Numerical Investigation of Intermittent Corner Separation in a Linear Compressor Cascade

2016 ◽  
Author(s):  
Wei Ma ◽  
Feng Gao ◽  
Xavier Ottavy ◽  
Lipeng Lu ◽  
A. J. Wang
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Leading Edge ◽  
Suction Side ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Corner Separation ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

Recently bimodal phenomenon in corner separation has been found by Ma et al. (Experiments in Fluids, 2013, doi:10.1007/s00348-013-1546-y). Through detailed and accurate experimental results of the velocity flow field in a linear compressor cascade, they discovered two aperiodic modes exist in the corner separation of the compressor cascade. This phenomenon reflects the flow in corner separation is high intermittent, and large-scale coherent structures corresponding to two modes exist in the flow field of corner separation. However the generation mechanism of the bimodal phenomenon in corner separation is still unclear and thus needs to be studied further. In order to obtain instantaneous flow field with different unsteadiness and thus to analyse the mechanisms of bimodal phenomenon in corner separation, in this paper detached-eddy simulation (DES) is used to simulate the flow field in the linear compressor cascade where bimodal phenomenon has been found in previous experiment. DES in this paper successfully captures the bimodal phenomenon in the linear compressor cascade found in experiment, including the locations of bimodal points and the development of bimodal points along a line that normal to the blade suction side. We infer that the bimodal phenomenon in the corner separation is induced by the strong interaction between the following two facts. The first is the unsteady upstream flow nearby the leading edge whose angle and magnitude fluctuate simultaneously and significantly. The second is the high unsteady separation in the corner region.

Detached Eddy Simulation of Transition in Turbomachinery: Linear Compressor Cascade

2021 ◽  
pp. 1-10
Author(s):  
Zifei Yin ◽  
Paul Durbin
Keyword(s):  
Boundary Layer ◽  
Large Scale ◽  
Separated Flow ◽  
Adaptive Model ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Linear Compressor Cascade

Abstract The adaptive, l2-omega delayed detached eddy simulation model was selected to simulate the flow in the V103 linear compressor cascade. The Reynolds number based on axial chord length is 138,500. Varies inflow turbulent intensities from 0% to 10% were tested to evaluate the performance of the adaptive model. The adaptive model is capable of capturing the laminar boundary layer and the large scale perturbations inside it. The instability of large scale disturbances signals the switch to a hybrid simulation of turbulent boundary layer -- the transition front is thus predicted. In the case of separation-induced transition, the adaptive model, which uses eddy simulation in separated flow, can predict the separation bubble size accurately. Generally, the adaptive, delayed detached eddy simulation model can simulate the transitional separated flow in a linear compressor cascade, with a correct response to varying turbulent intensities.

Hybrid RANS/LES Simulation of Corner Stall in a Linear Compressor Cascade

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Guoping Xia ◽  
Gorazd Medic ◽  
Thomas J. Praisner
Keyword(s):  
Axial Flow ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Special Treatment ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Data Set ◽  
Linear Compressor ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

Current design-cycle Reynolds-averaged Navier–Stokes (RANS) based computational fluid dynamics (CFD) methods have the tendency to over-predict corner-stall events for axial-flow compressors operating at off-design conditions. This shortcoming has been demonstrated even in simple single-row cascade configurations. Here we report on the application of hybrid RANS/large eddy simulation (LES), or detached eddy simulation (DES), for simulating the corner-stall data from the linear compressor cascade work conducted at Ecole Centrale de Lyon. This benchmark data set provides detailed loss information while also revealing a bimodal behavior of the separation which, not surprisingly, is also not well modeled by RANS. The hybrid RANS/LES results presented here predict bimodal behavior similar to the data only when special treatment is adopted to resolve the leading-edge endwall region where the horseshoe vortex (HV) forms. The (HV) is shown to be unstable, which produces the bimodal instability. The DES simulation without special treatment or refinement in the HV region fails to predict the bimodal instability, and thus the bimodal behavior of the separation. This, in turn, causes a gross over-prediction in the scale of the corner-stall. The HV region is found to be unstable with rolling of the tertiary vortex (TV) over the secondary vortex and merging with the primary HV. With these flow dynamics realized in the DES simulations, the corner stall characteristics are found to be in better agreement with the experimental data, as compared to RANS and standard DES approaches.

