Arc-Jet Freestream Turbulence Characterization and its Influence on Laminar Heating Augmentation in
Abstract
For more than 60 years, arc-jet testing has served as primary basis for characterizing Thermal Protection Systems (TPS) in support o,f material development and response model validation. Arc-jet facilities provide the only ground-based means of simulating hypersoni,c heating rates (entry, re-entry, hypersonic cruise) in a reacting flow environment under flight-relevant durations. Arc-jet testing, provides data for detail material response models that can reduce uncertainty and the magnitude of thickness margins. Arc-jets are,also essential to investigate mechanical failure modes including erosion, spallation, and losses related to shear effects. The abili,ty to perform accurate experiments using arc-jet facilities is tightly coupled with the necessity of a careful characterization of t,he resulting plasma flow. The high uncertainties associated with this class of flows strongly impact the development of new TPS as w,ell as the progress in the fundamental understanding of associated gas-surface interaction phenomena. The flow characterization in r,epresentative conditions (including thermo-chemical non-equilibrium), and the use of advanced diagnostic tools to study the chemistr,y and physics of the boundary layer is of primary importance. Although arc-jet tests are indicative of how well a material will perf,orm in extreme aerothermal heating environments, it has not been possible to directly relate arc-jet test results to flight applicat,ions. The main obstacle has been an inability to fully characterize the flow.The objective of the proposed research is to characteri,ze the freestream turbulence in arc-jet flows using state-of-the-art laser-based diagnostic techniques and to investigate its influe,nce on laminar heating augmentation in the stagnation region, thereby improving our understanding of the relationship between arc-je,t test and flight environments. Flow properties including velocity, characteristic temperature, and species concentration, will be m,easured over a range of facility operating conditions. Several measurement capabilities including femtosecond two-photon absorption,laser-induced fluorescence (fs-TALIF), femtosecond laser electronic excitation tagging (FLEET) velocimetry, and Coherent anti-Stokes, Raman Spectroscopy (CARS) will be utilized and developed for the proposed, quantitative, measurements. The successful completion of, this project will result in an improved understanding of the interdependence of different modes of turbulence in arc-jet flows and,their effects on laminar heating augmentation in the stagnation region, ultimately improving the testing and design of advanced ther,mal protection systems.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 08, 2022
- Source ID
- N000142212460
Entities
People
- Luca Maddalena
Organizations
- Office of Naval Research
- United States Navy
- University of Texas at Arlington