Wavelength-Agile Temperature and Pressure Sensor

Progress is reported on the development of a wavelength-agile temperature and pressure sensor, a propane concentration sensor, an ethylene-based active control scheme, and a two-phase flow diagnostic. In the area of shock-tube kinetics studies, progress is reported on JP-10 ignition times and decomposition products to aid in the development of reduced chemical mechanisms. 

Previously, a multiple, fixed-wavelength sensor for measuring the gas temperature of detonation products was reported [1]. While this sensor provided important results, the rapid, broad-wavelength-scanning capabilities of advanced diode-laser technologies allow for a simpler and more robust technique to measure both temperature and pressure simultaneously [4, 5]. This technique, described below, provides gas temperature and pressure histories, spanning 2000-4000 K and 0.5-30 atm, respectively, with microsecond time response. 

Previously, a 3.39-micrometer He-Ne absorption scheme was used to measure propane concentration [7]. Sensors based on this scheme have the advantage of offering strong absorption because many fundamental bands of propane are located near the 3.39-micrometer wavelength region, but the fixed-wavelength lasers available in this region limit this sensor s applications in practical systems where interference absorption and noise are common problems. 

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