There is an unsatisfied demand for instrumentation with capabilities for nonintrusive, accurate direct measurements of transport and thermodynamic parameters in the high-speed flow, hyperthermal environment of NASA Arc Jet Complex facilities. Atomic and molecular-based optical diagnostics have been demonstrated to provide unprecedent insight into the dynamics and transport phenomena of reactive and non-reactive flows at spatio-temporal scales inaccessible to traditional (mostly intrusive) flow probes. High repetition rate femtosecond (fs) lasers and high-speed imaging systems have equipped them with new capabilities and new laser-based diagnostics have emerged. However, no single measurement technique can capture and quantify all the phenomena and variables of interest over a wide range of operational conditions.
We will develop and deliver a mobile multifunctional optical diagnostic platform for non-intrusive, quantitative imaging of relevant gas parameters in arc driven and other high enthalpy ground testing facilities. The platform is powered by a single fs laser and implements and integrates three state-of-the art optical diagnostic techniques: Two Photon Absorption Laser Induced Fluorescence (TALIF), a coherent anti-Stokes Raman scattering (CARS) and Femtosecond Laser Electronic Excitation Tagging (FLEET). The core laser system enables kHz rate nonintrusive measurements of species density, nonequilibrium temperature and velocity. Multiple measurements can be achieved at reduced implementation and operational costs. Such direct experimental data are essential for validating predictions, and for the design and testing of thermal protection systems.
The multifunctional optical diagnostic platform for kHz rate density, temperature and flow velocity measurements will find direct applications in the high enthalpy arc jet facilities within the NASA Ames Arc Jet Complex (IHF, PTF, TFD, AHF). More direct applications are open to other high enthalpy facilities within NASA.
There are two important features of the system (operational performance range, modular design) which allow for expanding the area of applicability into the NASA wind tunnel testing infrastructure.
A robust and versatile multimodal optical diagnostic prototype will find commercial applications in fields such as aerospace, combustion and plasma physics. Using a single laser as a source for several diagnostics make this system attractive because of a reduced size and price, and the fact that it is mobile makes it versatile for use in facilities with more than one laboratory.