ANSYS Fluent Methodology for Modelling Hypersonic Flow over an Aerospike

Amy Sturrock

Abstract


Hypersonic flow over an aerospike is inherently unstable, and while aerospikes provide a method of decreasing nose heating and drag, they cause oscillations that would produce adverse moments along the surface of a hypersonic vehicle. The aim of this project was to identify a method for computing these oscillations using ANSYS Fluent and then to identify the frequency of oscillations across a range of aerospike geometries. The hypersonic free-stream conditions used for the simulations were a Mach number of 7.81 and a Reynolds number of 0.28x106/m. A supersonic test case was also computed, with a free-stream Mach number of three; the supersonic case produced an oscillation consistent with the experimental results. The hypersonic results could not reproduce the oscillating flow predicted by previous experiments and DSMC. There are several reasons why this could have occurred relating to simplifications made in the model. Including the following when modeling the flow field may resolve this disagreement; modelling the flow as turbulent, including real gas effects and modeling the flow as an expanding flow.

Keywords


Fluid Mechanics; Aerodynamics

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