Design, Operation and Preliminary Results of the BRL Expansion Tube
[Technical Report, Technical Report]
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
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The paper describes the Ballistic Research Laboratories BRL expansion tube, which was built for interferometric observation of hypersonic flow fields. The optical instrumentation consists of a Mach-Zehnder interferometer in conjunction with a rotating mirror and frame camera. By means of simultaneous streak interferometry the free stream conditions are monitored and determined for each test run. With the free stream condition known, the frame interferogram of the flow around the model can be evaluated to give density or electron density field around the model. Examples of density distribution in the free stream are shown for two typical cases, with flow velocity of approx. 10,000 and 20,000 ftsec, respectively. The density distribution within the shock layer of a reacting flow is shown and compared with theoretical prediction. Conical flow tests are performed in an attempt to assess the free stream turbulence. The effects of second diaphragm and the flow contamination are discussed.
- Test Facilities, Equipment and Methods
- Fluid Mechanics