A Miniature Onboard Seedless Boundary Layer Velocimeter (SBLV) for High Speed Flows

We propose small, highly responsive and rugged multi-point, multi-component velocity instrumentation for velocity measurements in supersonic and hypersonic boundary layers. The sensor does not require seeding. It will provide instantaneous measurement of boundary layer profiles for high speed ground testing and for airborne applications. The proposed instrumentation is based on the well-developed Filtered Rayleigh Scattering Velocimetry technique. The proposed "Seedless Boundary Layer Velocimeter (SBLV)" will accurately and non-intrusively measure three velocity components in as many as twenty locations with a spatial resolution of the order of 30 microns. The velocimeter will incorporate specially designed diffractive optical elements resulting in a boundary layer profiler with no moving parts and a very small footprint. High power narrow-line slightly diverging laser beam together with efficient design of the sensor optics will allow detection of scattered light from gas molecules. During the Phase I, a multi-location SBLV prototype will be fabricated and tested in a wind tunnel. Feasibility of the concept will be established for the temporal bandwidth, spatial resolution, accuracy, ruggedness, and ease of use. During the Phase II, a complete diagnostic system for simultaneous measurement of flow velocity profile at up to 20 locations will be developed.