Turbulent Film Condensation on an Isothermal Sphere

摘要

An investigation is presented of turbulent film condensation on a sphere. It begins by considering the case of vapor flow past an isothermal sphere. The high tangential velocity of the vapor flow at the boundary layer is determined from potential flow theory. The Cofburn analogy is used to define the local liquid-vapor interfacial shear that occurs for high-velocity vapor flow across the spherical surface. The results generated for the local dimensionless film thickness and heat transfer characteristics are discussed. Finally, the results developed in the current study are compared with those generated by previous theoretical and experimental results for laminar flow. It is found that the correlation between the two sets of data is quite satisfactory for low-vapor velocity. However, at the higher vapor velocities, the rate of increase of the coefficient with velocity is greater than that associated with laminar theory. It other words, for high-vapor velocity, the onset of turbulence in the condensate causes discrepancies between the two sets of data. Note that the results of the present study may be used to estimate the heat transfer coefficient more accurately than the result of previous laminar studies.