Non-Intrusive Water Vapor Sensor for Industrial Process Flows

An in-situ sensor is described for non-intrusive water vapor measurements in industrial process flows. Based on an existing room-temperature diode laser source, prototype versions have demonstrated room temperature applications with over four orders of magnitude linear dynamic range and limiting detectivities approximately 10E13 per cubic centimeter in compact cells. Dual-beam absorption measurements are made in a wavelength scanning mode in conjunction with a novel noise-canceling detector technology to deliver near shot-noise-limited performance in variable pressure and temperature flows. In the Phase I portion of the program, a modified prototype will be used to demonstrate approximately 0.1 grain/lbm sensitivity throughout the typical pressure and temperature ranges of aeropropulsion inlet flows. These data will be used to complete detailed designs for deliverable sensors in the Phase II effort.