APPLICATION OF RAINBOW SCHLIEREN DEFLECTOMETRY FOR CONCENTRATION MEASUREMENTS IN AN AXISYMMETRICAL HELIUM JET

The rainbow schlieren deflectometry technique was used to measure oxyg en concentrations in a laminar, isothermal helium jet discharged verti cally into ambient air. The concentration distributions were inferred from the color schlieren image by taking into consideration the sampli ng interval and noise in measurements, especially near the jet center. Excellent quantitative agreement was reached between measurements fro m schlieren and a continuous sampling probe. This work demonstrates th e capability of the schlieren technique for providing accurate, spatia lly-resolved, nonintrusive, full-field of view measurements of species concentration in an isothermal binary system. Because the basic quant ity measured is the refractive index, the present schlieren technique can be extended for quantitative measurements of other scalar flow pro perties related to the refractive index.