scholarly journals Detached-Eddy Simulation of the vortical flow field about the VFE-2 delta wing

2013 ◽  
Vol 24 (1) ◽  
pp. 66-76 ◽  
Author(s):  
Russell M. Cummings ◽  
Andreas Schütte
Keyword(s):  
Flow Field ◽  
Delta Wing ◽  
Vortical Flow ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

Detached Eddy Simulation of Unsteady Flow Field and Prediction of Aerodynamic Sound in a Half-Ducted Propeller Fan

2011 ◽  
Author(s):  
K. Kusano ◽  
J. H. Jeong ◽  
K. Yamada ◽  
M. Furukawa
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Tip Vortex ◽  
Vortical Flow ◽  
Detached Eddy Simulation ◽  
Acoustic Analogy ◽  
Aerodynamic Sound ◽  
Pressure Surface ◽  
Eddy Simulation ◽  
Ducted Propeller

Three-dimensional structures and unsteady nature of vortical flow fields in a half ducted propeller fan have been investigated by a detached eddy simulation (DES) based on k-ω two-equation turbulence model. The validity of the numerical simulation performed in the present study was demonstrated by the comparison to LDV measurement results. The simulation shows the tip vortex is so strong that it dominates the flow field near the rotor tip. The tip vortex does not impinge on the pressure surface of the adjacent blade directly, however it interacts with the shroud surface and induces a separation vortex on the shroud. Furthermore, this separation vortex interacts with the pressure surface of the adjacent blade. These flow structures cause high pressure fluctuation on the shroud surface and the blade pressure surface. Besides, sound pressure levels were predicted by Ffowcs William-Hawkings equation based on Lighthill’s acoustic analogy using the unsteady surface pressure data obtained by DES. As a result, the degree of contribution by each flow structure to overall sound has been estimated quantitatively.

Detached Eddy Simulation of Complex Separation Flows Over a Modern Fighter Model at High Angle of Attack

2017 ◽  
Vol 22 (5) ◽  
pp. 1309-1332 ◽  
Author(s):  
Yang Zhang ◽  
Laiping Zhang ◽  
Xin He ◽  
Xiaogang Deng ◽  
Haisheng Sun
Keyword(s):  
Flow Field ◽  
Angle Of Attack ◽  
Vortical Flow ◽  
Leeward Side ◽  
Detached Eddy Simulation ◽  
High Angle ◽  
Flow Topology ◽  
High Angle Of Attack ◽  
Eddy Simulation ◽  
Separation Flows

AbstractThis paper presents the simulation of complex separation flows over a modern fighter model at high angle of attack by using an unstructured/hybrid grid based Detached Eddy Simulation (DES) solver with an adaptive dissipation second-order hybrid scheme. Simulation results, including the complex vortex structures, as well as vortex breakdown phenomenon and the overall aerodynamic performance, are analyzed and compared with experimental data and unsteady Reynolds-Averaged Navier-Stokes (URANS) results, which indicates that with the DES solver, clearer vortical flow structures are captured and more accurate aerodynamic coefficients are obtained. The unsteady properties of DES flow field are investigated in detail by correlation coefficient analysis, power spectral density (PSD) analysis and proper orthogonal decomposition (POD) analysis, which indicates that the spiral motion of the primary vortex on the leeward side of the aircraft model is highly nonlinear and dominates the flow field. Through the comparisons of flow topology and pressure distributions with URANS results, the reason why higher and more accurate lift can be obtained by DES is discussed. Overall, these results show the potential capability of present DES solver in industrial applications.

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.

Analysis of Delta-Wing Vortical Substructures Using Detached-Eddy Simulation

AIAA Journal ◽  
10.2514/1.755 ◽  
2006 ◽  
Vol 44 (5) ◽  
pp. 964-972 ◽  
Author(s):  
Anthony M. Mitchell ◽  
Scott A. Morton ◽  
James R. Forsythe ◽  
Russell M. Cummings
Keyword(s):  
Delta Wing ◽  
Detached Eddy Simulation ◽  
Eddy Simulation

Detached-Eddy Simulations and Reynolds-Averaged Navier-Stokes Simulations of Delta Wing Vortical Flowfields

2002 ◽  
Vol 124 (4) ◽  
pp. 924-932 ◽  
Author(s):  
Scott Morton ◽  
James Forsythe ◽  
Anthony Mitchell ◽  
David Hajek
Keyword(s):  
Vortex Breakdown ◽  
Delta Wing ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Fighter Aircraft ◽  
Eddy Simulation ◽  
Reynolds Averaged Navier Stokes ◽  
High Reynolds

