Predicted combined effects of purge flow and rotor-casing eccentricity on ingress heating

The combined effect of purge/coolant flow rate and nonwhirling, rotor-casin g radial eccentricity on the gas-turbine wheelspace cavity thermal environm ent was determined from a computational study. in this study, a series of R eynolds-averaged, Navier-Stokes numerical experiments was undertaken to obt ain an improved understanding of mass ingress cavity heating. A recently de veloped and heavily tested three-scale k-epsilon turbulence model was utili zed. The temperature, pressure, Mach number, and Reynolds number of a typic al commercial gas-turbine engine were specified as appropriate for the main stream, purge/coolant stream, and turbine wheel. At engine nominal conditio ns, no mass ingress (100% rim seal effectiveness) was found for the concent ric rotor case. However, for 50% rotor-casing eccentricity, large mass ingr ess and only 53% rim seal effectiveness were found, In addition, the minimu m purge flow to prevent mass ingress increased markedly, i.e., from 8000 to 23,500 as the rotor eccentricity increased from 5 to 50%.