基于直升机综合扭振模型的发动机扭振抑制方法

Engine Vibration Compensation Based on Integrated Torsional Vibration Helicopter Model

关键词:  直升机  发动机  综合扭振模型  扭振抑制

Key words:  Helicopter  Engine  Integrated torsional vibration model  Torsional vibration suppression

摘要:

为了抑制直升机机动飞行时涡轴发动机自由涡轮、燃油调节系统出现的耦合扭振不稳定性，充分考虑了由旋翼、桨毂、传动系统、发动机以及机身组成的扭矩动力传递链的动态响应过程，建立了具有一定置信度的直升机综合扭振模型；并根据扭矩动力传递链特点，设计了作用于发动机转速控制回路的附加相移小的陷波滤波器以抑制综合扭振模型中涡轴发动机扭振。数字仿真表明，所建立的直升机综合扭振模型，在时域中，不同高度、马赫数下均可见低频扭振和高频扭振，与频域计算得到的低阶扭振频率1.92Hz，高阶扭振频率52.52Hz相符。同时，设计的扭振滤波器滤波幅值约-20dB，相角变化在[±]50°范围内，通频带附加相移小，能较为显著地抑制自由涡轮、燃油调节系统耦合扭振。

Abstract:

The coupled instability would be caused by coupled free turbine and fuel regulation system during maneuvering flight. To fully compensate for the instability，the dynamics of torque transmission chain，which includes rotor/ hub/ transmission/ engine and fuselage，is investigated. With analysis of the torque transmission train，a high fidelity，integrated torsional vibration helicopter model is established. Based on that model，a notch filter with small phase shift，which is applied to speed control loop of the engine，is designed to do torsional vibration suppression of the turbo-shaft engine. Digital simulations show that torsional vibration of low and high frequency can both be observed in time domain，when the integrated torsional vibration helicopter model is run at different altitudes and Mach numbers. The vibration data in time domain accords with the low frequency torsional vibration of 1.92Hz and the high one of 52.52Hz in frequency domain. Also，the designed notch filter has a notch magnitude of -20dB. And its phase range covers [±]50°. Small phase shift can be seen in transmission band. Simulations show that vibration suppression characteristic of the coupled free turbine and fuel regulation system is remarkable with the designed filter.