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Title: The simulation of transient cross-wind gusts and their aerodynamic influence on passenger cars
Author: Ryan, Anthony G.
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2000
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The unique University of Durham transient cross-wind facility has been developed such that sharp edged, finite length, cross-wind gusts with a relative yaw angle of 22' can be developed at the rate of 1000/hr. This cross-wind facility uses the transient interaction of two wind tunnel jets to create these gusts, with the fully automated, rapid, repeatable gust production process allowing ensemble averaging to significantly improve data quality. The cross-wind gust characteristic, as observed for the empty working section, has some inherent problems. A yaw angle undershoot, and more importantly, an overshoot occur at the leading edge of the gust. A transient total pressure overshoot is also observed at the leading edge of the gust. Computational fluid dynamics (CFD) simulations of the empty working section have replicated these anomalies, and suggestions are proposed for their elimination. Two aerodynamic models were tested in this facility, each being subjected to transient cross-wind gusts of 10 model lengths. Both models exhibited significant transient force and moment overshoots. These overshoots were found to be a consequence of delayed pressure development in regions of separated flow, with full flow development requiring up to seven model lengths of cross-wind gust. These results, which cannot be replicated by any steady testing procedure, confirm the requirement for transient testing, if transient forces and moments are required.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Aerodynamics Fluid mechanics Vehicles