CHARACTERIZATION OF FLAMHOLDER BLOWOUT IN GAS TURBINE AUGMENTORS

GAS TURBINE AUGMENTORS HAVE HISTORICALLY EXPERIENCED DIFFICULT MAINTAINING COMBUSTION AT HIGH ALTITUDES AND LOW FLIGHT MACH NUMBERS. DUE TO THE LACK OF ANALYTICAL TOOLS, TESTING PROVIDES THE PRINCIAL MEANS OF IMPROVING A DESIGN FOR STABILITY. SUCH TESTING IS EXPENSIVE AND TIME CONSUMING, THUS ALLOWING ONLY A LIMITED NUMBER OF DESIGNS TO BE ASSESSED. WHAT IS LACKING IS A GOOD UNDERSTANDING OF THE FLOW CHARACTERISTICS THAT CAUSE FLAMEHOLDER BLOWOUT. THIS PROJECT PROPOSES TO USE AN EXISTING COMPUTATIONAL FLUID DYNAMICS (CFD) CODE TO ANALYZE THE BLOWOUT PHENOMENA IN A CONFINED DUCT WITH A CHOKED NOZZLE. THE CFD CODE WILL SOLVE THE TIME-DEPENDENT, COMPRESSIBLE NAVIER-STOKES EQUATIONS TO PREDICT LARGE SCALE EDDIES SHED FROM THE FLAMEHOLDER AND LONGITUDINAL/RADIAL ACOUSTIC WAVES GENERATED BY THE COMBUSTION PROCESS. THE FOCUS IN PHASE I WILL BE ON SHOWING THE VIABILITY OF USING LARGE EDDY SIMULATIO (LES) TO CAPTURE THE INTERACTION OF VORTEX SHEDDING, CHEMICAL REACTION, AND ACOUSTIC WAVES AT BLOWOUT. THE BLOWOUT SIMULATION WILL BE VALIDATED IN PHASE II, AND THEN USED TO PERFORM PARAMETRIC STUDIES ON ADVANCED FLAMEHOLDER SHAPES SUCH AS THE INTEGRAL SPRAYBAR/FLAMEHOLDER. THE FINDINGS WILL CULMINATE IN A CHARACTERIZATION AND DESIGN TECHNOLOGY FOR IMPROVING AUGMENTOR STABILITY.