Diode Laser Sensor for Gas Temperature and H2O Concentration in a Scramjet Combustor Using Wavelength Modulation Spectroscopy (Postprint)
STANFORD UNIV CA HIGH TEMPERATURE GASDYNAMICS LAB
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A diode laser absorption sensor which probes three spectral features of water vapor in the near infrared region to infer gas temperature and water vapor concentration near the exit of a scramjet combustor is presented. Optical engineering is used to overcome beam steering and fiber mode noise sources. A method to make absolute measurements using wavelength modulation spectroscopy WMS with second harmonic detection 2f is described, along with the advantages of the technique over direct absorption spectroscopy. Measurements using both techniques in the scramjet combustor are compared to show superior noise rejection and overall signal to noise ratios with WMS-2f. Results of temperature and water vapor partial pressure under various scramjet operating conditions show the utility of the sensor for scramjet engine design and optimization.
- Test Facilities, Equipment and Methods
- Combustion and Ignition
- Jet and Gas Turbine Engines