This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Determining Blockage Corrections in Climatic Wind Tunnels Using CFD
Technical Paper
2003-01-0936
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Computational Fluid Dynamics (CFD) was applied to investigate blockage effects (or velocity correction) in a climatic wind tunnel (CWT) test environment. Different blockage effects in the CWT were modeled using four simplified vehicles that approximated a sedan, an SUV, a pickup truck, and a minivan. Blockage dependence on nozzle size and spacing between the nozzle exit plane (NEP) and the vehicle were also investigated. The study quantified the blockage effect using different correction methods based on vehicle frontal velocity profiles and upper surface pressure traces. The blockage-free solution was also simulated for each vehicle in an ‘open road’ or free air condition.
The CFD study revealed that all the test cases resulted in blockage correction factors, defined by Vactual/Vsimulated greater than 1.0. This is a condition in which the uncorrected wind tunnel velocity was higher than the ‘open road’ condition. It was determined that vehicles with higher CDAF values induced higher blockage correction factors. The blockage correction factor increased exponentially as the vehicle was positioned closer to the NEP. Small differences in the blockage factor between the frontal velocity profile method and the upper vehicle surface pressure trace method were found. These results led to two unified CWT blockage correlations based on the vehicle frontal velocity profiles and the upper surface pressure traces. Each correlation is valid across a range of vehicle frontal areas, drag coefficients, and separation distances between the nozzle exit plane and the vehicle.
Recommended Content
Authors
Citation
Yen, J., Martindale, W., Duell, E., and Arnette, S., "Determining Blockage Corrections in Climatic Wind Tunnels Using CFD," SAE Technical Paper 2003-01-0936, 2003, https://doi.org/10.4271/2003-01-0936.Also In
SAE 2003 Transactions Journal of Passenger Cars - Mechanical Systems
Number: V112-6; Published: 2004-09-15
Number: V112-6; Published: 2004-09-15
References
- Merker, E. Wiedemann, J. On the Correction of Interference Effects in Open Jet Wind Tunnels, SAE Paper 960671
- Kuenstner, R. Deutenbach, K-R Vagt, J-D Measurement of Reference Dynamic Pressure in Open-Jet Automotive Wind Tunnels. SAE Paper 920344
- SAE Standards Committee - Open Jet Wind Tunnel Adjustments, Aerodynamic Testing of Road Vehicles in Open Jet Wind Tunnels,” SAE SP-1465 May 1999
- Hucho, W.H, Aerodynamics of Road Vehicles 1st English Edition Butterworth, Cambridge 1987
- Rout, R. K. Unique Correlation Technique for Real- World Flow Simulation in the Wind Tunnel,” SAE- Paper 980033
- Walter, J. Duell, E. Martindale, W. Arnette, S. Nagle, P. "The Driveability Test Facility Wind Tunnel No. 8,” SAE Paper 2002-01-0252