AN ADVANCED DILUTION HOLE CONCEPT TO REDUCE PATTERN FACTOR IN GAS TURBINE COMBUSTORS

OF CRITICAL IMPORTANCE IS ADVANCED TECHNOLOGY GAS TURBINE COMBUSTORS IS THE REDUCTION OF EXIT TEMPERATURE NON-UNIFORMITY, COMMONLY KNOWN AS PATTERN FACTOR. A PRINCIPAL CAUSE OF TEMPERATURE NON-UNIFORMITY IS THE LACK OF PENETRATION AND MIXING OF DILUTION AIR IN THE COMBUSTOR DILUTION ZONE. AN ADVANCED DILUTION HOLE CONCEPT IS PROPOSED THAT IMPROVES JET PENETRATION AND MIXING COMPARED TO CONVENTIONAL HOLE DESIGNS. THE CONCEPT EMPLOYS CO-AXIAL JETS; THE OUTER JET IS SWIRLED WHILE THE INNER JET IS NOT. A RADIAL PRESSURE DROP, CAUSED BY OUTER SWIRL, RESULTS IN A PRESSURE DROP ACROSS THE INNER JET MUCH HIGHER THAN THE COMBUSTOR LINER PRESSURE DROP. THE INCREASED PRESSURE DROP IS EXPECTED TO GREATLY ENHANCE PENETRATION AND MIXING OF THE INNER DILUTION JET. PHASE I WILL USE COMPUTATIONAL FLUID DYNAMICS TECHNIQUES TO ANALYZE AND COMPARE CONVENTIONAL AND ADVANCED HOLE DESIGNS. THE TECHNICAL MERIT AND FEASIBILITY OF THE CONCEPT WILL BE VERIFIED OR DISPROVED. IF VERIFIED, PHASE II WILL OPTIMIZE THE CONCEPT AND DEVELOP A DESIGN SYSTEM FOR ITS IMPLEMENTATION. OPTIMUM CONFIGURATIONS WILL BE FABRICATED AND EXPERIMENTALLY TESTED.