Unsteady drag force measurement in shock tube
An aerodynamic force measurement technique with an extremely short test time was developed. A signal recovery method based on frequency domain de-convolution technique was applied on a direct acceleration measurement with a weakly-restrained test model. With the technique, an unsteady drag force of an 80mm diameter sphere model was measured when a planar shock wave of M s=1.22 passed the sphere in a vertical shock tube of 300 × 300mm square cross section. The measured drag force was evaluated with a numerical simulation, the reliability of which was verified with pressure and optical measurements. The evaluation revealed that the present force measurement technique has enough accuracy and time resolution for phenomenon with a duration of a few hundred μS. Additionally, the unsteady force measurement of a sphere revealed that drag force had been negative for approximately two hundred μs after the shock wave passed over the sphere. Numerical analysis showed that this negative drag was caused by the high pressure produced by shock waves converging at the lower part of the sphere.
KeywordsShock Wave Drag Force Shock Tube Force Measurement Incident Shock Wave
Unable to display preview. Download preview PDF.
- 1.L. Bernstein: Force measurement in short-duration hypersonic facilities. AGARDograph AGARD-AG-214 (1975)Google Scholar
- 2.M. Bredin, B. Skews: ‘The Measurement of Drag in Unsteady Compressible Flow’. In: Proc 23rd Int Symp on Shock Waves, Arlington, 2001, pp. 463–471Google Scholar
- 3.A. Britan, T. Elpherin, O. Igra, R Jiang: Acceleration of a sphere behind planar shock waves, Experiments in Fluid 20, 84 (1995)Google Scholar
- 4.O. Igra, K. Takayama: Shock tube study of the drag coefficient of a sphere in a non stationary flow. Proc R Soc Lond A442, 231 (1993)Google Scholar
- 5.G. Rodriguez, P. Grandeboueuf, M. Khelifi, J.F. Haas: ‘Drag Coefficient Measurement of Spheres in a Vertical Shock Tube and Numerical Simulation’. In: Proc 20th Int Symp on Shock waves, Marseille, 1995, pp. 43–48Google Scholar
- 6.M. Takahashi, S. Ueda, T. Tomita, H. Tamura: Transient flow simulation of a compressed truncated perfect nozzle. AIAA Paper 01-3681 (2001)Google Scholar