Thesis

An investigation into base bleed for drag reduction in bluff two-box sports utility vehicles

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Awarding institution
  • University of Strathclyde
Date of award
  • 2009
Thesis identifier
  • T13111
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Department, School or Faculty
Abstract
  • The purpose of this project was to investigate the concept of 'base bleed' when used on two-box bluff-body sports utility vehicles (SUVs). The project was set up in collaboration with Jaguar-Land Rover, with emphasis on the use of base bleed on a Land Rover Discovery Mk III. Base bleed is generally defined as a method of reducing the drag of an object in motion via the introduction of air or some other gas to the rearward low pressure region. In the case of this project, a supplementary air source was applied to test this effect. The project involved computational fluid dynamics (CFD) and wind tunnel testing. A computer-model was generated through use of a Konica VI-9i Non-Contact 3-D digitizer and a scale model. Geomagic Studio 10 was used to manipulate the scanned point-cloud data into a useable 3-D model. Pre-processing for CFD was carried out in Gambit and CFD analysis was carried out using Fluent. This paper shows that the reduction in drag increases to a certain point as the mass flow rate of air is increased and the flow is deflected at the outlet. By controlling the turbulent wake to the rear of the vehicle, it is shown in the paper that Cq of 0.035 (mass flow rates of under 0.76kg/s) can reduce drag coefficient by 9.1% with an outlet on the side of the vehicle, and that a Cq of 0.019 (mass flow rate of under 0.2kg/s) can reduce the drag coefficient by 5.5% for a small outlet on the upper section of the rear of the vehicle. It was also found through wind tunnel testing that the drag may be reduced further by the bleed outlet cavity that was not simulated in the CFD method employed. Throughout the investigation, the feasibility of base bleed being applied to a production vehicle was considered.
Resource Type
DOI
Date Created
  • 2009
Former identifier
  • 946468

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