Unsteady drag on a sphere by shock wave loading

The dynamic drag coefficient of a sphere by shock wave loading is investigated numerically and experimentally. The diameter of the sphere is varied from 8 \({\mathrm{\mu}}\)m to 80 mm in numerical simulation. The axisymmetric Navier-Stokes equations are solved on a fine grid, and the grid convergence of the drag coefficient is achieved. The numerical result is validated by comparing the experimental data of a 80 mm sphere, measured by the accelerometer in a vertical shock tube. It is found that the sphere experiences in the early interaction one order higher drag than in the steady state. A transient negative drag, mainly resulting from the focusing of shock wave on the rear side of the sphere, is observed only for high Reynolds number flows, and the drag becomes positive because of increased skin friction for low Reynolds number flows.

Authors and Affiliations

1. Institute of Fluid Science, Tohoku University, 980-8577, Sendai, Japan

   M. Sun & K. Takayama

2. Dept. Mechanical Systems Engineering, Muroran Institute of Technology, 27-1 Mizumoto-cho, 050-8585, Muroran, Japan

   T. Saito

3. National Aerospace Laboratory, Kakuda Space Propulsion Laboratory, 1-Koganesawa, Kimigaya, Kakuda, Japan

   H. Tanno

Corresponding author

Correspondence to M. Sun.

Communicated by O. Igra

Received: 10 March 2004, Accepted: 24 May 2004, Published online: 20 August 2004[/PUBLISHED]

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