Theoretical and Experimental Investigations on the Mixing of Isoenergetic Confined Co-axial Jets


Book Description

A survey of experimental results for turbulent mixing between two compressible streams in a constant area duct is presented. The experimental results are for area ratios 3 and 7.16, for velocity ratios ranging from 0.4 to 2.8, and with velocity magnitudes varying from 200 ft/sec. to 950 ft/sec. A new constant of turbulence is recommended for the theoretical analysis of the confined jet mixing which uses the free jet mixing concepts. The regions in which this analysis could be used are delineated. (Author).










Research on Mixing of Coaxial Streams


Book Description

The report presents the results of experimental and analytical investigations of the confined coaxial mixing of isoenergetic air streams. Both uniflowing and counterflowing secondary air streams are considered. Laminar and turbulent uniflow mixing are treated analytically. The results of experimental investigations of turbulent mixing are used to calculate the radial as well as the axial variations of eddy viscosity and the turbulent diffusion coefficient up to 25 jet diameters downstream of jet orifice. New expressions are developed to yield reliable values in regions of mixing where existing expressions become indeterminate. Special consideration is given to the case where the two streams have equal velocity. The experimental investigation of turbulent counterflow mixing shows that a toroidal shaped vortex is set up at the jet interface which gives rise to depressed static pressures. Over the range of parameters investigated, entrainment of fluid from the inner jet into the external stream takes place downstream of the vortex. (Author).







Research in Progress


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Journal of Aircraft


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An Investigation of Ducted, Two-stream, Variable-density, Turbulent Jet Mixing with Recirculation


Book Description

An investigation was conducted of two-stream, variable-density, turbulent jet mixing with recirculation confined within an axisymmetric duct that simulated a combustor configuration. The recirculating flow fields in the combustor simulator were the result of coaxial jet mixing between a central, primary air stream with a velocity of about 650 ft/sec and an annular secondary stream of hydrogen with velocities of 13, 23, or 48 ft/sec, depending on the desired test conditions. Experimental measurements are presented of radial distributions of time-averaged axial velocity and hydrogen mass fraction, axial distributions of time-averaged static pressure on the duct wall, axial velocity on the duct centerline, and hydrogen mass fraction on the duct wall and on the duct centerline. A theoretical study of the experimental flows was also conducted using a finite difference numerical solution technique for the calculation of viscous, recirculating flows. Comparison of theory and experiment shows that the predictive technique and the turbulence transport model require further development before accurate prediction of recirculating turbulent flows can be realized.