Experimental Test, Model Validation, and Viability Assessment of a Wave-Rotor Constant-Volume Combustor

Abstract

Design and testing of a wave-rotor constant-volume combustor achieved stable combustion at near-atmospheric inlet conditions and demonstrated the potential of pressure-gain combustion using a wave rotor. An experiment rig with a motor-driven, room-temperature rotor with large thermal mass operated for short durations within heating limits of extensive in-passage rotating instrumentation. Over 30 successful tests were completed, including a 3 s run amounting to about 2000 individual firing events. Fast deflagrative combustion was observed with varied ethylene fuel distribution in the passages, showing good combustor operability, insensitive to leakage. Remarkably high flame speeds and a net pressure gain were indirectly indicated from measurements. A time-marching, spatially one-dimensional numerical model of gas dynamics and combustion was used for aerothermodynamic design, applying loss models previously calibrated with pressure-exchange nonreacting wave-rotor experiments. Major features and trends of the measured gas dynamic and combustion processes showed good agreement with predictions and validated current design methods. Different fuel distributions were tested to better calibrate ignition and combustion submodels. Simulations illustrate the likely explanations for cases with and without observed ignition, spillage during the filling process, and mixture requirements for consistent torch ignition. The viability of wave rotors for realizing a pressure-gain combustor is discussed.