Unsteady Pressure Investigations of Corner Separated Flow in a Linear Compressor Cascade

2015 ◽  
Author(s):  
Gherardo Zambonini ◽  
Xavier Ottavy
Keyword(s):  
Transfer Functions ◽  
Leading Edge ◽  
Positive Pressure ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Linear Compressor ◽  
Corner Separation ◽  
Unsteady Pressure ◽  
Linear Compressor Cascade ◽  
End Wall

The aim of this work is to present detailed unsteady pressure measurements of three-dimensional flow field in a NACA 65 linear compressor cascade. Chord-based Reynolds number of 382000 and incidence angle of 4 degrees were chosen as target configuration of the rig, which clearly presents the corner separation phenomenon at the juncture of the blade suction side and the end-wall. Concerning the experiments, a characterization of the mean and fluctuating component of wall static pressure on the surface of a specially developed blade is achieved at first. This fluctuating component is investigated utilizing nineteen high sensitivity condenser microphones plugged into blade cavities which have been carefully calibrated. Transfer functions obtained by calibration are exploited to reconstruct the time-dependent pressure signal and finally statistics, conditional ensemble averages, coherence and spectra analyses of fluctuations are presented in order to investigate the unsteady characteristics of the corner separation. High values of root mean square are individuated near the leading edge and in the separation region on the suction surface of the blade. Skewness and kurtosis show an intermittent behavior of the separation onset, which moves upstream and downstream on the suction surface. This intermittency of the separation line is probably linked with the existence of a bimodal behavior of the size of the corner separation. The analyses of coherence and conditional ensemble average between the signals at the leading edge and at the onset of the separation suggest a critical influence of angle and velocity of the incoming end-wall boundary layer on the positive pressure signatures of the shear layer, which characterize the inception of the separation.

scholarly journals Large-eddy simulation of 3-D corner separation in a linear compressor cascade

2015 ◽  
Vol 27 (8) ◽  
pp. 085105 ◽  
Author(s):  
Feng Gao ◽  
Wei Ma ◽  
Gherardo Zambonini ◽  
Jérôme Boudet ◽  
Xavier Ottavy ◽  
...  
Keyword(s):  
Large Eddy Simulation ◽  
Compressor Cascade ◽  
Linear Compressor ◽  
Corner Separation ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Linear Compressor Cascade

Adaptive Detached Eddy Simulation of End-Wall Flow in a Linear Compressor Cascade

2020 ◽  
Author(s):  
Zifei Yin
Keyword(s):  
Pressure Coefficient ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Local Flow ◽  
Linear Compressor ◽  
Eddy Simulation ◽  
Wall Flow ◽  
Linear Compressor Cascade ◽  
End Wall ◽  
Des Model

Abstract Delayed detached eddy simulations and wall-modeled eddy simulations using the adaptive DES model were performed to simulate corner separation in the Ecole Centrale de Lyon linear compressor cascade. The adaptive DES model directly uses length scale to define eddy viscosity, which makes it nature to compute the model constant CDES dynamically. The dynamic procedure adapts viscosity to local flow and grid. Delayed detached eddy simulations, with and without the dynamic procedure, were performed to demonstrate the benefit of adapting viscosity to local flow. Recycling method was adopted to generate inflow unsteady turbulent boundary layer for wall-modeled eddy simulations. The wall-modeled eddy simulation showed improvement over delayed-DES, in terms of static pressure coefficient around the blade and total pressure loss at downstream locations.

An Integrated Particle-Tracking Impact/Adhesion Model for the Prediction of Fouling in a Subsonic Compressor

2012 ◽  
Vol 134 (9) ◽  
Author(s):  
D. Borello ◽  
F. Rispoli ◽  
P. Venturini
Keyword(s):  
Leading Edge ◽  
Suction Side ◽  
Navier Stokes ◽  
Compressor Cascade ◽  
Deposit Formation ◽  
Stagnation Region ◽  
Vortical Structures ◽  
Tip Leakage ◽  
Eddy Simulation ◽  
Linear Compressor Cascade

The present paper reports on the analysis of the motion of adhesive particles and deposit formation in a 3D linear compressor cascade in order to investigate the fouling in turbomachinery flows. The unsteady flow field is provided by a prior hybrid large-eddy simulation (LES)/Reynolds-averaged Navier-Stokes (RANS) computation. The particles are individually tracked and the deposit formation is evaluated on the basis of the well-established Thornton and Ning model. Although the study is limited to three regions of the blade, where the most relevant turbulent phenomena occurs, the prediction of fouling shows good agreement with real situations. Deposits form near the casing and the hub, in the zones where there are strong vortical structures originated by the tip leakage and hub vortices. On the blade, the deposit analysis is focused on three main regions: (a) along the stagnation region on the leading edge; (b) on the suction side, where the particles are conveyed by the hub vortex towards blade surfaces; and (c) on the pressure side, where a clean zone forms between leading edge and the blade surface, as can be seen in real compressors.

