Numerous ground-test and wind-tunnel facilities are used extensively to make surface measurements of and to characterize the forces and moments encountered by aeronautics test articles. Quantitative results in these test environments are required to validate the computational fluid dynamics (CFD) tools that are used to extrapolate wind-tunnel data toward realistic flight conditions and hardware. The development of fast instrumentation and measurement capabilities that can readily be integrated into the extreme conditions present under such test conditions is one of several major technological challenges associated with the design, building, and operation of these complex test environments. Among the host of physical quantities, accurate mapping of velocity flow fields remains a significant yet essential challenge in these facilities. In addition, spatially and temporally resolved measurements of other flow parameters, such as gas density, pressure, temperature, and species mixing fractions, are of paramount importance to characterize fully the fluid dynamics. Unfortunately, the widely available current suite of flow-field probes exhibit varying degrees of intrusiveness, requiring either the physical placement of probes inside the test facility or the introduction of foreign particles or gas-phase species into the flow field. Thus, the development and application of non-invasive flow-field diagnostic probe techniques is of principal importance in these environments. This proposal expands upon our successful Phase-I results and offers an integrated package of truly cutting-edge, multidimensional, seedless velocimetry and flow diagnostics for ground-test facilities. The concepts and ideas proposed range from proof-of-principle demonstration of novel methodologies using kHz-rate femtosecond (10-15 sec) and 100-kHz-rate burst-mode picosecond (10-12 s) duration laser sources to measurements in realistic tunnel conditions expected in the current solicitation.

The proposed research program will expand upon advanced laser-based, high-data-rate, multi-dimensional, multi-parameter, noninvasive optical diagnostic platforms for NASA ground-test facilities. Such diagnostic capabilities will be a major step forward in design and model validation efforts in transonic ground-test facilities developing next-generation aerospace vehicles and air-breathing propulsion systems. During the proposed program, we will develop these measurement tools into compact, user-friendly, and mobile platforms that enable broad implementation in ground-test facilities. The expertise within this research team in state-of-the-art laser technologies, physics, and chemistry-based diagnostic techniques, and extensive product development and implementation background in defense, propulsion and energy applications will be a critical factor in realizing the proposed diagnostic platform and toolkit.

The advanced diagnostic toolkit proposed under the current program will be a significant step forward in using cutting-edge laser technology and spectroscopic approaches to address a variety of diagnostics challenges in multiple government and industrial applications. As this noninvasive optical toolkit is optimized, a major beneficiary besides NASA would be DoD test facilities developing advanced weapons systems such as supersonic fighter aircrafts, hypersonic vehicles, rockets and high-Mach number reentry vehicles. In addition, the rapidly developing commercial space industry as well as test facilities at conventional aircraft will significantly benefit by having access to such advanced multi-parameter diagnostic toolkits. Therefore, a wide market potential is expected in defense, industrial, and commercial sectors for the proposed technologies.