Research On Measurement Technique Of Characteristic Parameters For Helicopter Standard Rotor Blade

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.