Numerical Simulation of the Shock-Tip Leakage Vortex Interaction in a HPC Front Stage

1999 ◽  
Vol 121 (3) ◽  
pp. 456-468 ◽  
Author(s):  
M. Hoeger ◽  
G. Fritsch ◽  
D. Bauer
Keyword(s):  
Three Dimensional ◽  
Leading Edge ◽  
Navier Stokes ◽  
Stream Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Blade Tip ◽  
Operating Points ◽  
Insight Into

For a single-stage transonic compressor rig at the TU Darmstadt, three-dimensional viscous simulations are compared to L2F measurements and data from the EGV leading edge instrumentation to demonstrate the predictive capability of the Navier–Stokes code TRACE_S. In a second step the separated regions at the blade tip are investigated in detail to gain insight into the mechanisms of tip leakage vortex-shock interaction at operating points close to stall, peak efficiency, and choke. At the casing the simulations reveal a region with axially reversed flow, leading to a rotationally asymmetric displacement of the outermost stream surface and a localized additional pitch-averaged blockage of approximately 2 percent. Loss mechanisms and streamline patterns deduced from the simulation are also discussed. Although the flow is essentially three-dimensional, a simple model for local blockage from tip leakage is demonstrated to significantly improve two-dimensional simulations on S1-surfaces.

scholarly journals Numerical Simulation of the Shock-Tip Leakage Vortex Interaction in a HPC Front Stage

1998 ◽  
Author(s):  
M. Hoeger ◽  
G. Fritsch ◽  
D. Bauer
Keyword(s):  
Leading Edge ◽  
Navier Stokes ◽  
Predictive Capability ◽  
Stream Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Blade Tip ◽  
Operating Points ◽  
Insight Into

For a single-stage transonic compressor rig at the TU Darmstadt 3D viscous simulations are compared to L2F-measurements and data from the EGV leading edge instrumentation to demonstrate the predictive capability of the Navier-Stokes code TRACE_S. In a second step the separated regions at the blade tip are investigated in detail to gain insight into the mechanisms of tip leakage vortex-shock interaction at operating points close to stall, peak efficiency and choke. At the casing the simulations reveal a region with axially reversed flow, leading to a rotationally asymmetric displacement of the outermost stream surface and a localized additional pitch-average blockage of app. 2%. Loss mechanisms and streamline patterns deduced from the simulation are also discussed. Although the flow is essentially 3D, a simple model for local blockage from tip leakage is demonstrated to significantly improve 2D-simulations on S1-surfaces.

Flow Field Unsteadiness in the Tip Region of a Transonic Compressor Rotor

1997 ◽  
Vol 119 (1) ◽  
pp. 122-128 ◽  
Author(s):  
S. L. Puterbaugh ◽  
W. W. Copenhaver
Keyword(s):  
Flow Field ◽  
High Performance ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Vortex Interaction ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Operating Points

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.

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

2018 ◽  
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.

Three-Dimensional Navier-Stokes Analysis of Turbine Rotor and Tip-Leakage Flowfield

1997 ◽  
Author(s):  
J. Luo ◽  
B. Lakshminarayana
Keyword(s):  
Three Dimensional ◽  
Turbine Rotor ◽  
Secondary Flows ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Leakage Flow ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Blade Tip

The 3-D viscous flowfield in the rotor passage of a single-stage turbine, including the tip-leakage flow, is computed using a Navier-Stokes procedure. A grid-generation code has been developed to obtain embedded H grids inside the rotor tip gap. The blade tip geometry is accurately modeled without any “pinching”. Chien’s low-Reynolds-number k-ε model is employed for turbulence closure. Both the mean-flow and turbulence transport equations are integrated in time using a four-stage Runge-Kutta scheme. The computational results for the entire turbine rotor flow, particularly the tip-leakage flow and the secondary flows, are interpreted and compared with available data. The predictions for major features of the flowfield are found to be in good agreement with the data. Complicated interactions between the tip-clearance flows and the secondary flows are examined in detail. The effects of endwall rotation on the development and interaction of secondary and tip-leakage vortices are also analyzed.

