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.

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.

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.

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).

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.

Numerical Investigation of Stall Mechanism of an Axial Compressor at Three Different Rotating Speeds

2017 ◽  
Author(s):  
HaoGuang Zhang ◽  
Feng Tan ◽  
Kang An ◽  
YanHui Wu ◽  
WuLi Chu
Keyword(s):  
Axial Flow ◽  
Leading Edge ◽  
Complex Flows ◽  
Tip Leakage Vortex ◽  
Rotating Speed ◽  
Tip Leakage ◽  
Blade Tip ◽  
Layer Flow ◽  
Flow Compressor ◽  
Axial Flow Compressors

For some axial flow compressors, the compressor stall is a result of the blade tip blockage caused by the complex flows, which include the boundary layer flow separation (BLFS), tip leakage flow (TLF), and shock wave. Owing to the difference of the design rotating speed and aerodynamic load in the axial flow compressor, these complex flows might exist in isolation or occur at the same time in practical application. Aiming at the stall mechanism in the axial flow compressors, a great deal of experimental and numerical investigations have been carried out at the design rotating speed. However, the investigation for off-design rotating speed in the axial flow compressors is seldom. Therefore, a transonic axial flow compressor rotor, which is NASA Rotor67, was chosen to investigate the stall mechanism at 100%, 80% and 60% design rotating speeds with the help of the numerical method. Moreover, the guiding suggestions for selecting the measures of increasing the transonic axial flow compressors stability are presented for the later investigation. The compared results show that the variation tendency of the experimental total performance lines are finely repeated by the numerical results at the three design rotating speeds. The fundamental flow mechanism of the rotor is obtained by analyzing the flow field in the blade passage in details. With the decrease of the rotor mass flow at the three design rotating speeds, the starting position of the tip leakage vortex (TLV) moves to the blade leading edge gradually, and the tip leakage vortex also deviates to the pressure surface of the adjacent blade. The deviated angle, which is the angle between the trajectory of the tip leakage vortex core and rotor rotating axis, for near stall point (NS) are about three degree, five degree and nine degree than that for near peak efficiency point (NPE) at 100%, 80% and 60% design rotating speeds respectively. The blockage resulted from the interaction between the tip leakage vortex and shock wave is the cause of the rotor stall at 100% and 80% design rotating speeds. Besides, the breakdown of the tip leakage vortex and leading edge spilled flow (LESF) occur at 80% design rotating speed. At 60% design rotating speed, the blockage caused by the leading edge spilled flow resulted from the tip leakage vortex is the main cause of bringing about the compressor stall, and the boundary layer flow separation (BLFS) in a small scope appears at the blade tip suction surface near the trailing edge.

On the Stability of Transonic Compressor With Wet Compression and Blade Tip Water Injection

2012 ◽  
Author(s):  
Mingcong Luo ◽  
Qun Zheng ◽  
Lanxin Sun ◽  
Qingfeng Deng ◽  
Jiyou Chen ◽  
...  
Keyword(s):  
Total Pressure ◽  
Rotor Blade ◽  
Water Injection ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Compressor Performance ◽  
Wet Compression

The rotor blade tip leakage flow and associated formation of the tip leakage vortex and interaction of the tip leakage vortex with the shockwave, particularly in the case of a transonic compressor rotor have significant impact on the compressor performance and its stability. Air injection upstream of the compressor rotor tip has been shown to improve compressor performance and enhance its stability. The air required for rotor blade tip injection is generally taken from the later stages of the compressor thus causing penalty on the gas turbine performance. In this study, effects of water injection at the rotor tip with and without the wet compression on the compressor performance and its stability have been examined. To achieve the stated objectives, the well tested transonic compressor rotor stage, NASA rotor stage 37, has been numerically simulated. The evaluation of results on various performance parameters such as total pressure ratio, inlet flow capacity and adiabatic efficiency combined with contours of total pressure losses, entropy, Mach No., and temperature including limiting streamlines, shows that the blade tip water injection could help in reducing low energy region downstream of the shockwave and strength of the tip leakage vortex with the compressor operating at its rotating stall boundary condition. The extent of reduction depends on the droplet size, injection flow rate and its velocity. Furthermore, results show that combined case of the blade tip water injection and the wet compression could provide better stall margin enhancement than the blade tip water injection case.

