Diode Laser Sensor for Scramjet Inlets

Abstract

Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE JUN 20112. REPORT TYPE This work presents test results of a diode-laser sensor for an axially symmetric inlet in a Mach 6 hypersonic flow facility. The conical inlet design presented here is more realistic than the flat plate design presented in the previous report, and is similar to the design that will be chosen as part of the Australian Space Research Program SCRAMSPACE flight test scheduled for 2012. The optical system was changed for this study to make the pitch and catch optics less sensitive to vibration, and to fit into a smaller volume than for the previous test. In addition, wavelength modulation detection was attempted with the system. Initial tests of the conical inlet design showed that it was not starting, as indicated using flow visualization images. The second version of the sensor has similar velocity sensitivity to the system used for the flat plate inlet test. The conical system was, however, still too susceptible to amplitude noise, which hinders the ability of the system to measure the free stream temperature or the angle of attack. Electrical problems with the log-ratio amplifier prevented temperature measurements for the vehicle. Preliminary vibration tests have shown that the problem is caused by independent motion between the laser and collimator when the tunnel fires. A preliminary design of a low-power lock-in amplifier for use in field experiments was completed, and tests with current inputs in place of photodiodes proved successful. SUBJECT TERMS

HITRAN/HITEMP Spectral Databases and Uncertainty Propagation by Means of Monte Carlo Simulation with Application to Tunable Diode Laser Absorption Diagnostics

“…In addition, Test Cases 2 and 3 consist of multiple absorption lines and have previously been employed by O'Bryne for measurements of a postcombustion flow at atmospheric pressures (Ref. 34). The pressure employed in the cases examined here are reduced from that of O'Bryne to better represent the exhaust of a high-speed propulsion system operating at altitude conditions.…”