A numerical solution of laminar forced convection in a heated pipe subjected to a reciprocating flow

Abstract

A numerical solution is presented for laminar forced convection of an incompressible periodically reversing flow in a pipe of finite length at constant wall temperature. It is found that the four parameters that govern the heat transfer characteristics for the problem under consideration are the kinetic Reynolds number Re ω, the dimensionless oscillation amplitude A o , the length to diameter ratio LID, and the Prandtl number of the fluid. The numerical results show that annular effects also exist in the temperature profiles near the entrance and the exit of the pipe during each half cycle at high kinectic Reynolds numbers. Typical phase shifts between temperature and axial velocity at selected locations are illustrated. The averaged heat transfer rate is found to increase with both the kinetic Reynolds number and the dimensionless oscillation amplitude but decrease with the length to diameter ratio. A correlation equation of the space time averaged Nusselt number for air in terms of the three similarity parameters, Re ω, A o and LID is obtained.