Detailed measurements of pressure distributions, mean velocity profiles and Reynolds stresses were made in the thick axisymmetric turbulent boundary layer near the tail of a body of revolution. The results indicate a number of important differences between the behaviour of a thick and a thin boundary layer. The thick boundary layer is characterized by significant variations in static pressure across it and an abnormally low level of turbulence. The staticpressure variation is associated with a strong interaction between the boundary layer and the potential flow outside it, while the changes in the turbulence structure appear to be a consequence of the transverse surface curvature. In order to predict the behaviour of the flow in the tail region of a body ofrevolution it is not therefore possible to use conventional thin-boundary-layer calculation procedures.

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An important parameter in the hydraulic design of refrigeration and air-conditioning systems is the two-phase flow pressure drop. In this paper, the authors compare the numerical results obtained by using seven two-phase pressure-drop models with the experimental results found in the scientific literature, for the condensation of R600a and R717 (Ammonia = NH3) in horizontal tubes. Different mass flow rates and different conditions have been considered in order to see which correlation is applicable under specific operation conditions.

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