This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
On Low-Frequency Pressure Pulsations and Static Pressure Distribution in Open Jet Automotive Wind Tunnels
Technical Paper
1999-01-0813
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Avoiding low-frequency pressure pulsations and establishing a good axial static pressure distribution are primary concerns for open jet wind tunnels. The current research was conducted to ensure the full scale Chrysler Aero-Acoustic Wind Tunnel (AAWT) design is consistent with good performance in these two areas. Experiments were conducted in two tunnels: a 1/3.6-scale closed-circuit tunnel and a 1/12-scale open-loop tunnel. Results from both are consistent, and a configuration that exhibits i) minimal pulsations for both empty test section and 15% vehicle blockage and ii) a good axial static pressure distribution has been identified for the AAWT. The results illustrate the effect of open jet length, collector geometry, and plenum geometry on pulsation levels and highlight the spatial variation of the pulsation levels within the plenum chamber. Pulsation levels were observed to increase with increasing open jet length and decreasing collector throat area. For high-pulsation configurations, the resonant nature of the phenomenon is indicated by local maxima in fluctuation level (Cp,rms) at specific wind speeds. Although the physics are not fully understood, pulsations represent a coupling between the open jet shear layer and acoustic modes of part or all of the tunnel circuit. An analytical model is presented that highlights two acoustic modes that can lead to resonant fluctuations. The model predicts pulsation frequencies as a function of wind tunnel geometry. Predictions exhibit reasonable agreement with measurements. Axial static pressure measurements were acquired in the empty test section for various open jet lengths and collector configurations. A region of adverse pressure gradient is present immediately upstream of the collector inlet. For open jet 
region begins at a similar distance upstream of the collector. Given this independence of axial pressure distribution and collector throat area for these conditions, the collector throat area can be set to minimize low-frequency pressure pulsations.
region begins at a similar distance upstream of the collector. Given this independence of axial pressure distribution and collector throat area for these conditions, the collector throat area can be set to minimize low-frequency pressure pulsations.Recommended Content
| Technical Paper | Elimination of a High-Frequency Narrow-Band Noise Component in a Low-Noise Automobile Wind Tunnel |
| Technical Paper | Improved Numerical Noise Predictions for Axial Fans |
| Technical Paper | Disc-Pad Interaction Related to Brake Squeal |
Authors
Citation
Arnette, S., Buchanan, T., and Zabat, M., "On Low-Frequency Pressure Pulsations and Static Pressure Distribution in Open Jet Automotive Wind Tunnels," SAE Technical Paper 1999-01-0813, 1999, https://doi.org/10.4271/1999-01-0813.Also In
References
- Holthusen, H. Kooi, J.W. 1997 “Model and Full Scale Investigations of the Low Frequency Vibration Phenomena of the DNW Open Jet,”
- Ginevsky, A.S. 1997 “Self-Oscillation Flow Control in Free-Jet Wind Tunnels,”
- Prof. Kramer Carl
- Wiedemann, J. Wickern, G. Ewald, B. Mattern, C. 1993 “Audi Aero-Acoustic Wind Tunnel,” SAE Paper 930300
- Ahuja, K.K. Massey, K.C. D'Agostino, M.S. 1997 “Flow/Acoustic Interaction in Open Jet Wind Tunnels,”
- Mercker, E. Wiedemann, J. 1996 “On the Correction of Interference Effects in Open Jet Wind Tunnels,” SAE Paper 960671
- von Schulz-Hausmann, F.K. Vagt, J.-D. 1988 “Influence of Test-Section Length and Collector Area on Measurements in ¾-Open-Jet Automotive Wind Tunnels,” SAE Paper 880251
- Garry, K.P. Cooper, K.R. Fediw, A. Wallis, S.B. Wilsden, D.J. 1994 “The Effect on Aerodynamic Drag of the Longitudinal Position of a Road Vehicle Model in a Wind Tunnel Test Section,” SAE Paper 9940416
- Deutenbach, K.-R. 1995 “Influence of Plenum Dimensions on Drag Measurements in Open-Jet Automotive Wind Tunnels,” SAE Paper 951000
- Goenka, L. Varner, M.O. 1990 “Studies Supporting the Development of an Automotive Adaptive-Wall Wind Tunnel,” SAE Paper 900320
- Goenka, L.N. 1991 “Scale-Model Tests on the Test Section of the Chrysler Slotted-Wall Automotive Wind Tunnel,” SAE Paper 910313
- Romberg, G.F. Gunn, J.A. Lutz, R.G. 1994 “The Chrysler 3/8-Scale Pilot Wind Tunnel,” SAE Paper 940416
- Bartel, H.W. McAvoy, J.M. 1981 “Cavity Oscillation in Cruise Missile Carrier Aircraft,”
- Brown, G.L. Roshko, A. 1974 “On Density Effects and Large Scale Structures in Turbulent Mixing Layers,” Journal of Fluid Mechanics 64 775 816
- Howe, M.S. Baumann, H.D. 1992 “Noise of Gas Flows,” Noise and Vibration Control Engineering Beranek, L.L. Ver, I.L. John Wiley & Sons New York