Aerodynamic Analysis of a Two-Man Bobsleigh

This paper presents the activities performed to improve the aerodynamic performances of a two man bobsleigh. Performances during races depend on aerodynamic design and crew expertise. Bobsleigh shape design optimization has long been based on intuitive modifications driven by the individual experiences of the athletes. In this work, we exploit the techniques routinely used for race car aerodynamics optimization to find optimized aerodynamic configurations for the bobsleigh. This problem can be formulated as a constrained shape optimization since the final configuration must still comply with the regulations of the international bobsleigh federation (FIBT). We use reverse engineering techniques to get a digital model of the initial shape of the bobsleigh. Then, we add a simplified three dimensional model of the crew and we use a finite volume solver of Navier Stokes equation to simulate the flow around the bobsleigh and crew under many typical race conditions. Specifically, we simulate the flow around the bobsleigh moving either along a straight channel (with side walls) or along a bend at different velocities. Based on the detailed analysis of the aerodynamic forces acting on the bobsleigh, we evaluate the effect of bobsleigh clearance and nose shape on aerodynamic performances, identifying and testing alternative design modifications. Based on these “virtual wind tunnel tests”, an optimized profile for the shell and wings has been identified. Finally, aerodynamic tests have been performed in a wind tunnel on a scaled model of the bobsleigh and on the full scale model with and without the crew. Experimental tests confirm the results of numerical simulations and give additional useful suggestions for fine aerodynamic optimization of bobsleigh and crew during races.