CONVECTION HEAT-TRANSFER OF CLOSELY-SPACED SPHERES WITH SURFACE BLOWING

A validated computer simulation model has been developed for the analy sis of colinear spheres in a heated gas stream. Using the Galerkin fin ite element method, the steady-state Navier-Stokes and heat transfer e quations have been solved describing laminar axisymmetric thermal flow past closely-spaced monodisperse spheres with fluid injection. Of int erest are the coupled nonlinear interaction effects on the temperature fields and ultimately on the Nusselt number of each sphere for differ ent free stream Reynolds numbers (20 less-than-or-equal-to Re less-tha n-or-equal-to 200) and intersphere distances (1.5 less-than-or-equal-t o d(ij) less-than or equal-to 6.0) in the presence of surface blowing (0 less-than-or-equal-to v(b) less-than-or-equal-to 0.1). Fluid inject ion (i.e. blowing) and associated wake effects generate lower average heat transfer coefficients for each interacting sphere when the Reynol ds number increases (Re > 100). Heat transfer is also reduced at small spacings especially for the second and third sphere. A Nusselt number correlation for each interacting (porous) sphere has been developed b ased on computer experiments.