Base bleed has been extensively investigated for missile aerodynamics and with experience from that background in 1969 first investigations were performed in order to examine this effect with cars. Drag benefits were deduced from the mean base pressure measurements, which could be reduced by up to 30 %. This paper reports on wind tunnel tests, which have been conducted on a simple bluff body model, representing a car like shape, to investigate drag reduction opportunities from injecting low velocity air into the base region. This flow is known as base bleed. Most tests have been carried out using a square back shape. The effects of flow rate, porosity and porosity distribution over the base area have been investigated. In all cases drag is reduced with increasing bleed rate, but the optimum porosity is a function of bleed rate. A significant part of the drag reduction occurs without the bleed flow and arises from the presence of a cavity in the model. The effects of cavity size are examined for different base configurations. Some factors affecting implementation are considered.
Aerodynamic drag reduction for a simple bluff body using base bleed
Reduzierung des Strömungswiderstandes eines einfachen stumpfen Körper durch Heckausblasung
2003
7 Seiten, 12 Bilder, 11 Quellen
Conference paper
English
Aerodynamic drag reduction for a simple bluff body using base bleed
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