Minimum Coolant and Resulting Cavity Temperatures for Eccentric Rim Seals With a Mainstream

A 3-D Navier-Stokes computer model, which was previously experimentally verified, was used to explore eccentricity effects on the minimum required coolant flow to prevent ingress (C_w,min) and blade root/retainer temperature. A recently developed three-scale k-ϵ turbulence model was experimentally verified and utilized in the computations. The temperature, pressure, Mach number and Reynolds number of a typical commercial gas turbine engine were specified for the mainstream, coolant stream and turbine wheel. It was found that C_w,min increases markedly with rotor eccentricity, even for small eccentricity values, in an almost linear fashion. The computations were used to establish a correlation for the dependence of C_w,min on eccentricity. It was found, for example, that an eccentricity increase from 5% to only 12.5% of the rim seal clearance increases C_w,min from approximately 8000 to 11000. In addition, for 25% eccentricity, the highest blade root/retainer temperature for C_w = 3600 is 49% higher than that for C_w = 7200, whereas for 12.5% eccentricity, it is only 20% higher.