Numerical investigation of influence of tip leakage flow on secondary flow in transonic centrifugal compressor at design condition

2015 ◽  
Vol 24 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Masanao Kaneko ◽  
Hoshio Tsujita
Keyword(s):  
Secondary Flow ◽  
Numerical Investigation ◽  
Centrifugal Compressor ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Transonic Centrifugal Compressor

Tip Leakage Flow Instability in a Centrifugal Compressor

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Teng Cao ◽  
Tadashi Kanzaka ◽  
Liping Xu ◽  
Tobias Brandvik
Keyword(s):  
Shear Layer ◽  
Centrifugal Compressor ◽  
Large Scale ◽  
Flow Instability ◽  
Leading Edge ◽  
Main Stream ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Unstable Flow ◽  
Tip Leakage

Abstract In this paper, an unsteady tip leakage flow phenomenon is identified and investigated in a centrifugal compressor with a vaneless diffuser at near-stall conditions. This phenomenon is associated with the inception of a rotating instability in the compressor. The study is based on numerical simulations that are supported by experimental measurements. The study confirms that the unstable flow is governed by a Kelvin–Helmholtz type instability of the shear layer formed between the main-stream flow and the tip leakage flow. The shear layer instability induces large-scale vortex roll-up and forms vortex tubes, which propagate circumferentially, resulting in measured pressure fluctuations with short wavelength and high amplitude which rotate at about half of the blade speed. The 3D vortex tube is also found to interact with the main blade leading edge, causing the reduction of the blade loading identified in the experiment. The paper also reveals that the downstream volute imposes a once-per-rev circumferential nonuniform back pressure at the impeller exit, inducing circumferential loading variation at the impeller inducer, and causing circumferential variation in the unsteady tip leakage flow.

PIV Maps of Tip Leakage and Secondary Flow Fields on a Low-Speed Turbine Blade Cascade With Moving End Wall

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
P. Palafox ◽  
M. L. G. Oldfield ◽  
J. E. LaGraff ◽  
T. V. Jones
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Field Measurements ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Low Speed ◽  
Tip Leakage ◽  
End Wall

New, detailed flow field measurements are presented for a very large low-speed cascade representative of a high-pressure turbine rotor blade with turning of 110deg and blade chord of 1.0m. Data were obtained for tip leakage and passage secondary flow at a Reynolds number of 4.0×105, based on exit velocity and blade axial chord. Tip clearance levels ranged from 0% to 1.68% of blade span (0% to 3% of blade chord). Particle image velocimetry was used to obtain flow field maps of several planes parallel to the tip surface within the tip gap, and adjacent passage flow. Vector maps were also obtained for planes normal to the tip surface in the direction of the tip leakage flow. Secondary flow was measured at planes normal to the blade exit angle at locations upstream and downstream of the trailing edge. The interaction between the tip leakage vortex and passage vortex is clearly defined, revealing the dominant effect of the tip leakage flow on the tip end-wall secondary flow. The relative motion between the casing and the blade tip was simulated using a motor-driven moving belt system. A reduction in the magnitude of the undertip flow near the end wall due to the moving wall is observed and the effect on the tip leakage vortex examined.

Numerical Study on Tip Clearance Effect on Performance of a Centrifugal Compressor

2002 ◽  
Author(s):  
Hark-Jin Eum ◽  
Shin-Hyoung Kang
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Specific Work ◽  
Tip Leakage Flow ◽  
Viscous Effects ◽  
Tip Leakage ◽  
Performance Reduction ◽  
Viscous Loss

Effects of tip clearance on through flows and performance of a centrifugal compressor impeller with six different tip clearances were numerically studied using CFX-TASCflow. The flow structures inside the impeller of a centrifugal compressor were visualized observing streamlines starting the leading edge of blade tips. The calculated results at the impeller exit were circumferential averaged for quantitative discussion. Flow, pressure and entropy contours at the impeller exit were largely influenced by the tip leakage flow. Tip clearance effect on the performance was decomposed into inviscid and viscous components using one-dimensional relations expressed in terms of the specific work reduction and the additional entropy generation. Both inviscid and viscous effects affected performance to similar extent, while efficiency drop was mainly influenced by viscous loss of the tip leakage flow. Performance reduction and efficiency drop due to tip clearance was proportional to the ratio of tip clearance to blade height. A simple model suggested in the present study predicts performance and efficiency drop quite successfully.

