A GENERALIZED MODEL OF THE DEVELOPMENT OF NONISOTHERMAL, AXISYMMETRIC FREE JETS

Abstract

A generalized model for axisymmetric free jets which allows for change in fluid density with temperature is proposed by experiment. Experimental work was carried out to obtain data on jet velocity and temperature variations over a wide range of jet-to-ambient fluid density ratio (i.e. the initial density ratio) by use of nonisothermal free jets of burned gas exhausting into quiescent air as well as isothermal free jets of CO₂-air mixture into air. Core lengths of velocity and temperature can be correlated as a function of initial density ratio and jet Reynolds number. The radial profiles of velocity and temperature in the fully-developed region can be expressed by the isothermal formulation using the corresponding jet half-radii as the characteristic radial distance. The jet half-radii and centerline decays can be described by new characteristic streamwise coordinates which take into account the effects of core length and initial density ratio. If the initial condition at the nozzle exit is specified, the present model can determine the radial distributions of velocity and temperature at any axial position.