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直升机标准桨叶特性参数测量技术研究
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摘要
直升机标准桨叶是直升机批生产桨叶特性参数检测和调试的参照标准,是保存该型号直升机桨叶特性参数的原始标准,是实现直升机桨叶单片互换的基础。桨叶是直升机旋翼升力系统的重要部件,其特性参数直接影响到直升机的飞行品质,每一片批生产桨叶在装机前都要进行动平衡检测和调整,使其特性参数与标准桨叶一致。我国某型号直升机3片标准桨叶由法国引进,复合材料制造,其中1片标准桨叶的特性已发生变化,与原始校准数据和其他2片标准桨叶参数无法对应,已经停止其作为标准桨叶的特性参数传递过程,严重影响了某型直升机批生产桨叶的检测任务,若再有1片标准桨叶特性参数发生变化则会造成很严重的后果,必须对3片标准桨叶的特性参数进行系统调整,使其恢复到出厂时的技术参数水平,保持标准桨叶特性参数长期稳定性和一致性,为标准桨叶的系统校准奠定基础。
     本文把标准桨叶动平衡过程中桨叶挥舞角按Taylor基数展开,建立了标准桨叶带复杂空气动力激扰的Duffing非线性挥舞运动方程,通过Melnikov方法分析了桨叶所受气动力、气动阻尼、2倍和3倍周期不平衡空气动力激扰作用对挥舞方程稳定性和标准桨叶挥舞参数的影响,得出标准桨叶挥舞参数是稳定的,但对旋翼桨毂特性和试验环境参数比较敏感。
     桨叶挥舞高度参数受到标准桨叶本身特性参数和其他试验参数的影响,通过在动平衡试验台上交换标准桨叶安装位置的方法,获得标准桨叶的动平衡试验参数,实现标准桨叶特性参数与旋翼桨毂参数的解耦。根据标准桨叶动平衡和标准传递过程,确定标准桨叶需要测量和调整的静态特性参数和动态特性参数;针对标准桨叶挥舞运动对环境阵风引起的不平衡空气动力的挥舞响应,文中提出了桨叶动平衡试验环境中风速影响的分析方法,通过仿真试验和实际测量数据,得出了在桨叶挥舞参数误差要求范围内的风速极值,结果与法国相关的试验标准相吻合,进而确定了标准桨叶特性参数测量与调整过程的环境风速条件,奠定了准确恢复标准桨叶特性参数的基础。
     本文采用激光测量技术来测量桨叶的挥舞参数。进一步研究了激光器安装定位参数的测量方法,利用激光器本身的结构和标定算法,实现了激光器定位参数的标定;利用一定厚度的模拟桨叶切割激光光路的方法标定标准桨叶挥舞参数测量系统,实现了标准桨叶挥舞参数测量系统的标定和溯源。最后,对标准桨叶挥舞参数测量系统和测量结果进行了不确定度分析。
     对于标准桨叶铰链力矩的测量,文中设计了基于RBF神经网络的铰链力矩载荷识别和动态特性补偿方法,神经网络的结构避免了建立系统的结构模型,把扭矩载荷识别和标定的反问题都做为正问题处理。用同步采样的实际静态载荷和正弦扭矩载荷数据训练神经网络,并对训练结果进行了试验数据验证,实现了铰链力矩测量系统的动态标定,提高了标准桨叶铰链力矩的测量准确度。
     本文针对某型号标准桨叶静态特性参数和动态特性参数进行了具体的试验测量,通过实测数据与法国出厂校准数据的比较,找出了标准桨叶特性参数变化的趋势,提出了标准桨叶特性参数整体调整恢复的方法,使标准桨叶特性参数恢复到出厂时的参数水平,保证了标准桨叶特性参数的延续性和长期稳定性。
The primary standard blade is the reference standard of natural parameters for work rotor blades on measurement and adjustment process, the transmission standard for batch productions, as well as the base of interchangeability for single rotor blade. The rotor blades are the important parts that determinate the flight quality of helicopters. Each piece of rotor blades must be measured and adjusted on a dynamic balance tester in order to make the parameters uniform as the primary standard blade before the final assembly. The three pieces of primary standard rotor blades in our country are made in France with the composite material, the natural parameters of one piece of standard blades have been changed, parameters in which disagree with the original data and other two standard blades. Once a standard rotor blade stops work, it will have a strong impact on the other types of helicopter rotor blades. The result is extremely serious if the other standard blade parameters are changed. The primary mission is to calibrate and adjust the standard rotor blade parameters, and recover its original parameters in order to keep the long-time stability and uniformity.
     With the dynamic balance testing process, a method is proposed by deriving the flapping equation, expanding the flapping angle by the method of Taylor radix and building the nonlinear Duffing’s flapping equation with complex aerodynamics perturbation for the primary standard rotor blade. The stability of flapping equation with the action of aerodynamics, aerodynamic damping, double-period and triple-period aerodynamics perturbation are analyzed with Melnikov method. The result is that the rotor flapping is stable on flapping equation and sensitive on testing environment.
     The flapping parameters are impacted by the natural parameters of standard rotor blade and other testing parameters. Using the method of changing the installation position on rotor hub, the testing parameters of standard rotor blades are obtained and the standard rotor blade parameters from hub parameters are uncoupled. The gust can influence the results of dynamic parameters for the primary standard rotor blade, an analysis method with wind speed in a dynamic balance testing environment is proposed for the flapping response by non-balance aerodynamics perturbation caused by gust, the extreme value of wind speed in the dynamic balance testing is determined by the emulator program and actual data, the result is the same as the French testing standard. The wind speed in the process of calibration is determined for primary standard rotor blade, and the base of parameters recovery process is settled.
     With the measurement technique of laser, a method is proposed to measure the flapping parameters of primary standard rotor blades,and a further design of measurement method is applied in calibrating the spatial location parameters of laser. At the same time, a method is proposed to calibrate the flapping measurement system with a definite thickness simulator as blade and the measurement system is calibrated. Finally, the uncertainty of measurement system and flapping parameter are analyzed.
     For the measurement of flapping hinge moment, a recognition method for load and compensation on a dynamic characteristic is proposed based on RBF neural network, this method avoids to build the mathematical model for the measurement system, and inverts the indirect problem of recognition process and calibration process into a direct problem. To train and check the networks with the synchronous sampling data of sine torque moment, the hinge moment measurement system is calibrated dynamically, and the measurement uncertainty is improved in flapping hinge moment for primary standard rotor blade.
     For the actual data of static parameters and dynamic parameters of some primary standard rotor blade, a calibration and adjustment method is proposed by comparing the actual data with data from France. With the calibration and adjustment process, the parameters of primary standard rotor blades resume the initial state. This proposed method guarantees the long-time stability of natural parameters for the primary standard rotor blades.
引文
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