Simultaneous Measurements of Velocity and Scalar Quantity in an Axisymmetric Turbulent Jet.

In this report, we present new results of simultaneous measurements of velocity and scalar quantity in an axisymmetric turbulent jet of water solution of high Schmidt number matter. The diffusing fluid is a water solution of a commercial dye (Scs3 800), and an issuing Reynolds number is 6 400. A new combined probe of a reflection type of fiber optic concentration sensor and an I-type hot film has been developed for the simultaneous measurement of concentration and axial velocity. At first, we examined the interference effects of the fiber sensor and the hot film, and confirmed that the reliable data can be obtained when two probes are set at a distance of 0.3 mm which is smaller than the Taylor micro scale of the velocity field (x/D≥30). Then, we measured concentration and axial velocity simultaneously. It is found that the correlation between concentration fuctuation and axial velocity fluctuation has positive value in fully developed turbulent jet and that the turbulent axial mass flux on the jet centerline is in inverse proportion to the square of the downstream distance.