In this paper analytical expressions for time-dependent velocity profiles and pressure gradient are obtained for fully-developed laminar flows with given volume flow-rate conditions in circular pipe flows with slip boundary conditions. The governing equations are solved analytically using the traditional Laplace transform method together with Mellin's inversion formula. The evolution of velocity profiles and pressure gradient for starting and pulsatile flow with slip boundary conditions are analyzed. New simplified expressions and perspectives on velocity and pressure gradient for no-slip and slip flows are obtained from the analytical results. New scalings in starting and pulsatile flows are proposed for pipe flows with no-slip and slip boundary conditions using nondimensional numbers. Special attention is paid to the effect of slip factor and pulsatile flow frequency on the time-dependent skin-friction factor. Finally, by using the starting and pulsating flow results, analytical expressions of velocity and pressure for arbitrary inflow are obtained by approximating the arbitrary volume flow-rate by a Fourier series
Fluid-pumped radiators are widely used to dissipate thermal load from orbiting space capsules to maintain the desired temperature range. Fluid circulated through the heat generating systems are pumped through the space radiator, which in turn dissipates energy to deep space. Based on the flow path, radiators are classified into series and parallel radiator configurations. As part of realizing radiators for future space missions, experimental studies are carried out in a thermovac chamber to assess the thermal and hydraulic performances of space radiators and compare them for different configurations and working fluids. The paper details the experimental schematics for the different studies, the results of the experiments, and their validation. Series radiator configuration is found to have better thermal performance but lower hydraulic performance compared to parallel radiator configuration. Working fluids with higher specific heat are found to give better thermal performance. A configuration that gives optimum performance in terms of thermal performance and pumping power is evolved based on the studies.
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