Numerical investigations on tip leakage flow characteristics and vortex trajectory prediction model in centrifugal compressor

2016 ◽  
Vol 230 (8) ◽  
pp. 757-772 ◽  
Author(s):  
Huijing Zhao ◽  
Zhiheng Wang ◽  
Shubo Ye ◽  
Guang Xi
Keyword(s):  
Prediction Model ◽  
Flow Instability ◽  
Leading Edge ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Blade Tip

To better understand the characteristics of tip leakage flow and interpret the correlation between flow instability and tip leakage flow, the flow in the tip region of a centrifugal impeller is investigated by using the Reynolds averaged Navier–Stokes solver technique. With the decrease of mass flow rate, both the tip leakage vortex trajectory and the mainflow/tip leakage flow interface are shifted towards upstream. The mainflow/tip leakage flow interface finally reaches the leading edge of main blade at the near-stall condition. A prediction model is proposed to track the tip leakage vortex trajectory. The blade loading at blade tip and the averaged streamwise velocity of main flow within tip clearance height are adopted to determine the tip leakage vortex trajectory in the proposed model. The coefficient k in Chen’s model is found to be not a constant. Actually, it is correlated with h/b (the ratio of blade tip clearance height to blade tip thickness), because h/b will significantly influence the flow structure across the tip clearance. The effectiveness of the proposed prediction model is further demonstrated by tracking the tip leakage vortex trajectories in another three centrifugal impellers characterized with different h/b (s).

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

1993 ◽  
Vol 115 (3) ◽  
pp. 435-443 ◽  
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.

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

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.

Study of Shock/Blade Tip Leakage Vortex/Boundary Layer Interaction in a Transonic Rotor With IDDES Method

2013 ◽  
Author(s):  
Ke Shi ◽  
Song Fu
Keyword(s):  
Boundary Layer ◽  
Shock Wave ◽  
Vortex Breakdown ◽  
Leading Edge ◽  
Wave Surface ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Layer Interaction ◽  
Boundary Layer Interaction ◽  
Blade Tip

In the present study, Improved Delayed Detached Eddy Simulation (IDDES) based on k-ω-SST turbulence model is applied to study the unsteady phenomenon in a transonic compressor rotor. Particular emphasis is on the understanding of the complex underlying mechanisms for the flow unsteadiness caused by the interaction of passage shock, blade tip leakage vortex (BTLV) and the blade boundary layer. The sources of the significant unsteadiness of the flow are shown. At the lower span height, where the BTLV is far away, the shock wave ahead of the blade leading edge impinges on the suction surface boundary layer of the adjacent blade, causing the shock wave/boundary layer interaction (SWBLI). Boundary layer thickness grows, while flow separates after the interaction. Predicted by IDDES calculation, this shock-induced separation exists as a separation bubble. The flow reattaches very soon after separation. At the near tip region, the shock wave surface deforms due to the strong interaction between the shock and the BTLV. Oscillation of the shock wave surface near the vortex core infers an unsteady contend between the shock and the vortex. Iso-surfaces of the Q parameter are applied to identify the vortex and its structure. Normally, the vortex breakdown in the rotor passage will lead to stall. However, in the present transonic case, the vortex breakdown was observed even at the near peak efficiency point. While the mass flow rate decreases, the shock waves formed ahead of the rotor blade leading edge were pushed upstream, causing earlier casing wall boundary layer separation. Upstream moving behavior of the shock is considered a new stall process.

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.

Unsteady Three-Dimensional Flow Phenomena Due to Breakdown of Tip Leakage Vortex in a Transonic Axial Compressor Rotor

2004 ◽  
Author(s):  
K. Yamada ◽  
M. Furukawa ◽  
T. Nakano ◽  
M. Inoue ◽  
K. Funazaki
Keyword(s):  
Shock Wave ◽  
Flow Field ◽  
Vortex Breakdown ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Leading Edge ◽  
Tip Leakage Flow ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Compressor Rotor

Unsteady three-dimensional flow fields in a transonic axial compressor rotor (NASA Rotor 37) have been investigated by unsteady Reynolds-averaged Navier-Stokes simulations. The simulations show that the breakdown of the tip leakage vortex occurs in the compressor rotor because of the interaction of the vortex with the shock wave. At near-peak efficiency condition small bubble-type breakdown of the tip leakage vortex happens periodically and causes the loading of the adjacent blade to fluctuate periodically near the leading edge. Since the blade loading near the leading edge is closely linked to the swirl intensity of the tip leakage vortex, the periodic fluctuation of the blade loading leads to the periodic breakdown of the tip leakage vortex, resulting in self-sustained flow oscillation in the tip leakage flow field. However, the tip leakage vortex breakdown is so weak and small that it is not observed in the time-averaged flow field at near-peak efficiency condition. On the other hand, spiral-type breakdown of the tip leakage vortex is caused by the interaction between the vortex and the shock wave at near-stall operating condition. The vortex breakdown is found continuously since the swirl intensity of tip leakage vortex keeps strong at near-stall condition. The spiral-type vortex breakdown has the nature of self-sustained flow oscillation and gives rise to the large fluctuation of the tip leakage flow field, in terms of shock wave location, blockage near the rotor tip and three-dimensional separation structure on the suction surface. It is found that the breakdown of the tip leakage vortex leads to the unsteady flow phenomena near the rotor tip, accompanying large blockage effect in the transonic compressor rotor at the near-stall condition.

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