IN MODERN HIGH PERFORMANCE GAS TURBINES OF INTEREST TO THE AIR FORCE IT HAS BEEN FOUND BENEFICIAL TO ACHIEVE HIGH OPERATING TEMPERATURES AT THE EXPENSE OF REQUIRING ACTIVE COOLING OF MANY OF THE COMPONENTS.

IN MODERN HIGH PERFORMANCE GAS TURBINES OF INTEREST TO THE AIR FORCE IT HAS BEEN FOUND BENEFICIAL TO ACHIEVE HIGH OPERATING TEMPERATURES AT THE EXPENSE OF REQUIRING ACTIVE COOLING OF MANY OF THE COMPONENTS. THIS COOLING AIR IS OFTEN DRAWN FROM THE COMPRESSOR AND FED INTO THE TURBINE ALONG A PATH THROUGH THE INTERIOR OF THE ENGINE OUT OF THE MAIN GAS PATH THROUGH THE COMBUSTOR. EFFICIENCY DEMANDS THAT THE COOLING AIR MASS FLOW AND RESULTING LOSSES, BOTH DIRECT AND INDUCED, BE MINIMIZED. HERE THE PROBLEM OF SUPPLYING THIS COOLING AIR TO THE TURBINE DISCS AD ENDWAL IS ADDRESSED TOGETHER WITH THE COMPANION PROBLEM OF PREVENTING HOT GAS INJESTION INTO DISC CAVITIES, WHILE AT THE SAME TIME DISCHARGING THE COOLING FLOW BACK INTO THE MAIN GAS PATH WITH MINIMAL ADVERSE CONSEQUENCE. AN ANALYTICAL APPROACH IS ADOPTED TO ELUCIDATE THE COMPLEX FLUID MECHANIC PROCESSES OCCURING IN THESE DEVICES, SINCE AT PRESENT THE FLUID MECHANIC PROCESSES ARE POORLY UNDERSTOOD AND POSE A FORMIDABLE EXPERIMENTAL PROBLEM. SINCE THE FLUID MECHANIC PROCESSES ARE SO COMPLEX, THE PROPOSED APPROACH IS BASED ON NUMERICAL SOLUTIONS TO THE COMPRESSIBLE ENSEMBLE AVERAGED NAVIER-STOKES EQUATION. THE GOAL OF THE OVERALL EFFORT IS TO DEVELOP BOTH AN UNDERSTANDING AND APREDICTIVE CAPACITY WHICH WOULD ULTIMATELY IMPACT THE DESIGN PROCESS.