Three-dimensional spatial-temporal evolution and dynamics of the tip leakage vortex in an oil–gas multiphase pump

An experimental investigation concerning tip flow field unsteadiness was performed for a high-performance, state-of-the-art transonic compressor rotor. Casing-mounted high frequency response pressure transducers were used to indicate both the ensemble averaged and time varying flow structure present in the tip region of the rotor at four different operating points at design speed. The ensemble averaged information revealed the shock structure as it evolved from a dual shock system at open throttle to an attached shock at peak efficiency to a detached orientation at near stall. Steady three-dimensional Navier Stokes analysis reveals the dominant flow structures in the tip region in support of the ensemble averaged measurements. A tip leakage vortex is evident at all operating points as regions of low static pressure and appears in the same location as the vortex found in the numerical solution. An unsteadiness parameter was calculated to quantify the unsteadiness in the tip cascade plane. In general, regions of peak unsteadiness appear near shocks and in the area interpreted as the shock-tip leakage vortex interaction. Local peaks of unsteadiness appear in mid-passage downstream of the shock-vortex interaction. Flow field features not evident in the ensemble averaged data are examined via a Navier-Stokes solution obtained at the near stall operating point.

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The Behavior of the Casing Boundary Layer With the Presence of Tip Leakage Vortex

Volume 2A: Turbomachinery ◽

10.1115/gt2018-75916 ◽

2018 ◽

Cited By ~ 2

Author(s):

Xi Nan ◽

Feng Lin ◽

Takehiro Himeno ◽

Toshinori Watanabe

Keyword(s):

Boundary Layer ◽

Skin Friction ◽

Three Dimensional ◽

Pressure Rise ◽

Rotating Stall ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Transonic Compressor ◽

Flow Loss ◽

Produce Flow

Casing boundary layer effectively places a limit on the pressure rise capability achievable by the compressor. The separation of the casing boundary layer not only produce flow loss but also closely related to the compressor rotating stall. The motivation of this paper is to present a viewpoint that the casing boundary layer should be paid attention to in parallel with other flow factors on rotating stall trigger. This paper illustrates the casing boundary layer behavior by displaying its separation phenomena with the presence of tip leakage vortex at different flow conditions. Skin friction lines and the corresponding absolute streamlines are used to demonstrate the three-dimensional flow patterns on and near the casing. The results depict a Saddle, a Node and several tufts of skin friction lines dividing the passage into four zones. The tip leakage vortex is enfolded within one of the zones by the separated flows. All the flows in each blade passage are confined within the passage as long as the compressor is stable. The casing boundary layer of a transonic compressor is also examined in the same way, which results in qualitatively similar zonal flows that enfolds the tip leakage vortex. This research develops a new way to study the casing boundary layer in rotating compressors. The results may provide a first-principle based explanation to stalling mechanisms for compressors that are casing sensitive.

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Education Committee Best Paper of 1995 Award: Methods of Classical Mechanics Applied to Turbulence Stresses in a Tip Leakage Vortex

Journal of Turbomachinery ◽

10.1115/1.2840917 ◽

1996 ◽

Vol 118 (4) ◽

pp. 622-629 ◽

Cited By ~ 11

Author(s):

J. G. Moore ◽

S. A. Schorn ◽

J. Moore

Keyword(s):

Stress Tensor ◽

Reynolds Stress ◽

Classical Mechanics ◽

Three Dimensional ◽

Surface Model ◽

Reynolds Stresses ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Stress Tensors ◽

Principal Directions

Moore et al. measured the six Reynolds stresses in a tip leakage vortex in a linear turbine cascade. Stress tensor analysis, as used in classical mechanics, has been applied to the measured turbulence stress tensors. Principal directions and principal normal stresses are found. A solid surface model, or three-dimensional glyph, for the Reynolds stress tensor is proposed and used to view the stresses throughout the tip leakage vortex. Modeled Reynolds stresses using the Boussinesq approximation are obtained from the measured mean velocity strain rate tensor. The comparison of the principal directions and the three-dimensional graphic representations of the strain and Reynolds stress tensors aids in the understanding of the turbulence and what is required to model it.

