title: Temperature measurements in a rapid compression machine using mid-infrared H2O absorption spectroscopy near 7.6 μm.
abstract: A method for measuring the temporal temperature and number density in a rapid compression machine (RCM) using quantum cascade laser absorption spectroscopy near 7.6 μm is developed and presented in this paper. The ratios of H(2)O absorption peaks at 1316.55 cm(-1) and 1316.97 cm(-1) are used for these measurements. In order to isolate the effects of chemical reactions, an inert mixture of argon with 2.87% water vapor is used for the present investigation. The end of compression pressures and temperatures in the RCM measurements are P(C)=10, 15, and 20 bar in the range of T(C)=1000 to 1200 K. The measured temperature history is compared with that calculated based on the adiabatic core assumption and is found to be within ±5 K. The measured temporal number density of H(2)O to an accuracy of 1%, using the absolute absorption of the two rovibrational lines, show that the mixture is highly uniform in temperature. A six-pass, 5.08 cm Herriott cell is used to calibrate the line strengths in air and broadening in an Ar bath gas.
authors.affiliation: Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA. muddi@princeton.edu
authors.forename: Mruthunjaya
authors.initials: M
authors.lastname: Uddi
authors.forename: Apurba Kumar
authors.initials: AK
authors.lastname: Das
authors.forename: Chih-Jen
authors.initials: CJ
authors.lastname: Sung