A Quasi-Analytical Method for Fluid Flow in a Multi-Inlet Collection Manifold

Abstract

This paper sets forth a fully validated quasianalytical method for determining the fluid flow in a multi-inlet collection manifold. The method is based on first principles, which are the conservation laws for mass and momentum. Although it is necessary to use numerical means to extract results from the model, the solution task is accomplished by the use of a spreadsheet, without the need for complex software or large computer assets. The validation of the method was achieved by comparing the key results with those from a numerically exact simulation. The comparison included both local results and global results. For the local results, the accuracy of the model was found to be in the 1% range, while the global results from the model were accurate to about 4%. The investigated manifold was a case study drawn from a problem involving thermal management of electronic equipment, in which an array of coldplates discharged spent air into the manifold. It was found, from both the quasianalytical method and the numerical simulation, that there is a variation in the per-coldplate flowrate due to axial pressure variations in the manifold. These pressure variations can be attributed to the streamwise acceleration of the manifold flow due to the accumulation of the flow entering the manifold from the coldplate array. The utility of the quasianalytical method was further demonstrated by applying it to a number of other cases. In particular, the method was used to design a manifold capable of producing a uniform mass flowrate through all of its ports.