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Spatial–Temporal Evolution of Tip Leakage Vortex in a Mixed-Flow Pump With Tip Clearance

Journal of Fluids Engineering ◽

10.1115/1.4042756 ◽

2019 ◽

Vol 141 (8) ◽

Cited By ~ 48

Author(s):

Yabin Liu ◽

Lei Tan

Keyword(s):

Temporal Evolution ◽

Flow Instability ◽

Dominant Frequency ◽

Oscillation Period ◽

Relative Vorticity ◽

Tip Clearance ◽

Mixed Flow ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Flow Pump

Tip clearance in pump induces tip leakage vortex (TLV), which interacts with the main flow and leads to instability of flow pattern and decrease of pump performance. In this work, the characteristics of TLV in a mixed-flow pump are investigated by the numerical simulation using shear stress transport (SST) k–ω turbulence model with experimental validation. The trajectory of the primary tip leakage vortex (PTLV) is determined, and a power function law is proposed to describe the intensity of the PTLV core along the trajectory. Spatial–temporal evolution of the TLV in an impeller revolution period T can be classified into three stages: splitting stage, developing stage, and merging stage. The TLV oscillation period TT is found as 19/160 T, corresponding to the frequency 8.4 fi (fi is impeller rotating frequency). Results reveal that the TLV oscillation is intensified by the sudden pressure variation at the junction of two adjacent blades. On analysis of the relative vorticity transport equation, it is revealed that the relative vortex stretching item in Z direction is the major source of the splitting and shedding of the PTLV. The dominant frequency of pressure and vorticity fluctuations on the PTLV trajectory is 8.4 fi, same as the TLV oscillation frequency. This result reveals that the flow instability in the PTLV trajectory is dominated by the oscillation of the TLV. The blade number has significant effect on pressure fluctuation in tip clearance and on blade pressure side, because the TLV oscillation period varies with the circumferential length of flow passage.

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Unsteady Flow Behavior due to Breakdown of Tip Leakage Vortex in an Axial Compressor Rotor at Near-Stall Condition

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/2000-gt-0666 ◽

2000 ◽

Cited By ~ 15

Author(s):

Masato Furukawa ◽

Kazuhisa Saiki ◽

Kazutoyo Yamada ◽

Masahiro Inoue

Keyword(s):

Unsteady Flow ◽

Three Dimensional ◽

Axial Compressor ◽

Surface Boundary ◽

Pressure Side ◽

Suction Surface ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Pressure Surface ◽

Compressor Rotor

The unsteady flow nature caused by the breakdown of the tip leakage vortex in an axial compressor rotor at near-stall conditions has been investigated by unsteady three-dimensional Navier-Stokes flow simulations. The simulations show that the spiral-type breakdown of the tip leakage vortex occurs inside the rotor passage at the near-stall conditions. Downstream of the breakdown onset, the tip leakage vortex twists and turns violently with time, thus interacting with the pressure surface of the adjacent blade. The motion of the vortex and its interaction with the pressure surface are cyclic. The vortex breakdown causes significant changes in the nature of the tip leakage vortex, which result in the anomalous phenomena in the time-averaged flow fields near the tip at the near-stall conditions: no rolling-up of the leakage vortex downstream of the rotor, disappearance of the casing wall pressure trough corresponding to the leakage vortex, large spread of the low-energy fluid accumulating on the pressure side, and large pressure fluctuation on the pressure side. As the flow rate is decreased, the movement of the tip leakage vortex due to its breakdown becomes so large that the leakage vortex interacts with the suction surface as well as the pressure one. The interaction with the suction surface gives rise to the three-dimensional separation of the suction surface boundary layer.

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Experimental Study on the Three-Dimensional Flow Within a Compressor Cascade With Tip Clearance: Part I—Velocity and Pressure Fields

Journal of Turbomachinery ◽

10.1115/1.2929270 ◽

1993 ◽

Vol 115 (3) ◽

pp. 435-443 ◽

Cited By ~ 40

Author(s):

S. Kang ◽

C. Hirsch

Keyword(s):

Three Dimensional ◽

Leading Edge ◽

Surface Flow ◽

Tip Clearance ◽

Tip Vortex ◽

Compressor Cascade ◽

Three Dimensional Flow ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Dimensional Flow

Experimental results from a study of the three-dimensional flow in a linear compressor cascade with stationary endwall at design conditions are presented for tip clearance levels of 1.0, 2.0, and 3.3 percent of chord, compared with the no-clearance case. In addition to five-hole probe measurements, extensive surface flow visualizations are conducted. It is observed that for the smaller clearance cases a weak horseshoe vortex forms in the front of the blade leading edge. At all the tip gap cases, a multiple tip vortex structure with three discrete vortices around the midchord is found. The tip leakage vortex core is well defined after the midchord but does not cover a significant area in traverse planes. The presence of the tip leakage vortex results in the passage vortex moving close to the endwall and the suction side.

