Study On Noise Control Of The Electrically Controlled Rotor Based On Non-harmonic Control

Blade-vortex interaction(BVI)noise becomes the main component of the helicopter rotor noise once it appears.The rotor control of Electrically Controlled Rotor(ECR)is realized by the deflection of servo-flap mounted on the back edge of the blade.Its unique structure enables that the BVI noise can be controlled by active methods.The non-harmonic individual blade control(IBC)method allows to apply arbitrary control waveform in any azimuth range required.In this paper,the non-harmonic IBC method for the BVI noise control of the ECR is studied.The main contents are as follows:(1)First,the BVI noise calculation model of the ECR is established through combining the aerodynamics model of the ECR and the FW-H noise equation.Taking the above model as the core of calculation,an optimal analysis model for active control of BVI noise is established.It contains two groups of combinatorial optimization algorithms,which are the multi-island genetic algorithm with sequential quadratic programming and adaptive simulated annealing algorithm with sequential quadratic programming.(2)With the control of BVI noise as the optimization target,the harmonic active control method is studied through simulation analysis.Taking it as a reference,the effects of five different waveforms on BVI noise are studied in the localized azimuth,which are harmonic,step,slope-square wave-slope,harmonic-square wave-harmonic and fitting curve control waveforms.A non-harmonic active control method for BVI noise control of ECR is proposed,and its optimization design is carried out.The simulation results are as follows.For the sample ECR,2Ω is the most suitable to control BVI noise in all control frequencies of the harmonic IBC methods.And in the localized azimuth range with the center of the second quadrant,the effect of the optimized harmonic-square wave-harmonic and the conic curve fitting waveforms on BVI noise is close to the best control effect of the all paddle disc harmonic active control method,when non-harmonic methods are used for control.(3)Based on the simulation results,a wind tunnel test for active control of BVI noise of ECR is carried out.A sweeping study of the control parameters for the harmonic active control \ nonharmonic active control method is carried out.The results are as follows.The control law of harmonic and non-harmonic active control on the peak BVI noise of the front edge of the rotor is similar,and the trend is basically the same.