High-Speed Noninvasive Multi-Parameter Laser Diagnostics for High-Mach-Number Flows

Numerous ground test and wind tunnel facilities are used extensively to generate forces and moments as well as surface measurements of test articles required to validate computational tools used to extrapolate wind tunnel data to realistic flight conditions and hardware. Accurately mapping velocity flow fields remains a significant challenge in these facilities. In addition, spatially and temporally resolved measurements of flow parameters such as density, pressure, and temperature are of paramount importance. Intrusive probe type devices disturb the flow field while traditional particle-seeded techniques are not feasible in shock layers or stagnation regions. Seeded molecular tagging approaches can not only alter the mean flow, but also introduce unsteady disturbances and requires sufficient upstream seeding in order to diffuse into the boundary layer. Additionally, seeding can contaminate the tunnels, can become expensive, and reduce the effective run time. This proposal offers an integrated package of truly cutting-edge, multidimensional, seedless velocimetry and flow diagnostics for ground test facilities. The concepts and ideas proposed are ranging from proof-of-principles demonstration of novel methodologies using kHz-rate femtosecond (10-15 sec) duration laser sources to measurements in realistic tunnel conditions expected in the current solicitation. In addition, the technologies and tools developed will be packages into robust and user-friendly testing platforms enabling dual use capability in both ground and inflight-test environments.