title: Spatially resolved gas phase composition measurements in supersonic flows using tunable diode laser absorption spectroscopy.
abstract: We used a tunable diode laser absorption spectrometer to follow the condensation of D(2)O in a supersonic Laval nozzle. We measured both the concentration of the condensible vapor and the spectroscopic temperature as a function of position and compared the results to those inferred from static pressure measurements. Upstream and in the early stages of condensation, the quantitative agreement between the different experimental techniques is good. Far downstream, the spectroscopic results predict a lower gas phase concentration, a higher condensate mass fraction, and a higher temperature than the pressure measurements. The difference between the two measurement techniques is consistent with a slight compression of the boundary layers along the nozzle walls during condensation.
authors.affiliation: Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280, USA.
authors.forename: Paolo
authors.initials: P
authors.lastname: Paci
authors.forename: Yury
authors.initials: Y
authors.lastname: Zvinevich
authors.forename: Shinobu
authors.initials: S
authors.lastname: Tanimura
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Wyslouzil
authors.forename: Mark
authors.initials: M
authors.lastname: Zahniser
authors.forename: Joanne
authors.initials: J
authors.lastname: Shorter
authors.forename: David
authors.initials: D
authors.lastname: Nelson
authors.forename: Barry
authors.initials: B
authors.lastname: McManus