THEORETICAL AND NUMERICAL ANALYSIS ON DISCHARGE COEFFICIENT OF CRITICAL SONIC NOZZLES ISO-9300 WITH TURBULENT BOUNDARY LAYER

摘要

A theoretical and numerical analysis of the discharge coefficient in toroidal sonic nozzles ISO- 9300 with turbulent boundary layer has carried out. This work is focusing on an analytic study of those parameters strike directly on the discharge coefficient determination. Considering the principle of split flow through the nozzle, the analysis was carried out over two regions: one on which the flow is treated with the theory of inviscid flow whereas in the second one the viscous effects are restricted to the boundary layer developed across the axial geometric profile of the nozzle. The flow on first region above is considered as irrotational because there does not exist any interference caused by the boundary layer. In this zone, the flow is a function of the changes on: velocity, pressure and density profiles due to centrifugal forces generated on nozzle curvature. On the other region, turbulent boundary layer is present. So, the characteristic parameters as momentum and displacement thickness appear in this zone, together with shape coefficient, Prandtl number, boundary conditions on nozzle (cool or cold wall) and those due to the nozzle geometry. This analytical model was combined with a numerical formulation using the computational platform available at the Thermal & Applied Hydraulic Engineering Laboratory, National