Research On Modeling And Control For Integrated Helicopter/Turboshaft Engine System In Helicopter Autorotation Decent/Recovery Process

To enhance a helicopter’s survivability, autorotation landing training is usually a necessary lessonfor pilots. During an autorotation training process, there are large, rapid changes of rotor loadespecially in autorotation recovery. If the turbo-shaft engines cannot supply torque or power rapidly,these rapid load changes may result in unacceptable rotor transient droop. Therefore, the integratedhelicopter/turboshaft-engine control methods are investigated to solve the problems above.Firstly, an improved nonlinear dynamic model of helicopter/turbo-shaft engines, which cansimulate autorotation decent and autorotation recovery, is presented. In this nonlinear dynamic model,a simplified method is used to calculate the momentum power in autorotation process, and then thetransient variation of rotor speed can be obtained. A turbo-shaft engine Component-Level-Model isbuilt based on volume dynamics theory, and the simulation results show that the component levelmodel is agreed with areo engine theory in the trimmed states and transient process.Secondly, a novel robust twin loop scheme for turbo-shaft engines, including not only fuel flowbut also compressor guided vanes control, is proposed and designed to increase the engine transientresponse and reduce the transient droop of the rotor speed of power turbine. A multi-variable robustH2/H∞controller is proposed based on LMI regional pole assignment algorithm. Two autorotationdecent trajectories are present as simulation cases, and the results show it clear that the rotor transientdroop, controlled by the proposed control law, is more reduced than traditional method onlyemploying fuel flow control, while the dynamic quality of fuel flow is much better. Moreover a robustH2/H∞twin loop scheme including fuel flow and turbine bleed flow, based on LMI algorithm, isdesigned for the same autorotation decent trajectories, and comparisions of the two rubust controlschemes are simulated to show the advantages and disadvantages of two advanced control schemes.At last, according to the large rapid change of fuel flow during the variable rotor speed process, aMulti-input Single-output control scheme for the turbo-shaft engine, including fuel flow andcompressor guided vanes control is proposed and designed, based on ALQR (Augment LinearQuadratic Regulator) algorithm. The simulation results show that the instructions of power turbinerotor speed is asympotically traced, and the dynamic response of fuel flow is much smoother. Furthermore, the total fuel consumption is reduced much more during the variable rotor speed process.