Browse Publications Technical Papers 2005-01-0871

Comparison of Aerodynamic Measurements on a Full-Scale NASCAR in Open and Closed Jet Test Sections 2005-01-0871

This paper reports on an exploratory automotive test which was undertaken in the NASA Langley Research Center 14 by 22 wind tunnel in the Fall of 2003. The test was collaboration between Old Dominion University, who supplied the automotive balance, NASA, who provided wind tunnel time, and Penske Racing South, who provided an instrumented test vehicle. The test generated a rather unique data set, encompassing whole body forces, surface pressures, and floor boundary layer profiles, measured on the same test article, with both an open jet and closed jet test section, utilizing the variable configuration of the 14 by 22. The nominal test velocity was 60 m/s, the nominal blockage was 7.4%, and the yaw angle ranged from −6 to +6 degrees. Results indicate substantial interference effects, as expected, with around 19% higher drag (uncorrected) in the closed configuration, relative to open. The corresponding front and rear downforce values were 14% and 13% higher respectively. A simple blockage correction to dynamic pressure is therefore not sufficient to collapse the two data sets. Detailed analysis of surface pressures and boundary layer profiles provides some insight into the reasons for this discrepancy. To support the analysis, boundary interference assessments are being made, using panel methods. In the open jet case, the current method properly accounts for the effects of jet distortion. It is concluded that relatively sophisticated on-line interference assessment techniques should be employed in tests of this type. The paper reviews both uncorrected and corrected data, the interference assessments, and explores the reasons for the inadequacy of classical blockage corrections.


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


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:

Comparison of Wind Tunnel Configurations for Testing Closed-Wheel Race Cars: A CFD Study


View Details


Development of “Aero Slit” - Improvement of Aerodynamic Yaw Characteristics for Commercial Vehicles


View Details


On the Optimisation of Road Vehicle Leading Edge Radius in Varying Levels of Freestream Turbulence


View Details