Steady- and transient-state numerical simulation of turboprop engine of propeller-free-turbine types

In order to simulate the performance of an integral turboprop propulsion system by a mathematics model, the propeller was taken as one of the internal flow components of the turboprop engine greatly influenced by external flow under the flight conditions. With introduction of propeller map and an imaginary mass method, this component-level turboprop engine mathematics model balanced two mass flow rates and powers of the propeller-free-turbine rotor and gas generator. The corresponding code was developed, and the steady- and transient-state sea-level rotational speed characteristics and flight mission profile characteristics of an 8 MW propfan propulsion system were simulated. The numerical simulation results show that, this mathematics model can successfully simulate the detailed performance of the variable pitch angle and the angle of attack of propeller or propfan on the cooperating points, and also the steady- and transient-state characteristics including the thrust and the specific fuel consumption of thrust of turboprop engine, while the environmental and adjusted parameters like altitude, velocity and turbine inlet total temperature are varying.