Vehicle wakes subject to side wind conditions
Vehicle wakes are often studied by comparing different configurations. The number of designs and possible combinations to be investigated is often limited due to time constraints. Instead of limiting the possible designs, optimisation was used to aid in the development of a low-drag reference geometry. A surrogate model-based optimisation method was developed and benchmarked against other common techniques. The surrogate model featured adaptively scaled Radial Basis Functions which performed well for the tested benchmark problems. The developed algorithm was used to optimise the geometry at the rear of a vehicle at yaw. This resulted in unexpected designs with good performance.
The investigated geometries featured a base cavity with small angled surfaces, or kicks, at the trailing edge. This kick angle altered the wake balance, reducing the sensitivity to side wind. The wake's unsteady behaviour changed when altering the cavity. Based on the results, it was not possible to find a consistent trend of the unsteadiness of the wake and its relation to drag alone. The results indicate that the improvements to the base pressure were primarily a result of altering the wake balance. The wake balance proved to be the most reliable indicator of drag, with and without additional side wind.
Latin Hypercube Sampling
real world conditions
Proper Orthogonal Decomposition
wind averaged drag
Radial Basis Functions
Chalmers, Mekanik och maritima vetenskaper, Fordonsteknik och autonoma system
Numerical analysis of a vehicle wake with tapered rear extensions under yaw conditions
Journal of Wind Engineering and Industrial Aerodynamics,; Vol. 179(2018)p. 308-318
Artikel i vetenskaplig tidskrift
Strömningsmekanik och akustik
Thesis for the degree of Licentiate – Department of Mechanics and Maritime Sciences: 2019:09
Chalmers tekniska högskola
Opponent: Prof. Jens Fransson, KTH – Royal Institute of Technology, Sweden