Transient Three-Dimensional Side-Load Analysis of Out-of-Round Film-Cooled Nozzles

摘要

The objective of this study was to investigate the effect of nozzle out-of-roundness on the nozzle side loadsngenerated during an engine start transient. The out-of-roundness could be the result of asymmetric loads induced bynhardware attached to the nozzle, asymmetric internal stresses, and deformation induced by previous tests. Thenrocket engine studied encompasses a regeneratively cooled chamber and nozzle, along with a film-cooled nozzlenextension. The computational methodology is based on an unstructured-grid, pressure-based computational fluidndynamics formulation and transient inlet boundary conditions from an engine system simulation. Computationsnwere performed for engine startup with the out-of-roundness achieved by four different degrees of ovalization: onenperfectly round, one slightly out-of-round, one more out-of-round, and one significantly out-of-round. The resultsnshow that the separation-line jump was the source of the peak side load for the first three configurations, with thenpeak side load increasing as the degree of out-of-roundness increased. For the significantly-out-of-round nozzle, thenpeak side loadwas reduced to a level comparablewith that of the round nozzle, due to a splitting of the separation-linenjump.