Seeding materials for use in laser anemometry

J. lntroduct lQ& A study was conducted to find a seed particle suitable for laser anemometry in the Compressor Research Facility (CRF), Wright-Patterson Air Force Base, Ohio. Prospective seeding materials were evaluated and tested to ensure that both the laser anemometer and the CRF requirements were met. A Laser Transit Anemometer (LTA) was used to measure the velocity lag that particles experience in response to an oblique shock wave. The oblique shock wave was created by a wedge with a 10 degree turning angle in a Mach 2.0 flow. Specifically, the velocity lags of 0.8 micron diameter polystyrene latex (PSL) and 0.9 micron diameter glycerin particles were measured to be 4 mm and 6 mm, respectively. The PSL followed the flow with 33% more accuracy than did the glycerin. Further development of the glycerin seed injection system will be investigated in the future with the goal of minimizing the velocity lag of glycerin. u