The Tip and Hub Leakage Flow of a Repeated Two Stage Compressor

2002 ◽  
Author(s):  
Songtao Wang ◽  
Zhongqi Wang
Keyword(s):  
Tip Vortex ◽  
Leakage Flow ◽  
Streamwise Direction ◽  
Suction Surface ◽  
Two Stage ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Weak Part ◽  
Wall Flow ◽  
End Wall

End wall flow of a repeated two stage compressor at design and choke condition were studied by numerical simulation. The vortex near the hub depends on the traverse pressure gradient and sheer force induced by the hub rotation. At the design and the choke condition the hub leakage vortex is the dominant secondary flow. The position and trajectory of the tip leakage vortex at design and choke condition were also studied. At the design condition the tip leakage vortex traverse the blade channel and impinge on the middle chord of the suction surface of the adjacent blade. At the near choke condition the tip leakage vortex would go downstream along the streamwise direction. The composition of the tip vortex was also studied. It is clearly to distinguish the strong and weak part of the tip leakage vortex for design condition while at the near choke condition there is no evident weak part of the tip leakage vortex.

Physical Explanations of Tip Leakage Flow Field in an Axial Compressor Rotor

1998 ◽  
Author(s):  
Masahiro Inoue ◽  
Masato Furukawa ◽  
Kazuhisa Saiki ◽  
Kazutoyo Yamada
Keyword(s):  
Boundary Layer ◽  
Vortex Core ◽  
Leakage Flow ◽  
Surface Boundary ◽  
Suction Surface ◽  
Surface Boundary Layer ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Compressor Rotor ◽  
Vortex Lines

Structure of a tip leakage flow field in an axial compressor rotor has been investigated by detailed numerical simulations and appropriate post-processing. Physical explanations of the structure are made in terms of vortex-core identification, normalized helicity, vortex-lines, limiting streamlines, etc. The onset of the discrete tip leakage vortex is located on the suction surface at some distance from the leading edge. The vortex core with high vorticity is generated from a shear layer between the leakage jet flow and the main flow. The streamlines in the leakage flow are coiling around the vortex core. All the vortex-lines in the tip leakage vortex core link to ones in the suction surface boundary layer. The other vortex-lines in the suction surface boundary layer link to the vortex-lines in the pressure surface boundary layer and in the casing wall boundary layer. There are two mechanisms to reduce intensity of the tip leakage vortex: one is reduction of discharged vorticity caused by the linkage of vortex-lines between the suction surface and casing wall boundary layers, and another is diffusion of vorticity from the tip leakage vortex. Relative motion of the endwall has a substantial influence on the structure of the leakage flow field. In the case of a compressor rotor, it intensifies streamwise vorticity of the leakage vortex but reduces leakage flow loss.

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.

Rotor-Tip Flow Fields Near Inception Point of Rotating Instability in an Axial-Flow Fan

2011 ◽  
Author(s):  
Takahiro Nishioka ◽  
Toshio Kanno ◽  
Kiyotaka Hiradate
Keyword(s):  
Vortex Breakdown ◽  
Rotor Blades ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Stall Inception ◽  
Tip Leakage ◽  
Rotating Instability ◽  
End Wall ◽  
Stagger Angle

Stall inception patterns at three stagger-angle settings for the highly loaded rotor blades were experimentally investigated in a low-speed axial-flow fan. Rotor-tip flow fields were also numerically investigated to clarify the mechanism behind the stall inception from a rotating instability. The rotating instability is confirmed near stall condition at the high stagger-angle settings for the highly loaded rotor blades as same as that for the moderate loaded rotor blades. The rotating instability is induced by an interaction between the incoming flow, the reversed tip-leakage flow, and the end-wall backflow from the trailing edge. At the high stagger-angle settings for the rotor blades, the interface between the incoming flow and the reversed tip leakage flow becomes parallel to the leading edge plane near and at the stall condition. Moreover, the tip leakage flow spills from the leading edge of the adjacent blade at the stall condition. The changes in the end-wall flow at the rotor tip are consistent with the criteria for the spike initiation suggested by Vo et al. and Hah et al. However, the short length-scale stall cell is not observed at the high stagger-angle settings. The tip-leakage vortex breakdown is confirmed at the three stagger-angle settings. The end-wall blockage induced by the tip-leakage vortex breakdown influences the development of the stall cell. Moreover, the development of the three-dimensional separation vortex induced by the tip-leakage vortex breakdown seems to be one of the criteria for spike-type stall inception.

