Advanced Turboshaft Engine/Drivetrain Modeling Technique for Real Time Rotorcraft Simulation

Modeling turboshaft engine and drivetrain dynamics is a vital part of modern rotorcraft simulation as they are closely coupled with the main/tail rotor dynamics and impact the aircraft performance and transient response.The current engine models for real time simulation are mostly custom built and based on the table look-up of the engine steady state performance map. The map lookup solution is not only limited by the availability of empirical engine performance data, but also suffers from an inaccuracy in modeling the engine transient states. For drivetrain dynamics, a single rotational degree of freedom (DOF) for a rigid shaft is typically utilized. In reality, the rotorcraft drivetrain dynamics includes multiple DOFs including elastic torsion. Even for a conventional single main rotor configuration, there are main gearbox dynamics and a tail rotor drive system which have distinct frequencies and transient characteristics. This proposal aims to develop a first principle based engine and drivetrain dynamics modeling method that will reflect rotorcraft propulsion system physics and, hence, provide an accurate physics-based solution. The proposed solution will be analytically formulated and applicable for generic turboshaft engine and drivetrain modeling. The high fidelity method developed will also be evaluated and tested in an industry standard rotorcraft modeling and simulation program to support real time flight simulation.