Detached-eddy simulation with compressibility corrections applied to a supersonic axisymmetric base flow

Forsythe, James R.; Hoffmann, Klaus A.; Squires, Kyle D.

doi:10.2514/6.2002-586

Cited by 39 publications

(23 citation statements)

References 23 publications

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“…However, the experimental nature of their work prevent them from directly acquiring unsteady data in the separated flow field, thus limiting our comprehension of such flows. During the last ten years, several works have been devoted to the simulation of such a flow in order to improve turbulence model predictions or to validate new hybrid numerical approaches (see for example, Fureby, Nilsson & Andersson 1999;Forsythe et al 2002;Baurle et al 2003;Kawai & Fujii 2005). Unfortunately, these numerical studies have focused on time-averaged results and none of them has been used to assess the unsteadiness of the flow, except the study of Sandberg & Fasel (2006a, b) who investigated the transitional wake at Re D = 100 000 with D the diameter of the trailing edge, with the use of DNS and linear stability investigations.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of the compressible mixing layer past an axisymmetric trailing edge

et al. 2007

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Numerical simulation of a compressible mixing layer past an axisymmetric trailing edge is carried out for a Reynolds number based on the diameter of the trailing edge approximately equal to 2.9 × 106. The free-stream Mach number at separation is equal to 2.46, which corresponds to experiments and leads to high levels of compressibility. The present work focuses on the evolution of the turbulence field through extra strain rates and on the unsteady features of the annular shear layer. Both time-averaged and instantaneous data are used to obtain further insight into the dynamics of the flow. An investigation of the time-averaged flow field reveals an important shear-layer growth rate in its initial stage and a strong anisotropy of the turbulent field. The convection velocity of the vortices is found to be somewhat higher than the estimated isentropic value. This corroborates findings on the domination of the supersonic mode in planar supersonic/subsonic mixing layers. The development of the shear layer leads to a rapid decrease of the anisotropy until the onset of streamline realignment with the axis. Due to the increase of the axisymmetric constraints, an adverse pressure gradient originates from the change in streamline curvature. This recompression is found to slow down the eddy convection. The foot shock pattern features several convected shocks emanating from the upper side of the vortices, which merge into a recompression shock in the free stream. Then, the flow accelerates and the compressibility levels quickly drop in the turbulent developing wake. Some evidence of the existence of large-scale structures in the near wake is found through the domination of the azimuthal mode m = 1 for a Strouhal number based on trailing-edge diameter equal to 0.26.

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Section: Introductionmentioning

confidence: 99%

Numerical simulation of the compressible mixing layer past an axisymmetric trailing edge

et al. 2007

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“…In this region, there is a large 'hump' with the time-averaged Cp showing the best agreement with the flight test. This discrepancy has been observed in other fighter aircraft simulations and is typically due to the inability of the RANS turbulence models to accurately capture the effect of the massive separation and strong unsteady vortices [12,14,15,44,45]. …”

Section: F-16xlmentioning

confidence: 86%

“…CFD has its own limitations, of course, such as turbulence and transition modelling, to name a few. However, the large body of previous work [12][13][14][15][16][17][18] performed by researchers at the US Air Force Academy using the unstructured mesh solver Cobalt [19] coupled with a detached-eddy simulation (DES) turbulence treatment, adaptive mesh refinement, six degree of freedom (6 DOF) motion, and deforming grids for aero-elasticity has led to a high-fidelity capability for computing stability and control characteristics.…”

Section: Introductionmentioning

confidence: 99%

Comparisons of computational fluid dynamics solutions of static and manoeuvring fighter aircraft with flight test data

McDaniel

Cummings

Bergeron

et al. 2009

Proceedings of the Institution of Mechanical Engineers, Part G:

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As the capabilities of computational fluid dynamics (CFD) to model full aircraft configurations improve, and the speeds of massively parallel machines increase, it is expected that CFD simulations will be used more and more to steer or in some cases even replace traditional flight test analyses. The mission of the US Air Force SEEK EAGLE office is to clear any new weapon configurations and loadings for operational use. As more complex weapons are developed and highly asymmetric loadings are requested, the SEEK EAGLE office is tasked with providing operational clearances for literally thousands of different flight configurations. High-fidelity CFD simulations employing the turbulent Navier-Stokes equations are in a prime position to help reduce some of the required wind-tunnel and/or flight test workload. However, these types of CFD simulations are still too time consuming to populate a full stability and control parameter database in a bruteforce manner. This article reviews results previously published by the authors, which validate the ability of high-fidelity CFD techniques to compute static force and moment characteristics of aircraft configurations. A methodology to generate efficient but non-linear reduced-order aerodynamic loads models from dynamic CFD solutions, which in-turn may be used to quickly analyse various stability and control characteristics at a particular flight condition, is introduced, and the results based on the US Air Force F-16C fighter aircraft that exemplify the process are discussed.

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“…The RANS models are widely used in industrial applications since they require relatively small computational resources due to the ensemble-averaging of the governing equations. While the RANS method models model all the turbulence scales, which often fail to provide accurate results for complex flows since the large turbulence scales for separated flows are strongly dependent on the geometry [14] .…”

Section: Turbulence Modelmentioning

confidence: 99%

Analysis of the pump-turbine S characteristics using the detached eddy simulation method

Sun

Xiao

Wang

et al. 2014

Chin. J. Mech. Eng.

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Current research on pump-turbine units is focused on the unstable operation at off-design conditions, with the characteristic curves in generating mode being S-shaped. Unlike in the traditional water turbines, pump-turbine operation along the S-shaped curve can lead to difficulties during load rejection with unusual increases in the water pressure, which leads to machine vibrations. This paper describes both model tests and numerical simulations. A reduced scale model of a low specific speed pump-turbine was used for the performance tests, with comparisons to computational fluid dynamics(CFD) results. Predictions using the detached eddy simulation(DES) turbulence model, which is a combined Reynolds averaged Naviers-Stokes(RANS) and large eddy simulation(LES) model, are compared with the two-equation turbulence mode results. The external characteristics as well as the internal flow are for various guide vane openings to understand the unsteady flow along the so called S characteristics of a pump-turbine. Comparison of the experimental data with the CFD results for various conditions and times shows that DES model gives better agreement with experimental data than the two-equation turbulence model. For low flow conditions, the centrifugal forces and the large incident angle create large vortices between the guide vanes and the runner inlet in the runner passage, which is the main factor leading to the S-shaped characteristics. The turbulence model used here gives more accurate simulations of the internal flow characteristics of the pump-turbine and a more detailed force analysis which shows the mechanisms controlling of the S characteristics.

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Detached-eddy simulation with compressibility corrections applied to a supersonic axisymmetric base flow

Cited by 39 publications

References 23 publications

Numerical simulation of the compressible mixing layer past an axisymmetric trailing edge

Numerical simulation of the compressible mixing layer past an axisymmetric trailing edge

Comparisons of computational fluid dynamics solutions of static and manoeuvring fighter aircraft with flight test data

Analysis of the pump-turbine S characteristics using the detached eddy simulation method

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