Shock-Tube Performance at Low Initial Pressure
An electron beam densitometer was used to investigate the behavior of a conventional 1 1/8-in. ID shock tube operating at initial pressure of the order of 1 mm Hg. These experiments show that such a shock tube does not perform as predicted by simple theory. Most of the experiments were performed in argon with shock Mach numbers ranging between 1.2 and 7.0. The most striking observation was that for a given shock velocity, M/sub s/ = 1.6. the distance between the shock wave and contact surface as observed at the densitometer was proportional to lenght over a tenfold range or tube length. At an initial pressure of 0.5 mm Hg the time interval between the arrival of the shock and the contact surface varied between 600 mu sec at M/sub s/ = 1.2 and 20 mu sec at M/sub s/ = 7.0. The diaphragm pressure ratio (Ar-- Ar) required to produce a shook of velocity M/ sub s/ = 1.6 varied from 200 at an initial pressure of 0.25 mm Hg to 20 at an initial pressure of 50 mm Hg. For a given diaphragm pressure ratio the shock velocity decreased with distance in a highly nonlinear manner. The density behind the shock wave was observed to increase signficantly before the arrival of the contact surface under all conditions. This surprising hock-tabe behavior is believed to be related to severe shock-tabe behavior is believed to be related to severe laminar boundary layer development behind the shock wave at low initial pressures.
- Research Organization:
- Los Alamos Scientific Lab., N. Mex.
- Sponsoring Organization:
- USDOE
- NSA Number:
- NSA-13-011327
- OSTI ID:
- 4248951
- Journal Information:
- Physics of Fluids (New York), Journal Name: Physics of Fluids (New York) Journal Issue: 2 Vol. 2; ISSN 0031-9171
- Publisher:
- American Institute of Physics
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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SHOCK-WAVE CURVATURE AT LOW INITIAL PRESSURE