Transient velocity measurement in dusty boundary layyr developed behind a shock wave

The results of recent particle velocity measurements at the 4 x 4 inch shock tube at TRW are presented. The measurements were made in a dusty boundary layer induced by the passage of a normal shock wave over a dust bed. The dust particle velocity was measured using a single component laser velocimeter. The measurement of the transient flow was made with a fast digitizer, at a sample rate of 100 MHz. Processing of the signal was achieved through software. A number of routines for detection of acceptable signal and discrimination against background noise was developed and evaluated. The velocity time history of the dust particles behind the moving shock waves at a number of heights above the dust level were measured. Simultaneous measurement of the laser light beam extinction was used to evaluate the dust density profile behind the shock wave.