A nonlinear optimization approach is used to determine the minimum weight design for radiating fin arrays used in space applications. Straight and circular fins of rectangular and triangular profile are considered for emissivities in the range of 0.8 to 1.0. The heat transfer analysis includes fin to fin and fin to base radiative interactions. The results, presented in graphical form, give the optimum geometries for the profiles considered in terms of dimensionless parameters. Thus, for specified values of heat transfer rate, base cylinder surface temperature and thermal properties of the fin material, these curves may be used to design minimum weight fin arrays. Two numerical examples are given.

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A two-dimensional numerical method has been developed to predict heat transfer to near critical fluids in turbulent flow through circular tubes. The analysis is applicable to the thermal entry region as well as fully developed flows. Agreement with experimental data for water at 31.0 MN/m2 is quite good. A correlation in the form of the heat flux parameter of Goldmann was found to be satisfactory for water at that pressure. Results are presented in graphical form which apply to a wide range of heat fluxes, mass velocities, and tube diameters. Preliminary results in the entrance region show that film coefficients remain well above the corresponding fully developed values for a larger distance downstream than would be the case with a constant property fluid. This effect becomes more pronounced as the heat flux is increased.