A Numerical Study of Turbulent Axisymmetric Jets Flowing Into Closed Tubes

Abstract

A numerical study is reported on the turbulent jet flowing into closed tubes. In the computation the finite volume method is employed to solve the continuity and momentum equations with the use of the second-order closure model of turbulence. The computations were made for tube depths and tube widths ranging from 2 to 30 jet diameters and from 2 to 8 jet diameters, respectively. The computed decay of the jet centerline velocity agrees reasonably well with the experimental data (within 10 percent). With the use of the second-order closure model, it became clear that an isotropic assumption is still valid in the main mixing region in the tube. Moreover, the wall shear stress distributions were obtained along the side wall of a tube. Finally, it was found that the terminal stagnation pressure at the tube bottom depends strongly on the diameter of the tube for D T /D N of less than 5.