Analysis of Vortical Flow Field in a Propeller Fan by LDV Measurements and LES—Part I: Three-Dimensional Vortical Flow Structures

2001 ◽  
Vol 123 (4) ◽  
pp. 748-754 ◽  
Author(s):  
Choon-Man Jang ◽  
Masato Furukawa ◽  
Masahiro Inoue
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Vortex ◽  
Vortical Flow ◽  
Axial Fan ◽  
Suction Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Edge Separation

Three-dimensional structures of the vortical flow field in a propeller fan with a shroud covering only the rear region of its rotor tip have been investigated by experimental analysis using laser Doppler velocimetry (LDV) measurements and by numerical analysis using a large eddy simulation (LES) in Part I of the present study. The propeller fan has a very complicated vortical flow field near the rotor tip compared with axial fan and compressor rotors. It is found that three vortex structures are formed near the rotor tip: the tip vortex, the leading edge separation vortex, and the tip leakage vortex. The tip vortex is so strong that it dominates the flow field near the tip. Its formation starts from the blade tip suction side near the midchord. Even at the design condition the tip vortex convects nearly in the tangential direction, thus impinging on the pressure surface of the adjacent blade. The leading edge separation vortex develops close along the tip suction surface and disappears in the rear region of the rotor passage. The tip leakage vortex is so weak that it does not affect the flow field in the rotor.

Experimental Study on the Three-Dimensional Flow Within a Compressor Cascade With Tip Clearance: Part II—The Tip Leakage Vortex

1993 ◽  
Vol 115 (3) ◽  
pp. 444-450 ◽  
Author(s):  
S. Kang ◽  
C. Hirsch
Keyword(s):  
Vortex Core ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Vortex Center ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage

An analysis of the experimental data of a linear compressor cascade with tip clearance is presented with special attention to the development of the tip leakage vortex. A method for determining the tip vortex core size, center position, and vorticity or circulation from the measured data is proposed, based on the assumption of a circular tip vortex core. It is observed that the axial velocity profile passing through the tip vortex center is wavelike. The vorticity of the tip vortex increases rapidly near the leading edge and reaches its highest values at a short distance downstream, from which it gradually decreases. In the whole evolution, its size is growing and its center is moving away from both the suction surface and the endwall, approximately in a linear way.

scholarly journals Experimental Study on the Three Dimensional Flow Within a Compressor Cascade With Tip Clearance: Part II — The Tip Leakage Vortex

1992 ◽  
Author(s):  
Shun Kang ◽  
Ch. Hirsch
Keyword(s):  
Vortex Core ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Clearance ◽  
Tip Vortex ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Vortex Centre

An analysis of the experimental data of a linear compressor cascade with tip clearance is presented with special attention to the development of the tip leakage vortex. A method for determining the tip vortex core size, centre position and vorticity or circulation from the measured data is proposed, based on the assumption of a circular tip vortex core. It is observed that the axial velocity profile passing through the tip vortex centre is wake-like. The vorticity of the tip vortex increases rapidly near the leading edge and reaches its highest values at a short distance downstream, from which it gradually decreases. In the whole evolution, its size is growing and its centre is moving away from both the suction surface and the endwall, approximately in a linear way.

scholarly journals Influences of groove-type casing treatment on the tip leakage flow behaviour in linear compressor cascades at different tip clearances: influence of single groove at mid-chord

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 277
Author(s):  
Masanao Kaneko
Keyword(s):  
Flow Behaviour ◽  
Tip Clearance ◽  
Leakage Flow ◽  
Compressor Cascade ◽  
Tip Leakage Flow ◽  
Suction Surface ◽  
Linear Compressor ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Large Expansion

In this study, the influences of the single groove installed at the mid-chord – which is known to have a large expansion effect on the stable operating flow range of low-speed axial compressors – on the flow behaviour and the loss generation in a linear compressor cascade were investigated numerically at different tip clearances. Reynolds-averaged Navier–Stokes simulations of the incompressible flow in the test cascade were performed, with the computed results clarifying the following remarkable phenomena, which are common to both small and large tip-clearance cases. The single groove locally weakens the tip leakage flow by the decrease in the blade loading and the streaming of the flow near the blade pressure side into the groove, consequently reducing the distance between the tip leakage vortex and the blade suction surface. Meanwhile, although the groove decreases the loss due to the tip leakage vortex generated from the blade leading edge, the loss generation in the entire cascade passage is almost the same as that in the cascade without the groove due to the additional loss generation resulting from the presence of the groove.

