Aerodynamic optimisation of the rear wheel fairing of the land speed record vehicle BLOODHOUND SSC

Abstract

This paper describes the design optimisation study used to aerodynamically optimise the fairings that cover the rear wheels of the Land Speed Record vehicle, BLOODHOUND SuperSonic Car (SSC). Initially, using a Design of Experiments approach, a series of Computational Fluid Dynamics simulations were performed on a set of parametric geometries, with the goal of identifying a fairing geometry that was aerodynamically optimised for the target speed of 1,000 mph. Several aerodynamic properties were considered when deciding what design objectives the fairings would be optimised to achieve; chief amongst these was the minimisation of aerodynamic drag. A parallel, finite-volume Navier–Stokes solver was used on unstructured meshes in order to simulate the complex aerodynamic behaviour of the flow around the vehicle’s rear wheel structure, which involved a rotating wheel, and shockwaves generated close to a supersonic rolling ground plane. It was found that the simple response surface fitting approach did not sufficiently capture the complexities of the optimisation objective function across the high-dimensional design space. As a result, a Nelder–Mead optimisation approach was implemented, coupled with Radial Basis Function design space interpolation to find the final optimised fairing design. This paper presents the results of the optimisation study as well as indicating the likely impact this optimisation will have on the ultimate top speed of this unique vehicle.

On the subsonic and low transonic aerodynamic performance of the land speed record car, Bloodhound LSR

“…The approach used for embedding CFD into the overall design process is outlined in Evans et al 26 The objective of the design process was to achieve a body shape that minimised the Mach-dependency of any of the aerodynamic forces or moments acting on the vehicle whilst also minimising the overall drag. Specific attention was paid to the design of the rear of the vehicle, 27,28 which was shown to be the source of much of the variations in vertical aerodynamic loads on the vehicle in the transition from subsonic to supersonic speeds. 26 The evolution of the outer mould line of the car throughout the design process is shown in Figure 2 Supersonic wind tunnel testing of the final design of Bloodhound was carried out at the Transonic Wind Tunnel Facility of the Japanese Aerospace Exploration Agency by Kleine et al 29 in 2015.…”

“…Firstly, related to the CFD modelling used in previous works 4,[26][27][28] to predict the aerodynamic characteristics of the vehicle:…”

“…Firstly, related to the CFD modelling used in previous works 4,26–28 to predict the aerodynamic characteristics of the vehicle:1. Steady RANS CFD approaches can provide aerodynamic performance predictions on accelerating, complex-geometry bodies in ground effect to a sufficient degree of accuracy to allow reasonable prediction of overall aerodynamic loads and moments acting on the vehicle even beyond the critical Mach number.2.…”