Computational Investigation of Unsteady Compressible Flow over a Fixed Delta Wing Using Detached Eddy Simulation

Abstract

Unsteady compressible flows over a stationary 60-degree swept delta wing with a sharpleading edge were computationally simulated at different Mach numbers and moderate angles of theattack. An unstructured grid, Spalart-Allmaras Detached Eddy Simulation turbulence model, and adual-time implicit time integration were used. Vortical flow structures associated with various freestreamconditions are displayed and their variations versus time are studied. Variations of flow fieldparameters, such as u velocity component and pressure coefficient with the flow time are demonstratedat several point probes in the flow field. A Power Spectral Density frequency analysis is performed forsuch unsteady behaviours to identify the dominant frequencies which exist in each flow condition. Thefrequency analyses show that low frequencies associated with vortex breakdown oscillation are the mostdominant frequencies in all cases where vortex breakdown occurs. Dominant frequencies associated withhelical mode instability are also present at the probes downstream of breakdown. Dominant frequenciesrelated to the shear layer instabilities were observed for the low subsonic regime.