The use of an inter-turbine burner for improving the part power performance of small turboshaft engines in proposed. An inter-turbine burner is a second combustor placed between the gas generator exit and the power turbine to "reheat" the engine gas stream before it enters the power turbine. The inter-turbine burner is used to increase engine power at the maximum power setting permitting the core engine to be run closer to its design condition at part power settings. Cycle analysis shows significant improvement in engine power with an accompanying increase in specific fuel consumption at the full power condition. The part power specific fuel consumption improves by significant at power levels below half of the maximum power. This improve specific fuel consumption at part power settings will reduce fuel consumption during the cruise/loiter segments of the UAV mission. Thus there is a net benefit to time-on-station, provided that the cruise/loiter segment is long compared to the take-off and climb segments. The increased specific thrust of the turboshaft engine with an inter-turbine burner results in a lighter engine for the same maximum power.
Benefits: The commercial application of the proposed ITB engine technology is a new class of cycles for industrial, marine, and aircraft gas turbine engines. Attractive applications of the proposed technology include both military and commercial turbofan, turboshaft, and turboprop engines and auxiliary power units. Additionally, stationary industrial gas turbine engines, marine gas turbines and other large gas turbine engines may benefit from the proposed technology through improvements in part power performance.
Keywords: Inter-Turbine Burner, gas generator, power turbine, turboshaft, specific power, specific fuel efficiency, re-heat, turbofan
