AFRL Scientists Develop Miniaturized Laser-Based Measurement Capabilities for Scramjet Engine Performance Analysis

  • Published
  • By Propulsion Directorate
  • AFRL/PR
WRIGHT-PATTERSON AIR FORCE BASE, Ohio --  AFRL scientists are working with Small Business Innovation Research (SBIR) partner Zolo Technologies, Inc., to prepare for the first flight test of a diode-laserbased measurement platform. The test is part of the Hypersonic International Flight Research and Experimentation (HIFiRE) program. The team has adapted and miniaturized laser-based telecommunications technologies to develop a unique measurement platform employing tunable diode laser absorption spectroscopy (TDLAS).

The TDLAS platform provides a novel approach for measuring flow properties (e.g., species concentration, velocity, combustion efficiency) in flight. The method employs KHz frequency sampling rates in order to gain maximum information from flight experiments. This effort marks the first time that the technology has undergone miniaturization for use at scales suitable for sounding rocket flight experiments (which involve mass on the order of 3 kg and power on the order of 20 W).

HIFiRE represents a 7-year bilateral agreement with Australia to conduct research in the exploration and development of fundamental hypersonic aerospace technologies. TDLAS experiments are scheduled for three of the HIFiRE sounding rocket flights. These activities will focus on developing new, flight-qualified, nonintrusive techniques capable of measuring core flow properties in real time in order to characterize critical vehicle/engine parameters, such as air mass capture, stability limits, and combustion progress.

Scientists have qualified the diode-laser flight hardware to operate over unprecedented temperature and vibration conditions. The TDLAS experiments will transition the SBIR technology from Technology Readiness Level (TRL) 2 (i.e., technology concept and/or application formulation) to TRL 4 (i.e., component and/or breadboard validation in laboratory environment) in the initial flight, scheduled for 2008. Two additional flights are slated for 2009 and 2010, respectively. The team expects that the TDLAS measurement platform will achieve TRL 6 status (i.e., system/subsystem model or prototype demonstration in relevant environment, ground or space) at HIFiRE's culminating exercise, a Mach 8 scramjet [supersonic combustion ramjet] propulsion flight.