Effect of Coolant Flow Distribution on Transient Side-Load of Film Cooled Nozzles

Abstract

The objective of this study was to investigate the effect of film coolant distribution on nozzle side loads generated during an engine start transient. The rocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film cooled nozzle extension. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation, and transient inlet boundary conditions calculated from an engine system simulation. Computations were performed for engine startup with two turbine exhaust manifold geometries that produce two different distributions of film coolant mass flow: one with a higher mass flow deviation, while the other has a near uniform distribution. The results show that the configuration with the higher mass flow deviation produced a higher peak side load, manifested by the biased turbine exhaust gas pumping of the supersonic jet of the Mach disk flow; while the configuration with the more uniform coolant flow distribution maintained a more symmetric Mach disk flow throughout the filling process, resulting in a lower peak side load.