Temperature and water vapour concentration measurements of CH_4/Air premixed flat flame based on TDLAS

A sensor based on tunable diode laser absorption spectroscopy(TDLAS) was constructed for temperature and water vapor concentration measurement.Absorption lines were selected and analysed using spectrum database Hitran2004.Two fiber-coupled near infrared distributed feedback lasers was used to probe two water vapor absorption features(7168.437 cm-1 and 7185.597 cm-1) near 1393nm which has high sensitivity of temperature measurement in 500～1300K.Successful experiments were performed in a CH4/Air premixed flat flame burner using direct absorption wavelength scanned method at a 1kHz scan rate.Because of the cooler shear layer in the flat flame,mixing layer theory was applied to correct TDLAS results.Comparison with thermocouple measurements,the max difference of both methods is less than 80K(6.7%).Comparison with calculation,the average water mole fraction difference is less than 0.02(10%).