Browse Publications Technical Papers 2005-01-0867
2005-04-11

The Influence of a Horizontal Pressure Distribution on Aerodynamic Drag in Open and Closed Wind Tunnels 2005-01-0867

The influence on aerodynamic drag of a non-uniform, streamwise pressure distribution over the wake of an automobile model in both open-jet and closed-jet wind tunnels is considered in this paper. It has long been an unsolved issue in the theory of open-jet interference and is usually not important in closed-wall wind tunnels unless the model is very long. A new, semi-empirical approach is presented that is based on the observation that the drag changes due to a pressure gradient over a wake correlate with the empty-test-section pressure-coefficient difference between the base of the vehicle and the position of wake closure. A method is demonstrated that is able to remove the effect of the pressure gradient and that is not buoyancy related. This method is applied to a range of simplified and detailed automobile shapes at model scale and at full scale in various wind tunnels, as well as to normal flat plates. The paper presents a revision of previous approaches to the estimation of nozzle and collector blockage. Finally, and most importantly, the paper demonstrates that the differences measured between configurations in a wind tunnel with a gradient over the wake will be in error unless a correction is made for the wake distortion induced by the gradient.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 18% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

A Two-Measurement Correction for the Effects of a Pressure Gradient on Automotive, Open-Jet, Wind Tunnel Measurements

2006-01-0568

View Details

TECHNICAL PAPER

On the Application of Classical Wind Tunnel Corrections for Automotive Bodies

2001-01-0633

View Details

TECHNICAL PAPER

CFD Investigations of Wind Tunnel Interference Effects

2007-01-1045

View Details

X