Aerodynamic optimisation of a hypersonic reentry vehicle based on solution of the Boltzmann–BGK equation and evolutionary optimisation

Abstract Over the past decade there has been a surge in the interest, both academic and commercial, in supersonic and hypersonic passenger transport. This paper outlines an original approach for solving the problem of optimal design and configuration of a space vehicleoperating in rarefied hypersonic flow. The approach utilises a novel flow solverbased on the solution of the Boltzmann–BGK equation. For the first time this solverhas been coupled to an evolutionary optimiser to assist in navigation of the unfamiliar hypersonic design space. The Boltzmann–BGK solveris rigorously tested on a number of examples and is shown to handle rarefied gas dynamicsexamples across a range of length scales. The examples, presented here for the first time, include: a Riemann-type gas expansion problem, drag prediction of a nano-particle and supersonic flow across an aerofoil. Finally the solveris coupled to the evolutionary optimiser Modified Cuckoo Searchapproach. The coupled solver-optimiser design tool is then used to explore the optimum configuration of the forebody of a generic space reentryvehicle under a range of design conditions. In all examples considered the flow solverproduces valid solutions. It is also found that the evolutionary optimiser is successful in navigating the unfamiliar design space.