This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Correction of Nozzle Gradient Effects in Open Jet Wind Tunnels
Technical Paper
2004-01-0669
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
In open jet wind tunnels with high blockage ratios a sharp rise in drag is observed for models approaching the nozzle exit plane. The physical background for this rise in drag will be analyzed in the paper. Starting with a basic analysis of the dependencies of the effect on model and wind tunnel properties, the key parameters of the problem will be identified. It will be shown using a momentum balance and potential flow theory that interaction between model and nozzle exit can result in significant tunnel-induced gradients at the model position.
In a second step, a CFD-based investigation is used to show the interaction between nozzle exit and a bluff body. The results cover the whole range between open jet and closed wall test section interaction. The model starts at a large distance from the nozzle, then moves towards the nozzle, enters the nozzle and is finally completely inside the nozzle. The results for the open jet and closed wall cases correspond to the results expected by classical wind tunnel correction theory. The drag level for the model entering the nozzle exit plane is shown to be significantly higher than the drag observed for closed walls. This highlights the existence of an additional drag mechanism not related to the dynamic pressure.
In a third step, the CFD results and additional experimental results are used to validate the newly derived correction formula for the effect of the nozzle gradient. Using well-known benchmark cases from the literature it will be shown, that the proposed correction eliminates the effects of nozzle proximity almost completely.
Recommended Content
Citation
Wickern, G. and Schwartekopp, B., "Correction of Nozzle Gradient Effects in Open Jet Wind Tunnels," SAE Technical Paper 2004-01-0669, 2004, https://doi.org/10.4271/2004-01-0669.Also In
SAE 2004 Transactions Journal of Passenger Cars: Mechanical Systems
Number: V113-6; Published: 2005-07-05
Number: V113-6; Published: 2005-07-05
References
- SCHWARTEKOPP, B DaimlerChrysler Wind Tunnel Data SAE Subcommittee No. 9 Meeting (Aerodynamic Testing of Road Vehicles in Open Jet Wind Tunnels) April 1997 Stuttgart 1997
- WICKERN, G. LINDENER, N. The Audi Aeroacoustic Wind Tunnel: Final Design and First Operational Experience SAE Technical Paper 2000-01-0868 2000
- KOPP, S. Experimentelle und theoretische Untersuchungen im Hinblick auf eine Blockierungs-korrektur für Automobilwindkanäle mit Freistrahlmeßstrecke Diplomarbeit am Lehrstuhl für Fluidmechanik (Experimental and Theoretical Investigations with Respect to a Blockage Correction for Automotive Wind Tunnels with Open Jet Test Section) TU München 1997
- SCHULZ-HAUSMANN, F.K. v. VAGT, J.-D. Influence of Test Section Length and Collector Area on Measurements in Three-Fourths Open Jet in Automotive Industry SAE Technical Paper 880251 Detroit 1988
- HOFFMAN, J.A. MARTINDALE, B. ARNETTE, S.A. WILLIAMS, J. WALLIS, S. The Effect of Test Section Configuration on Aerodynamic Drag Measurements SAE Technical Paper 2001-01-0631 2001
- KUECHEMANN, D. VANDREY, F. Ueber den Einfluss der Duese auf Widerstandsmessungen im Freistrahl II (On the effect of the nozzle on the result of drag measurements, Part II) ZAMM 22 15 22 1942
- MERCKER, E. WIEDEMANN, J. On the Correction of Interference Effects in Open Jet Wind Tunnel SAE Technical Paper 960671 Detroit 1996
- SCHWARTEKOPP, B. Remarks on nozzle-blockage correction 4 th ECARA Blockage Subgroup meeting Stuttgart 2000
- WICKERN, G. On the Application of Classical Wind Tunnel Corrections for Automotive Bodies SAE Technical Paper 2001-01-0633 Detroit 2001
- NIJHOF, B.C. WICKERN, G. Reference Static and Dynamic Pressures in Automotive Wind Tunnels SAE Technical Paper 2003-01-0428 Detroit 2003
- YANG, Z. SCHENKEL, M. FADLER, G.J. Corrections of the Pressure Gradient Effects on Vehicle Aerodynamic Drag SAE Technical Paper 2003-01-0935 Detroit 2003
- YEN, J.C. MARTINDALE, W.R. DUELL, E:G: ARNETTE, S.A. Determining Blockage Corrections in Climatic Wind Tunnels using CFD SAE Technical Paper 2003-01-0936 Detroit 2003
- JEHLE, E. Strömungsstrukturerkennung auf der Basis von numerischen 3D Navier-Stokes-Simulationen zur Einbindung in den Fahrzeugentwicklungsprozess (Recognition of Flow Topology Based on 3D Navier-Stokes-Simulations for the Implementation in the Vehicle Development Process University of Karlsruhe 2001
- LOMBARDI, G. CARMASSI, S. Wall Interference Effects: Analysis and Correction for Automotive Wind Tunnels 4 th MIRA Aerodynamic Conference Birmingham 2002
- EWALD, B. Wind tunnel wall corrections AGARDograph 336 1998
- GLAUERT, H. Wind tunnel interference on wings, bodies and airscrews ARC, R.&M. 1566 1933
- GARNER, H. C. Subsonic wind tunnel wall corrections AGARDograph 109 1966
- LOCK, C.N.H. The interference of a wind tunnel on a symmetrical body ARC, R.&M. 1275 1929
- GLEASON, M. E. Uncertainty in Automotive Experimental Aerodynamics 2002 SAE Conference Detroit 2002
- GÜRTLER, T. EADE Correlation Test 1999 EADE-Meeting at MIRA Coventry 2000