The Effects of Wet Compression and Blade Tip Water Injection on the Stability of a Transonic Compressor Rotor

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
Mingcong Luo ◽  
Qun Zheng ◽  
Lanxin Sun ◽  
Qingfeng Deng ◽  
Jiyou Chen ◽  
...  
Keyword(s):  
Total Pressure ◽  
Rotor Blade ◽  
Water Injection ◽  
Tip Leakage Vortex ◽  
Tip Leakage ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Compressor Performance ◽  
Wet Compression

The rotor blade tip leakage flow and associated formation of the tip leakage vortex and interaction of the tip leakage vortex with the shockwave, particularly in the case of a transonic compressor rotor have significant impact on the compressor performance and its stability. Air injection upstream of the compressor rotor tip has been shown to improve compressor performance and enhance its stability. The air required for rotor blade tip injection is generally taken from the later stages of the compressor thus causing penalty on the gas turbine performance. In this study, effects of water injection at the rotor tip with and without the wet compression on the compressor performance and its stability have been examined. To achieve the stated objectives, the well tested transonic compressor rotor stage, NASA rotor stage 37, has been numerically simulated. The evaluation of results on various performance parameters, such as total pressure ratio, inlet flow capacity, and adiabatic efficiency combined with contours of total pressure losses, entropy, Mach number, and temperature including limiting streamlines, shows that the blade tip water injection could help in reducing low energy region downstream of the shockwave and strength of the tip leakage vortex with the compressor operating at its rotating stall boundary condition. The extent of reduction depends on the droplet size, injection flow rate, and its velocity. Furthermore, results show that combined case of the blade tip water injection and the wet compression could provide better stall margin enhancement than the blade tip water injection case.

A Correlation for Tip Leakage Blockage in Compressor Blade Passages

1999 ◽  
Vol 122 (3) ◽  
pp. 426-432 ◽  
Author(s):  
M. Hoeger ◽  
M. Lahmer ◽  
M. Dupslaff ◽  
G. Fritsch
Keyword(s):  
Three Dimensional ◽  
Transition Function ◽  
Compressor Blade ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Predictive Capability ◽  
Tip Leakage ◽  
Novel Technique ◽  
Gap Height ◽  
Insight Into

Three-dimensional multistage Navier–Stokes simulations for compressor components, rigs, and cascades have been analyzed to gain insight into the tip leakage blockage evolution. From pitch-averaged flow quantities the local displacement caused by tip leakage is determined by means of a novel technique. Close to the throat an additional displacement of about 1–4 percent axial chord is observed for unchoked flow conditions. With tip gap height, stagger, and inlet Mach number as governing variables, a correlation for the tip leakage blockage transition function in blade passages is established, which may be used to improve the predictive capability of S1/S2 compressor aerodesign systems. [S0889-504X(00)00903-X]

scholarly journals A Correlation for Tip Leakage Blockage in Compressor Blade Passages

1999 ◽  
Author(s):  
M. Hoeger ◽  
M. Lahmer ◽  
M. Dupslaff ◽  
G. Fritsch
Keyword(s):  
Mach Number ◽  
Transition Function ◽  
Compressor Blade ◽  
Navier Stokes ◽  
Flow Conditions ◽  
Predictive Capability ◽  
Tip Leakage ◽  
Novel Technique ◽  
Gap Height ◽  
Insight Into

3D multistage Navier-Stokes simulations for compressor components, rigs and cascades have been analyzed to gain insight into the tip leakage blockage evolution. From pitch-averaged flow quantities the local displacement caused by tip leakage is determined by means of a novel technique. Close to the throat an additional displacement of about 1–4% axial chord is observed for unchoked flow conditions. With tip gap height, stagger and inlet Mach number as governing variables a correlation for the tip leakage blockage transition function in blade passages is established, which may be used to improve the predictive capability of S1/S2 compressor aerodesign systems.

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.

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