LAMINAR MIXING OF HETEROGENEOUS AXISYMMETRIC COAXIAL CONFINED JETS

Confined laminar mixing of dissimilar circular axisymmetric jets is studied. The system considered is binary, isothermal, and nonreacting. The central jet consists of slow-moving light gas. This system is characteristic of gas-core nuclear reactor where minimum mixing is desired. The boundary-layer equations are used to describe the confined jet mixing problem and the solution is obtained numerically by an explicit finite difference scheme. Solutions were obtained for a wide range of velocity ratio, density ratio, radius ratio, viscosity ratio, and outer stream Reynolds and Schmidtnumber. Results are obtained in the form of velocity and mass fraction fields, and radial profiles for some typical runs are presented. The results show that an increase in the jet velocity U//1 causes an increase of the mass fraction potential core length Lw, slower decay of the centerline velocity and mass fraction, and a wider jet as well as larger developing length. Further, an increase in the jet density p//1 reduces the centerline velocity in the mixing region and increases the developing length.