Propeller Synchrophasing Control with a Cylindrical Scaled Fuselage Based on an Improved Data Selection Algorithm

Abstract

Propeller synchrophasing control is an active noise control method which can effectively reduce the noise in the cabin of a turboprop aircraft. The propeller signature model identified by the measured acoustic noise data is easily affected by flight speed, altitude, and the existence of the fuselage. Meanwhile, the noise excited by the propellers is nonstationary signal, which often fluctuates greatly, thus affecting the accuracy of the identification of the model. In this paper, a synchrophasing control experimental platform with a cylindrical scaled fuselage on ground is firstly established to validate the actual noise reduction in the cabin. Then, a minimum fluctuation data selection method based on wavelet filtering and three-parameter sinusoidal fitting is proposed to improve the identification accuracy of the propeller signature model. This method extracts the high-precision propeller blade passing frequency signal from the noise signal by using a wavelet filtering algorithm and selects the minimum fluctuation data segment by using a three-parameter sinusoidal fitting algorithm. The experimental results firstly show the significant noise attenuation achieved in the cabin using propeller synchrophasing control. Secondly, the propeller signature model improved by the minimum fluctuation data selection method has higher accuracy than that identified by the traditional method.Energies 2019, 12, 2736 2 of 17 of a multipropeller aircraft, so that part of the rotating noise and vibration generated by each propeller cancel each other out, and the cabin noise is minimized.Blunt et al.[5] carried out synchrophasing control experiments in a real flight on C-130J-30 and AP-3C. Obviously, the cost of the real flight is huge and the experiments are time-consuming, meaning they are not be suitable for further research on propeller synchrophasing control. Huang et al. [6] and Sheng et al.[7] established a ground experimental platform to study the effectiveness of synchrophasing control and significant noise reduction was achieved. However, the existence of the fuselage is an inevitable factor that can affect the performance of the synchrophasing control, and is difficult to analyze due to the complex acoustic vibration couplings between the fuselage and the enclosed cabin space. Investigation needs to be made to explore the real performance of the synchrophasing control inside the cabin in the presence of the fuselage in a relative low-cost way.Noise modeling is the key issue to achieve significant noise reduction. Experimental and analytical works on the problem of noise modeling have been carried out by several researchers [8]. Atassi et al. [9] determined that the fluctuating loads resulted from ingested turbulence from blade to blade. Ground vortex ingestion was considered in the noise modeling in stationary or near-stationary aircraft engines by Murphy et al. [10]. Stephens et al. [11] studied casing boundary layer/rotor interaction and unsteady blade loading, and the radiated sound was determined by strip theory, whe...