An understanding of vortical structures and vortex breakdown is essential for the development of highly maneuverable vehicles and high angle of attack flight. This is primarily due to the physical limits these phenomena impose on aircraft and missiles at extreme flight conditions. Demands for more maneuverable air vehicles have pushed the limits of current CFD methods in the high Reynolds number regime. Simulation methods must be able to accurately describe the unsteady, vortical flowfields associated with fighter aircraft at Reynolds numbers more representative of full-scale vehicles. It is the goal of this paper to demonstrate the ability of detached-eddy Simulation (DES), a hybrid Reynolds-averaged Navier-Stokes (RANS)/large-eddy Simulation (LES) method, to accurately predict vortex breakdown at Reynolds numbers above 1×106. Detailed experiments performed at Onera are used to compare simulations utilizing both RANS and DES turbulence models.

scholarly journals Comparative Study on CFD Turbulence Models for the Flow Field in Air Cooled Radiator

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1687
Author(s):  
Chao Yu ◽  
Xiangyao Xue ◽  
Kui Shi ◽  
Mingzhen Shao ◽  
Yang Liu
Keyword(s):  
Flow Field ◽  
Transient Flow ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Compartment Model ◽  
Navier Stokes ◽  
Engine Compartment ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Relevant Calculation

This paper compares the performances of three Computational Fluid Dynamics (CFD) turbulence models, Reynolds Average Navier-Stokes (RANS), Detached Eddy Simulation (DES), and Large Eddy Simulation (LES), for simulating the flow field of a wheel loader engine compartment. The distributions of pressure fields, velocity fields, and vortex structures in a hybrid-grided engine compartment model are analyzed. The result reveals that the LES and DES can capture the detachment and breakage of the trailing edge more abundantly and meticulously than RANS. Additionally, by comparing the relevant calculation time, the feasibility of the DES model is proved to simulate the three-dimensional unsteady flow of engine compartment efficiently and accurately. This paper aims to provide a guiding idea for simulating the transient flow field in the engine compartment, which could serve as a theoretical basis for optimizing and improving the layout of the components of the engine compartment.

scholarly journals Assessing the Capability of Doppler Global Velocimetry to Measure Vortical Flow Fields

1994 ◽  
Vol 208 (2) ◽  
pp. 99-105
Author(s):  
J F Meyers ◽  
L Scott Miller
Keyword(s):  
Flow Field ◽  
Delta Wing ◽  
Video Camera ◽  
Temporal Information ◽  
Vortical Flow ◽  
Velocity Measurements ◽  
Flow Diagnostics ◽  
Measurement Plane ◽  
Component Velocity ◽  
Velocity Images

A new non-intrusive flow diagnostics instrumentation system, Doppler global velocimetry, is presented. The system is capable of making simultaneous three-component velocity measurements within a selected measurement plane at video camera rates. These velocity images can provide the researcher with spatial and temporal information about the flow field in a global sense. The investigation of a vortical flow above a 75° delta wing comparing standard three-component fringe-type laser velocimetry measurements with Doppler global velocimetry measurements is presented.

Detached Eddy Simulation: Recent Development and Application to Compressor Tip Leakage Flow

2021 ◽  
pp. 1-400
Author(s):  
Xiao He ◽  
Fanzhou Zhao ◽  
Mehdi Vahdati
Keyword(s):  
Flow Field ◽  
Model Development ◽  
Main Flow ◽  
Transition To Turbulence ◽  
Leakage Flow ◽  
Detached Eddy Simulation ◽  
Grid Spacing ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Eddy Simulation

Abstract Detached Eddy Simulation (DES) and its variants are emerging tools for turbomachinery simulations. In this paper, the state-of-the-art upgrades of DES are reviewed, and their capabilities in predicting compressor tip leakage flow are discussed. The upgrade with the best potential is identified as the Delayed DES (DDES) method with the grid spacing FKHΔhyb, which unlocks the physics of the Kelvin-Helmholtz instability in compressor tip leakage flow. The upgraded grid spacing FKHΔhyb is compared against the widely used default one Δmax in a backward-facing step and a low-speed axial compressor rotor. Results show that the DDES method with FKHΔhyb predicts both the main flow field and the turbulence field with reasonably good accuracy. However, the original DDES method with Δmax predicts a delayed transition to turbulence, which leads to an inaccurate prediction of the main flow field when using a coarse mesh. The findings in this paper highlight the future opportunities for using the DDES-FKHΔhyb method to predict tip-driven compressor stall and generate a turbulence database for turbulence model development.

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