Study on Effect of Axial Overlap on Tip Leakage Flow Structure in Tandem Bladed Low Speed Axial Flow Compressor

2019 ◽  
Author(s):  
Ajey Singh ◽  
Chetan S. Mistry
Keyword(s):  
Flow Structure ◽  
Stream Flow ◽  
Axial Flow ◽  
Main Stream ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Minimum Number ◽  
Wall Flow ◽  
End Wall

Abstract This paper discusses the effect of axial overlap on tip leakage flow behavior in a low speed tandem bladed axial compressor. Tandem bladed axial flow compressors provide an efficient way of obtaining a higher pressure rise with minimum number of stages as compared to a conventional design. The single stage tandem rotor compressor is designed to achieve a stage loading coefficient of 1.04 and flow coefficient of 0.9. A tip clearance of 3% (of span) is provided for the current study and it is maintained constant for all axial overlap configuration studies. A computational study of the designed stage was performed to investigate the behavior of tip leakage flow with different axial overlap and its effect on the overall performance of the stage. The application of tandem blading is only justified by prescribing high aerodynamic loading on both blades which increases the concern for associated tip leakage and corner separation losses. The study reveals the interaction of tip leakage flow from the fore and aft blade with the end wall flow and its influence on the main stream flow. The presence of an aft blade behind the fore seeks additional caution for optimum management of tip leakage flow. The leakage flows from the individual blades tend to roll up along with the shroud boundary layer resulting in the formation of momentum deficit fluid in the flow passage and at exit of rotors. The penetration of momentum deficit fluid in the main stream flow is directly related to the leakage flow structure from the fore and aft blade and also their interaction with the end wall flow. The axial overlap is seen to influence the leakage flow structure in two different ways. Firstly, it is observed that the initiation of tip leakage vortex of aft blade shifts from 30% to 10% of chord measured from leading edge, as axial overlap varies from 5% to −5% of chord in the tip region respectively. Secondly, a change in axial overlap also causes a change in passage geometry of the tandem blade interaction zone which has a first order influence on the mass flow rate through it. The accelerated flow through the passage geometry sustains high loading on the aft blade. It can also be utilized for mitigating the low momentum incoming fluid resulting from the mixing of tip leakage and end wall flow. The appropriate realization of these two effects has a potential to minimize the losses occurring due to tip leakage flow in the tandem compressor rotor and to achieve the benefit of higher loading with minimum number of stages.

Large-Scale Simulation of the Clocking Impact of 2D Combustor Profile on a Two Stage High Pressure Turbine

2014 ◽  
Author(s):  
Thomas E. Dyson ◽  
David B. Helmer ◽  
James A. Tallman
Keyword(s):  
High Pressure ◽  
Large Scale ◽  
High Pressure Turbine ◽  
Cfd Simulations ◽  
Two Stage ◽  
Substantial Impact ◽  
Sliding Mesh ◽  
Wall Flow ◽  
End Wall ◽  
Film Flows

This paper presents sliding-mesh unsteady CFD simulations of high-pressure turbine sections of a modern aviation engine in an extension of previously presented work [1]. The simulation included both the first and second stages of a two-stage high-pressure turbine. Half-wheel domains were used, with source terms representing purge and film flows. The end-wall flow-path cavities were incorporated in the domain to a limited extent. The passage-to-passage variation in thermal predictions was compared for a 1D and 2D turbine inlet boundary condition. Substantial impact was observed on both first and second stage vanes despite the mixing from the first stage blade. Qualitative and quantitative differences in surface temperature distributions were observed due to different ratios between airfoil counts in the two domains.

Aerodynamic Interaction Between Incoming Vortex and Tip Leakage Flow in a Turbine Cascade

2018 ◽  
Author(s):  
Kai Zhou ◽  
Chao Zhou
Keyword(s):  
Numerical Study ◽  
Aerodynamic Performance ◽  
Leakage Flow ◽  
Computational Domain ◽  
Turbine Cascade ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Swirl Generator ◽  
Swirling Vortex

In turbines, secondary vortices and tip leakage vortices develop and interact with each other. In order to understand the flow physics of vortices interaction, the effects of incoming vortex on the downstream tip leakage flow are investigated in terms of the aerodynamic performance in a turbine cascade. Experimental, numerical and analytical methods are used. In the experiment, a swirl generator was used upstream near the casing to generate the incoming vortex, which interacted with the tip leakage vortex in the turbine cascade. The swirl generator was located at ten different pitchwise locations to simulate the quasi-steady effects. In the numerical study, a Rankine-like vortex was defined at the inlet of the computational domain to simulate the incoming swirling vortex. Incoming vortices with opposite directions were investigated. The vorticity of the positive incoming swirling vortex has a large vector in the same direction as that of the tip leakage vortex. In the case of the positive incoming swirling vortex, the vortex mixes with the tip leakage vortex to form one vortex near the tip as it transports downstream. The vortices interaction reduces the vorticity of the flow near the tip, as well as the loss by making up for the streamwise momentum within the tip leakage vortex core. In contrast, the negative incoming swirling vortex has little effects on the tip leakage vortex and the loss. As the negative incoming swirling vortex transports downstream, it is separated from the tip leakage vortex and forms two vortices. A triple-vortices-interaction kinetic analytical model and one-dimensional mixing model are proposed to explain the mechanism of vortex interaction on the aerodynamic performance.

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