AN EXPERIMENTAL INVESTIGATION OF THE PRESSURE DISTRIBUTION OF AIR IN RADIAL FLOW IN THIN FILMS BETWEEN PARALLEL PLATES

An experimental investigation of the pressure distribution of air in radial flow between parallel plates was conducted. Data were collected on the pressure distribution, mass rate of flow of air and film thickness. Variations were made in the load applied to the upper plate, stagnation pressure at the air supply hole, and the upper plate geometry. Two upper plates having the same outside diameters but different supply hole diameters were employed. Two flow regimes were defined, that where the flow of air is dominated by the viscous forces wherein the pressure decreases steadily from the supply hole to the outer edge of the upper plate and that where the inertia forces predominate and the flow becomes supersonic near the air supply hole. In this latter regime, it was found that the mass flow can be predicted by the theoretic choked flow through the cylindrical area defined by the film thickness and the diameter of the air supply hole.