TRANSONIC FLOW FIELD MEASUREMENT SCHEME DEVELOPMENT

LITTLE INSTRUMENTATION IS AVAILABLE TO MEASURE THE FLOW PARAMETERS OF TRANSONIC OR SUPERSONIC FLOWS IN WIND TUNNELS OR COMBUSTION CHAMBERS. COMMERCIAL LASER DOPPLER VELOCIMETERS BECOME INCREASINGLY INACCURATE FOR HIGH MACH NUMBERS BECAUSE THEY RELY ON SCATTERING FROM LARGE PARTICLES WHICH CANNOT FOLLOW THE FLOW THROUGH TURBULENCE OR SHOCKS. THE TESTING OF TRANSONIC AIRFOILS OR SCRAMJET ENGINES REQUIRES VELOCITY, DENISTY, AND TEMPERATURE INFORMATION FOR THE FLOW WHICH CAN BE OBTAINED THROUGH THE APPLICATION OF LASER INDUCED FLUORESCENCE TECHNIQUES WHICH INTERROGATE THE MOLECULES OF THE FLOW ITSELF. SOME OF THESE TECHNIQUES HAVE BEEN DEVELOPED TO AN ADVANCED STATE IN RESEARCH LABORATORIES. IT IS ALSO POSSIBLE TO OBTAIN SIMULTANEOUS MEASUREMENTSOF TWO FLOW PARAMETERS SUCH AS VELOCITY AND TEMPERATURE (REQUIRED FOR THE SOLUTION OF THE TIME-AVERAGED NAVIER-STOKES EQUATIONS). WE PROPOSE TO SELECT A TARGET MOLECULE AND PERFORM A CONCEPTUAL DESIGN STUDY FOR A SYSTEM WHICH PROVIDES AN OPTIMUM CAPABILITY FOR MEASURING THE VELOCITY, DENSITY, AND TEMPERATURE IN THE TRANSONIC REGION FOR AIRFOIL AND SCRAMJET TESTING. IN THE PHASE II EFFORT, WE WOULD DEVELOP THIS DESIGN INTO A PROTOTYPE INSTRUMENT AND BEGIN INITIAL TESTING IN AN AIRFLOW.