Control strategy for turbo-shaft engine with Inter-stage Turbine Burner

This paper presents that Inter-stage Turbine Burner (ITB) has a significant potential for increasing specific power of a turbo-shaft engine. The control target is to maximize turbine output power similar to afterburning control scheme for jet engines keeping gas generator working normal. In order to realize the control target, firstly, a component-level model is built up that has ability to simulate both steady and transient states of a turbo-shaft engine with ITB. Secondly, a two-loop control scheme is proposed to solve the problem of turbo-shaft engine afterburning. The objective of first loop under different rotor loads, is to adjust the main burner fuel flow rate for a constant power turbine rotor speed. The second loop is according to different ITB fuel flow rates, to regulate power turbine guide area in order to keep the gas generator normal. Finally, a double closed-loop simulation is performed to test and verify the results of the proposed two-loop control scheme for a turbo-shaft engine with ITB. Simulation results show that the proposed two-loop control strategy leads successfully to increased power of the turbo-shaft engine without disturbing the engine gas generator working. During the period of turbo-shaft engine ITB switching control, the transient time is not more than two seconds, and drop in power turbine rotor speed is less than two percent.