Duan ◽  
Yangwei Liu ◽  
Lipeng Lu
Keyword(s):  
Axial Compressor ◽  
Rotating Stall ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Stall Inception ◽  
Low Speed ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Corner Vortex

In the present work, time-accurate simulations were performed to investigate the unsteady flow fields in the tip region of a low-speed large-scale axial compressor rotor at near-stall condition. Firstly, the steady performance characteristic of the rotor was obtained by steady simulations. Secondly, a series of unsteady simulations were carried out to investigate the physical processes as the rotor approaching stall and the role of complex tip flow mechanism on flow instability in the rotor. The characteristics of tip leakage vortex were compared between design condition and near-stall condition. Detailed analyses were then employed to emphasize the development of stall inception and the comprehensions of the internal flow field. Two flow phenomena, spillage at the leading edge and backflow at the trailing edge, are found beyond the flow solution limit, which are both linked to the tip leakage flow. And the breakdown of the tip leakage vortex has been captured. The flow visualization and the quantification of passage blockage expose that the tip leakage vortex and corner vortex contribute most to the total passage blockage. Therefore, they are considered to be the key flow structures contributing to the rotating stall. Further analyses indicate that, in the current rotor, the interaction of the tip leakage flow and the corner vortex is clarified to be the key factor that leads to the rotating stall. In addition, the very initial disturbances of stall inception are discussed. And the interaction of the boundary layer migration on the blade suction side and the tip leakage vortex also plays a significant role in the stall inception.

Effects of the Inlet Boundary Layer Thickness on the Rotating Stall in an Axial Compressor

2006 ◽  
Author(s):  
Minsuk Choi ◽  
Je Hyun Baek ◽  
Seong Hwan Oh ◽  
Dock Jong Ki
Keyword(s):  
Boundary Layer ◽  
Layer Thickness ◽  
Boundary Layer Thickness ◽  
Axial Compressor ◽  
Rotating Stall ◽  
High Load ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Corner Separation ◽  
Tip Leakage

A three-dimensional numerical simulation is conducted to study an effect of the inlet boundary layer thickness on the rotating stall in an axial compressor. The inlet boundary layer thickness has significant effects on the hub-corner-separation in the junction of the hub and suction surface. As the load is increased, the size of the hub-corner-separation is increased dramatically for the thick inlet boundary layer but it is diminished to be indistinguishable from the wake of the blade for the thin inlet boundary layer. The difference induced by different inlet conditions at high load should have affected characteristics of the rotating stall such as the inception process and propagation speed of the stall cells. For two cases of different inlet boundary layers, the numerical simulation is progressed as the flow coefficient is decreased until the rotating stall begins and then effects of the inlet boundary layer thickness on the rotating stall are analyzed by using the axial velocity history and the rotary total pressure distribution. For the thick inlet boundary layer, a pre-stall disturbance arises firstly in the hub-corner-separation and then in the tip leakage flow as the load is increased. For the thin inlet boundary layer, however, an asymmetric disturbance is initially generated in the tip region because of the corner-separation in the junction of the casing and suction surface. The disturbance of the tip leakage flow grows to be a stationary stall cell which is adhered to the blade passage by throttling process in case of the thick inlet boundary layer. When the stationary stall cell reach a critical size, this cell moves along the blade row and becomes a short-length-scale rotating stall. However, the rotating stall is not found at a smaller flow rate for the thin inlet boundary layer because the flow in the tip region is more energetic than that of its counterpart. In addition, it is found that the inlet boundary layer thickness has an effect on the cause of the initial disturbance which collapses the axi-symmetric flow under high load and the internal flow with a thick boundary layer on the casing is susceptible to the rotating stall.

scholarly journals Influence of Tip Clearance on Flow Characteristics of Axial Compressor

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1445
Author(s):  
Moru Song ◽  
Hong Xie ◽  
Bo Yang ◽  
Shuyi Zhang
Keyword(s):  
Flow Field ◽  
Flow Characteristics ◽  
Axial Compressor ◽  
Suction Side ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Tip Clearance Vortex

This paper studies the influence of tip clearance on the flow characteristics related to the performance. Based on full-passage numerical simulation with experimental validation, several clearance models are established and the performance curves are obtained. It is found that there exists an optimum clearance for the stable working range. By analyzing the flow field in tip region, the role of the tip leakage flow is illustrated. In the zero-clearance model, the separation and blockage along the suction side is the main reason for rotating stall. As the tip clearance is increased to the optimum value, the separation is suppressed by the tip leakage flow. However, with the continuing increasing of the tip clearance, the scale and strength of the tip clearance vortex is increased correspondingly. When the tip clearance is larger than the optimum value, the tip clearance vortex gradually dominates the flow field in the tip region, which can increase the unsteadiness in the tip region and trigger forward spillage in stall onset.

scholarly journals The Role of Tip Leakage Flow in Spike-Type Rotating Stall Inception

2017 ◽  
Author(s):  
M. Hewkin-Smith ◽  
G. Pullan ◽  
S. D. Grimshaw ◽  
E. M. Greitzer ◽  
Z. S. Spakovszky
Keyword(s):  
Maximum Flow ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Flow Coefficient ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Corner Separation ◽  
Tip Leakage

This paper describes the role of tip leakage flow in creating the leading edge separation necessary for the onset of spike-type compressor rotating stall. A series of unsteady multi-passage simulations, supported by experimental data, are used to define and illustrate the two competing mechanisms that cause the high incidence responsible for this separation: blockage from a casing-suction-surface corner separation and forward spillage of the tip leakage jet. The axial momentum flux in the tip leakage flow determines which mechanism dominates. At zero tip clearance, corner separation blockage dominates. As the clearance is increased, the leakage flow reduces the blockage, moving the stall flow coefficient to lower flow, i.e., giving a larger unstalled flow range. Increased clearance, however, means an increase in leakage jet momentum and the contribution to leakage jet spillage. There is thus a clearance above which jet spillage dominates in creating incidence, so the stall flow coefficient increases and the flow range decreases with clearance. As a consequence there is a clearance for maximum flow range; for the two rotors in this study, the value was approximately 0.5% chord. The chord-wise distribution of the leakage axial momentum is also important in determining stall onset. Shifting the distribution towards the trailing edge increases the flow range of a leakage jet dominated geometry and reduces the flow range of a corner separation dominated geometry. Guidelines are developed for flow range enhancement through control of tip leakage flow axial momentum magnitude and distribution. An example is given of how this might be achieved.

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