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直升机旋翼桨毂振动载荷与桨叶动态失速控制

Control of Helicopter Rotor Hub Vibration Load and Blade Dynamic Stall

【作者】 王荣

【导师】 夏品奇;

【作者基本信息】 南京航空航天大学 , 飞行器设计, 2012, 博士

【摘要】 在旋翼桨叶后缘加装小翼是一种有潜力的直升机智能旋翼。通过控制后缘小翼运动优化桨叶气动载荷在桨盘不同方位角和沿桨叶展长上的分布,可提升旋翼及直升机的性能。本文研究了后缘小翼对直升机旋翼桨毂振动载荷和后行桨叶动态失速的控制,具有重要的理论意义和应用价值。本文以4片桨叶的无铰式旋翼为研究对象,采用弹性桨叶和刚性后缘小翼建立结构动力学模型,桨叶剖面气动载荷采用Leishman-Beddoes二维非定常动态失速模型,后缘小翼剖面气动载荷采用Hariharan-Leishman二维亚音速非定常模型,在直升机稳态飞行状态下,建立了用于求解桨叶带后缘小翼的旋翼气弹响应的分析计算模型。本文建立了桨叶后缘单小翼用于桨毂振动载荷控制的分析方法,研究结果表明,桨叶后缘小翼的可控摆动角度对桨毂振动载荷产生显著的影响,采用改进的控制算法对4Ω的桨毂振动载荷进行了优化。对于稳态前飞的直升机,桨叶后缘小翼只需小角度(<3°)的正弦摆动即可有效地影响旋翼桨毂振动载荷,随着小翼摆动相位差的变化,桨毂振动载荷的幅值呈弦线变化,变化趋势与飞行测量的结果一致。不同频率、幅值的小翼摆动对各方向的桨毂振动载荷都具有不同的影响。通过后缘小翼正弦运动状态下获得的桨毂振动载荷分量幅值与小翼摆动参数之间的关系,建立了桨毂振动载荷主动控制算法所需的传递函数。受控的后缘小翼可以有效地控制4Ω的桨毂振动载荷的六个分量。本文建立了桨叶后缘单小翼用于后行桨叶动态失速控制的分析方法,研究结果表明,合理控制桨叶后缘小翼的摆动可以有效地缓解高速、高载飞行条件下后行桨叶的动态失速。在高速、高载飞行条件下,给出了后行桨叶发生动态失速的桨盘区域和相应桨叶段的气动载荷方位角历程。利用单片后缘小翼的正弦运动,平衡桨盘上前、后行桨叶的气动载荷,延迟高速、高载稳态飞行状态下后行桨叶动态失速的发生,减小桨叶上的突变载荷。本文结合后缘小翼对后行桨叶动态失速和桨毂振动载荷的控制效果,在桨叶后缘布置三片小翼,优化两种不同的小翼运动规律,同时控制后行桨叶动态失速和桨毂振动载荷,取得了较好的控制效果。本文对双晶片梁式压电驱动器和小翼组成的驱动系统进行了模型实验,建立了一种小翼共振驱动方法。梁式驱动器采用压电材料制造,通过激发驱动系统共振,使桨叶后缘小翼获得了较大的摆动角度。

【Abstract】 Adding the trailing edge flap in the rotor blade is a potential helicopter intelligent rotor. Theperformance of the rotor and helicopter can be improved by optimizing the distribution ofaerodynamic load through the controlled motion of trailing edge flap in the azimuth of rotor disc andalong the blade span. In this thesis, the control of helicopter rotor hub vibration loads and retreatingblade dynamic stall by using trailing edge flap has been investigated, which has important theoreticalsignificance and application value.In this thesis, a four-bladed hingeless rotor was studied, adopting the dynamic model of an elasticblade with stiff trailing edge flap, using the Leishman-Beddoes unsteady two-dimensional dynamicstall model for calculation of the aerodynamic loads of blade section and using theHariharan-Leishman unsteady two-dimensional subsonic model for calculation of the aerodynamicloads of the trailing edge flap section. In steady flight condition, a computational analytical modelwas established for solving the aeroelastic responses of rotor with trailing edge flaps.In this thesis, an analytical model for control of rotor hub vibration loads by using single trailingedge flap was established. The analytical results indicated that the controlled swing angle of trailingedge flap had the significant influence on the rotor hub vibration loads. The4vibration loads couldbe optimized by using an improved control algorithm. In steady flight condition, the sinusoidal swingof trailing edge flap with a small amplitude (<3°) could effectively affect the rotor hub vibration loads.The hub vibration loads amplitude changed in the form of sinusoid with the phase difference of theflap swing. The changing trends were consistent with the flight testing results. The flap swing withdifferent frequency and amplitude had different effects on each component of the hub vibration loads.Using the relationship between the rotor hub vibration loads components and the swing parameters oftrailing edge flap obtained in the condition of sinusoidal swing of the flap, the transfer functionrequired for active control algorithm was established. All six components of the4vibration loadsrotor hub vibration loads could be effectively controlled by the control of trailing edge flap.In this thesis, an analytical model for control of retreating blade dynamic stall by using singletrailing edge flap was established. The analytical results indicated that the reasonable controlled swingof the flap could effectively alleviate the dynamic stall of retreating blade in the high speed and highload flight condition. The dynamic stall occurring area on the rotor disc and the azimuth-historyresponse of aerodynamic loads on corresponding section of blade are given in the flight condition.The sinusoidal swing of single trailing edge flap could balance the aerodynamic loads on advancing and retreating side of the rotor disk and could delay the occurring of dynamic stall on retreating blade.Combining control effect of rotor hub vibration loads and retreating blade dynamic stall by trailingedge flap, three trailing edge flaps were installed in the blade and two laws of flap motion wereoptimized to control the dynamic stall and the vibration loads at the same time.In this thesis, a model experiment of driven system composed of trailing edge flap andpiezoelectric bimorph beam was conducted to establish a resonance driving method for trailing edgeflap. The beam actuator was made of piezoelectric material. A larger angle of trailing edge flap wasobtained through exciting system resonance.

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