Near-infrared diode laser absorption sensor for rapid measurements of temperature and water vapor in a shock tube |
| |
Authors: | H Li A Farooq JB Jeffries RK Hanson |
| |
Institution: | (1) High Temperature Gasdynamics Laboratory, Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA |
| |
Abstract: | A fast-response (100 kHz) tunable diode laser absorption sensor is developed for measurements of temperature and H2O concentration in shock tubes, e.g. for studies of combustion chemistry. Gas temperature is determined from the ratio of
fixed-wavelength laser absorption of two H2O transitions near 7185.60 cm-1 and 7154.35 cm-1, which are selected using design rules for the target temperature range of 1000–2000 K and pressure range of 1–2 atm. Wavelength
modulation spectroscopy is employed with second-harmonic detection (WMS-2f) to improve the sensor sensitivity and accuracy.
Normalization of the second-harmonic signal by the first-harmonic signal is used to remove the need for calibration and minimize
interference from emission, scattering, beam steering, and window fouling. The laser modulation depth for each H2O transition is optimized to maximize the WMS-2f signal for the target test conditions. The WMS-2f sensor is first validated
in mixtures of H2O and Ar in a heated cell for the temperature range of 500–1200 K (P=1 atm), yielding an accuracy of 1.9% for temperature
and 1.4% for H2O concentration measurements. Shock wave tests with non-reactive H2O–Ar mixtures are then conducted to demonstrate the sensor accuracy (1.5% for temperature and 1.4% for H2O concentration) and response time at higher temperatures (1200–1700 K, P=1.3–1.6 atm).
PACS 42.62.Fi; 42.55.Px; 42.60.Fc; 07.35.+k |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|