Diaphragm rupture. Impingement by a conically-nosed, ram-accelerator projectile |
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Authors: | A Sasoh J Maemura S Hirakata K Takayama J Falcovitz |
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Institution: | (1) Shock Wave Research Center, Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-77, Japan , JP;(2) Institute of Mathematics, Hebrew University of Jerusalem, Jerusalem 91904, Israel , IL |
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Abstract: | The effect of diaphragm rupture by a conically-nosed projectile on the gasdynamics related to ram accelerator operation was
experimentally and numerically studied. The experiments were conducted using a 25-mm-bore ram accelerator. Either air or nitrogen
was used as the test gas. Using a high-speed image converter camera, it was observed that during the process of the diaphragm
rupture a region with strong radiation developed between the diaphragm and the approaching projectile/sabot. This radiating
region corresponds to the shock-heated gas which is originated from a precursory shock wave driven by the accelerating projectile/sabot.
The flow around the projectile upon entering the test section by rupturing the diaphragm was visualized by holographic interferometry.
During the diaphragm rupture, the system of oblique shock waves around the conical nose of the projectile was seen undisturbed
on the downstream side of the diaphragm. Under the same condition as the experiment, numerical simulation was conducted using
GRP (Generalized Riemann Problem) scheme which was extended to the computation of compressible flow fields bounded by moving
surfaces. Two diaphragm rupture models were examined: (1) the diaphragm deformed by wrapping tightly around the moving projectile;
(2) the diaphragm was ruptured instantly at the moment the projectile touched the diaphragm. Comparing these models with the
experimentally visualized flow, the former was found to express the diaphragm rupture process much better than the latter.
Received 9 February 1998 / Accepted 9 September 1998 |
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Keywords: | :Diaphragm rupture Ram accelerator Moving boundary Holographic interferometry Precursory shock wave |
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