FILM AND TRANSPIRATION COOLING OF NOZZLE THROATS

The following conclusions were drawn 1 Gas film cooling can be used to measurably lower the wall temperatures and the wall heat fluxes in the converging section and at the throat of a high-pressure high-temperature nozzle. Some gross mixing occurs at the injection point, the exact amount being some as yet undetermined function of the injection geometry, the relative velocities of the main gas stream and the coolant stream at the injection point, and the entering velocity profiles and turbulence conditions. 2 A straightforward boundary layer type analysis was developed and programmed which predicts with reasonable accuracy the nozzle wall temperatures and wall heat fluxes in the converging section and at the throat for gas film cooled nozzles. 3 Calculational techniques were developed and programmed for predicting the effectiveness of liquid film cooling and liquid or gas transpiration cooling in nozzles. These techniques should be checked against experimental data before they are used for design purposes, however.