Investigation of Corner Separation in a Linear Compressor Cascade Using DDES

2015 ◽  
Author(s):  
Yangwei Liu ◽  
Hao Yan ◽  
Lipeng Lu
Keyword(s):  
Flow Field ◽  
Eddy Viscosity ◽  
Three Dimension ◽  
Separation Region ◽  
Detached Eddy Simulation ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Simple Modification ◽  
Corner Separation ◽  
Eddy Simulation

Delayed Detached Eddy Simulation (DDES) method, compared with the RANS method, can more accurately predict the complexity and unsteadiness naturally associated with the compressor flow. DDES method, which incorporates a simple modification into the initial detached eddy simulation (DES) introduces kinematic eddy viscosity into turbulence model to take both effects of grid spacing and eddy-viscosity field into considerations. An attempt is made in the present paper to apply DDES for investigating the flow field in a compressor cascade. Three-dimension (3D) corner separation, which is also referred as corner separation, have been identified as an inherent flow feature of the corner formed by the blade suction surface and endwall of axial compressors. The flow visualization and the quantification of passage blockage expose that corner separation contribute most to the total passage blockage. In order to accurately predict 3D corner separation by employing CFD and increase the performance in compressor routine design by controlling such phenomenon, this paper tries to figure out its mechanism and investigate the turbulence flow field by using DDES method. Numerical simulations are conducted under different incidences in a linear PVD compressor cascade. The results show passage vortex starting at mid-chord position in cascade develops into dominant secondary vortex and obviously enhances corner separation in the PVD cascade. DDES method, which can capture intensive vortex flow and predict complicated flow at the separation region, also illustrates the corner vortex breaks into small stripe vortices which mix with the mainstream flow at the blade trailing edge. The total pressure loss is high in the corner separation region.

Three Dimensional Flow in a Linear Compressor Cascade at Design Conditions

1991 ◽  
Author(s):  
Shun Kang ◽  
Ch. Hirsch
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Leading Edge ◽  
Vortex Sheet ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Three Dimensional Flow ◽  
Linear Compressor ◽  
Dimensional Flow ◽  
Linear Compressor Cascade

Experimental data measured upstream, inside and downstream of a large scale linear compressor cascade with NACA 65-1810 blade profile are presented. The flow is surveyed at 15 traverse planes with 14 (in half span) × 24 (in pitch) points inside a passage, and 14 × 33 points downstream exit plane. The measurements are obtained with a small size five hole probe, and wall static pressure taps. It is observed that the three dimensional flow inside and behind the cascade is characterized, not only by the conventional aspects, such as leading edge horseshoe vortices, passage vortices, trailing edge vortex sheet and corner vortices, but also by two spiral node points, formed from the three dimensional separation lines, on suction surface, and the resulting concentrated vortices.

Experimental Investigations of Corner Stall in a Linear Compressor Cascade

2011 ◽  
Author(s):  
Wei Ma ◽  
Xavier Ottavy ◽  
Lipeng Lu ◽  
Francis Leboeuf ◽  
Feng Gao
Keyword(s):  
Velocity Field ◽  
Flow Field ◽  
Three Dimensional ◽  
Suction Side ◽  
Experimental Results ◽  
Flow Conditions ◽  
Compressor Cascade ◽  
Inlet Flow ◽  
Linear Compressor ◽  
Linear Compressor Cascade

In order to gain a better knowledge of the mechanisms of corner stall and to calibrate computational-fluid-dynamics (CFD) tools including both Reynolds-averaged Navier-stokes and large eddy simulation, a detailed and accurate experiment of three-dimensional flow field through a linear compressor cascade has been set up. Experimental data were acquired for a Reynolds number of 3.82 × 105 based on blade chord and inlet flow conditions. First, inlet flow conditions were surveyed by hot-wire anemometry in boundary layers. Second, in order to investigate the effects of incidence, measurements then were acquired at five incidences from −2° to 6°. The results included the outlet flow variables of the cascade, measured by a five-hole pressure probe, and static pressures on both blade and endwall surfaces, measured by pressure taps. Third, the flow field details were measured at an incidence angle of 4°. In this configuration the corner stall region was large enough to be investigated, and without two-dimensional (2D) separation at mid-span on the blade suction side near the trailing edge. The velocity field was then measured by 2D Particle Image Velocimetry in cross-sections parallel to the endwall. And the velocity field in the vicinity of the blade suction side was measured with 2D Laser Dropper Anemometry. In order to test the performance of CFD and also to validate the experimental results, a series of numerical simulations were carried out and compared with the experimental results. We thus obtained a set of detailed measurements which constitute an original and complete data base and in good agreement with the published experimental results in literature. These data were also compared with CFD results and showed that the improvements needed in turbulence modeling in order to accurately simulate the three-dimensional separation configuration of corner stall.

Sign in / Sign up

Export Citation Format

Share Document