An Experimental And Analytical Study Of Coaxial Jet Mixing PDF Download

A program of experimental and analytical research to study coaxial jet mixing was initiated. Test apparatus was designed, and a test plan was developed. The apparatus provides for an axisymmetric primary stream which simulates the exhaust of a fuel-rich rocket motor and a coaxial secondary stream of air. Both streams are contained by a constant area duct. Wide variations of composition, temperature and velocity can be systematically imposed on the primary stream, and the temperature and velocity of the secondary stream can be varied. A broad permutation of flow and composition parameters involving the primary and secondary streams has been planned. The results of the reanalysis of early single particle boron combustion data were analyzed in terms of a more sophisticated model of the combustion process. Three phases of boron combustion are identified: (1) a heatup phase marked by convective heat flux into the particle; (2) an ignition phase in which surface reactions as well as convection control particle temperature; and (3) a combustion phase where particle temperature has reached the boiling point of its oxide. Estimates of both heatup time and ignition time are in good agreement with experimental data. Preliminary results of an analysis to determine the effect of particles on the mixing of compressible streams are given in terms of jet spreading parameters for the primary and secondary streams and the particle boundary in the mixing zone. (Author).