Evaluation of Pressure Gain and Turbine Inlet Conditions in a Pulse Combustion Gas Turbine

This study investigates the pressure gain and its improvement on the gas turbine performance. The combustor is comprised from two combustion chambers. One chamber A conducts pulse combustion and the other chamber B conducts continuous, constant-pressure combustion. The burned gases of each chamber are mixed and enter the turbine. The detail time variation of chamber pressure as well as turbine inlet and compressor outlet under the pulse combustion mode were experimentally investigated. The pulse combustion in the chamber A generated the pressure wave that propagated not only downstream to the turbine inlet but also chamber upstream. This pressure wave stagnated the gas flow from the compressor in the chamber A. The gas flow velocities at the chamber inlet and outlet of chamber A were measured. The results showed the large velocity variation in one cycle under the pulse combustion mode. Based on the velocity, the cycle-averaged pressures in the chamber A were evaluated by mass-averaging method. The estimated cycle-averaged pressure ratio became 1.067 means that a pressure gain of 6.7% was obtained in the chamber A. Although the hydrogen fuel mass flow rate in the pulse combustion mode was larger than that in the normal combustion mode, the apparent higher value of specific output power in the pulse combustion mode than in the normal combustion mode demonstrated the feature of pressure-gain combustion.