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Three-Dimensional Turbulent Flow in the Tip Region of an Axial Compressor Rotor Passage at a Near Stall Condition

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery ◽

10.1115/2001-gt-0331 ◽

2001 ◽

Author(s):

Hongwei Ma ◽

Haokang Jiang

Keyword(s):

Turbulent Flow ◽

Large Scale ◽

Three Dimensional ◽

Axial Flow ◽

Leading Edge ◽

Rotating Stall ◽

Suction Surface ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Compressor Rotor

This paper presents an experimental study of the three-dimensional turbulent flow field in the tip region of an axial flow compressor rotor passage at a near stall condition. The investigation was conducted in a low-speed large-scale compressor using a 3-component Laser Doppler Velocimetry and a high frequency pressure transducer. The measurement results indicate that a tip leakage vortex is produced very close to the leading edge, and becomes the strongest at about 10% axial chord from the leading edge. Breakdown of the vortex periodically occurs at about 1/3 chord, causing very strong turbulence in the radial direction. Flow separation happens on the tip suction surface at about half chord, prompting the corner vortex migrating toward the pressure side. Tangential migration of the low-energy fluids results in substantial flow blockage and turbulence in the rear of a rotor passage. Unsteady interactions among the tip leakage vortex, the separated vortex and the corner flow should contribute to the inception of the rotating stall in a compressor.

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Numerical Study of Vortices and Their Interactions in the Passage of Rotor Blade With Tip Gap

Volume 1: Compressors, Fans, and Pumps; Turbines; Heat Transfer; Structures and Dynamics ◽

10.1115/gtindia2019-2733 ◽

2019 ◽

Author(s):

Sachin Singh Rawat ◽

B. V. S. S. S. Prasad

Keyword(s):

Turbulence Model ◽

Numerical Study ◽

Flow Direction ◽

Three Dimensional ◽

Suction Side ◽

Leakage Flow ◽

Angle Distribution ◽

Tip Leakage Flow ◽

Tip Leakage Vortex ◽

Tip Leakage

Abstract A detailed three-dimensional steady-state numerical investigation using ANSYS CFX-18.2 on a high-pressure turbine blade with linear cascade is done for tip leakage flow of an axial gas turbine. Stationary casing with a fixed blade having tip gap is considered for the present study. There is leakage flow from the pressure side to the suction side of the blade which consecutively rolls up in the passage and forms the tip leakage vortex. The formation of vortices and their interaction with each other inside the passage is complex which makes experimental investigation difficult. The effect of tip gap size, off-design incidence angles, outlet Mach number, pitch size and flow path (stagger angle) are several parameters considered during the present study. The strength of tip leakage vortex and the vortex formed inside the gap is maximum. The losses are compared in terms of total pressure loss coefficient. The deviation of the flow direction is measured in terms of yaw angle distribution. Among various turbulence model available in CFX 18.2 the BSL k-ω turbulence model shows the most reliable results with experimental data. The results are compared with the base model without the tip gap. This investigation incites a better design of the blade tip with a precise reduction in losses.

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Measurement of the Three-Dimensional Tip Region Flow Field in an Axial Compressor

Journal of Turbomachinery ◽

10.1115/1.2929275 ◽

1993 ◽

Vol 115 (3) ◽

pp. 468-476 ◽

Cited By ~ 33

Author(s):

R. C. Stauter

Keyword(s):

Flow Field ◽

Three Dimensional ◽

Axial Compressor ◽

Time Resolved ◽

Tip Leakage Vortex ◽

Tip Leakage ◽

Rotating Blade ◽

Flow Phenomena ◽

Component Velocity ◽

And Behavior

A two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a two-stage axial compressor model. The system has been used to make time-resolved measurements both between compressor blade rows and within the rotating blade passages in an axial compressor. The data show the nature and behavior of the complex, three-dimensional flow phenomena present in the tip region of a compressor as they convect downstream. In particular, the nature of the tip leakage vortex is apparent, being manifested by high blockage as well as the expected vortical motion. The data indicate that the radial flows associated with the tip leakage vortex begin to decrease while within the rotor passage, and that they temporarily increase aft of the passage.

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