EFFECTS OF WALL TRANSPIRATION ON MIXED CONVECTION HEAT-TRANSFER IN RECTANGULAR DUCTS ROTATING ABOUT A PARALLEL AXIS

A detailed numerical study, using the vorticity-velocity method has be en conducted to examine the flow and heat transfer characteristics of wail transpiration on mired convection in the entrance region of recta ngular ducts rotating about an axis parallel to the duct axis. Thermal boundary conditions of uniform heat flux (URF) and uniform wall tempe rature (UWT) were considered. The investigation Huts presented for var ious parameters, wad Reynolds number Re-w, rotational Reynolds number J, rotational Grashof number Gd-Omega, and aspect ratio gamma. The pre dicted results disclosed that the wall transpiration effect has consid erable impact on the flow and heat transfer characteristics Results al so showed that both fRe and Nu are enhanced with an increase in J or G r(Omega), except for the range of J < 400 or Gr(Omega), < 1000. Wall t ranspiration effects are more significant for the UWT case than for th e UHF case. It is also noted that the secondary vortex induced by the buoyancy effect in the entrance region was stronger for the UWT case t han for the UHF case. In addition, the strength of the secondary vorte x is weaker for the case of the parabolic velocity condition at the in let than for the uniform velocity condition at the inlet.