The Development of Turbine Exit Flow in a Swan-Necked Inter-Stage Diffuser

2003 ◽  
Author(s):  
R. J. Miller ◽  
R. W. Moss ◽  
R. W. Ainsworth ◽  
N. W. Harvey
Keyword(s):  
High Pressure ◽  
Secondary Flow ◽  
Leakage Flow ◽  
Turbine Stage ◽  
Tip Leakage Flow ◽  
Trailing Edge ◽  
Inlet Flow ◽  
Time Resolved ◽  
Tip Leakage ◽  
Numerical Predictions

This paper describes both the migration and dissipation of flow phenomena downstream of a transonic high-pressure turbine stage. The geometry of the HP stage exit duct considered is a swan-necked diffuser similar to those likely to be used in future engine designs. The paper contains results both from an experimental programme in a turbine test facility and from numerical predictions. Experimental data was acquired using three fast-response aerodynamic probes capable of measuring Mach number, whirl angle, pitch angle, total pressure and static pressure. The probes were used to make time-resolved area traverses at two axial locations downstream of the rotor trailing edge. A 3D time-unsteady viscous Navier-Stokes solver was used for the numerical predictions. The unsteady exit flow from a turbine stage is formed from rotor-dependent phenomena (such as the rotor wake, the rotor trailing edge recompression shock, the tip-leakage flow and the hub secondary flow) and vane-rotor interaction dependant phenomena. This paper describes the time-resolved behaviour and three-dimensional migration paths of both of these phenomena as they convect downstream. It is shown that the inlet flow to a downstream vane is dominated by two corotating vortices, the first caused by the rotor tip-leakage flow and the second by the rotor hub secondary flow. At the inlet plane of the downstream vane the wake is extremely weak and the radial pressure gradient is shown to have caused the majority of the high loss wake fluid to be located between the mid-height of the passage and the casing wall. The structure of the flow indicates that between a high pressure stage and a downstream vane simple two-dimensional blade row interaction does not occur. The results presented in this paper indicate that the presence of an upstream stage is likely to significantly alter the structure of the secondary flow within a downstream vane. The paper also shows that vane-rotor interaction within the upstream stage causes a 10° circumferential variation in the inlet flow angle of the 2nd stage vane.

Nonaxisymmetric Study of Tip Leakage Flow in a Centrifugal Compressor With a Volute During Stall Process

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Ce Yang ◽  
Botai Su ◽  
Li Fu ◽  
Hang Zhang
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Leading Edge ◽  
Work Capacity ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
High Static Pressure ◽  
Circumferential Nonuniformity

Abstract Tip leakage flow (TLF) patterns, which affect compressor performance, are closely related to compressor stability. To date, minimal attention has been given to circumferential nonuniformity of the TLF in a centrifugal compressor with a nonaxisymmetric volute structure. In this study, the circumferential difference of the TLF in a centrifugal compressor with a volute during the stall process is analyzed. The circumferential nonuniformity of tip leakage vortex (TLV) trajectories, loading distribution near the tip, and distance between the TLV core and the leading edge (LE) of splitter blades were also investigated. It is shown that in the circumferential direction, there are two peaks associated with the angle (α) between the TLV trajectory of the seven main blades and the axial direction. As the stall process progresses, the blade whose LE is affected by the high static pressure band (PP) induced by the volute tongue (VT) loses its work capacity first and the α difference between this blade and the other blades increases. In addition, the tip loading and TLF velocity of the blade whose LE is affected by the high static pressure band induced by the VT are at a minimum, and the flow loss in the tip clearance is higher. There is a phenomenon of the TLV breakdown. When the blade trailing edge (TE) is located in the low static pressure region, TLV streamlines appear as a significant turn at the breakdown point. However, the TLV streamlines at other circumferential positions do not exhibit this phenomenon.

Effect of Recirculation Device on Performance of High Pressure Ratio Centrifugal Compressor

2010 ◽  
Author(s):  
Hideaki Tamaki
Keyword(s):  
High Pressure ◽  
Centrifugal Compressor ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Operating Range ◽  
High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. A recirculation device, which consists of a bleed slot, an upstream slot and an annular cavity connecting both slots, is often applied to them. The author developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, a recirculation device was applied, the benefits of its application ensuring. This paper discusses how the recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3D calculations. It is reported that the interaction between shock and tip leakage vortex is one of the primary causes of stall inception in the impeller. Analysis of shock and tip leakage flow behavior leads to an understanding of the basic mechanism of the enhancement of operating range by the recirculation device. Hence this study focuses on the effect of the recirculation devices on the shock and tip leakage flow. Steady 3D calculations were performed and the effect of the recirculation device was clarified. The bleed slot of the recirculation device works in a similar way to circumferential grooves applied to axial compressors. It reduces the blade loading in the impeller tip region. And hence the velocity of tip leakage flow exiting the bleed slot becomes lower compared with that without the recirculation device. The flow through the bleed slot impinges on the tip leakage flow originated upstream and blocks the extension of the tip leakage flow. It also deflects the trajectory of the tip leakage vortex. In addition to these effects, the bleed slot removes the fluid near the casing. The shock moves downstream due to the reduction of the blockage. All these effects induced by the recirculation device are considered to lead to the suppression of the extension of blockage and to contribute to the enhancement of the compressor operating range.

Experimental and numerical investigation of the unsteady tip leakage flow in axial compressor cascade

2013 ◽  
Vol 22 (2) ◽  
pp. 103-110 ◽  
Author(s):  
Chengqing Li ◽  
Tingfeng Ke ◽  
Jingxuan Zhang ◽  
Hongwu Zhang ◽  
Weiguang Huang
Keyword(s):  
Numerical Investigation ◽  
Axial Compressor ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Tip Leakage
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