Active Vibration Control Of A Conical Nozzle Using Piezoelectric Ceramics

With the characters of high propulsive efficiency,low acoustic radiation and speedy maneuverability,waterjet thrusters are widely used on various kinds of high-performance ships.Vibration noise on waterjet nozzle stimulated by unsteady pressure pulsation of the internal flow field is one of the main noise sources at working condition.The nozzle vibration control is important to suppress the noise of waterjet,which has significant engineering application values.As its excellent frequency response characteristics,high sensitivity,easy cutting and processing,piezoelectric ceramic material can be used on active vibration control research,which is an effective method to suppress the structural vibration noise with the development of vibration control technology.In this paper,the active vibration control of waterjet nozzle was carried out using piezoelectric ceramics,mainly completed the following work:(1)The sensing and actuating equations of piezoelectric ceramics were derived based on materials' electrical mechanics characteristics.(2)Combined with theoretical analysis and existing research results,the pressure fluctuation characteristics of the internal flow field of the waterjet thruster were analyzed,based on which,the simulating signal of nozzle structural vibration was obtained and used as the excitation signal in active vibration control experiment.(3)The modal parameters and vibration mode information of the nozzle structure in air and underwater were obtained using the acoustic-solid coupling finite element method.The effectiveness of numerical simulation method was verified by modal experiments using frequency sweeping test to identify the system parameters of nozzle structure both in air and water.(4)Based on independent modal vibration control strategy,an independent modal fuzzy sliding mode controller with high robustness was designed using the first four-order vibration mode parameters of the nozzle structure.(5)The hardware platform of the vibration active control experiment was prepared using piezoelectric ceramic materials as the sensor and the actuator.The vibration active control software was programed using LabVIEW.The results between experiment and analysis in different mediums were in good agreement,which verified the effectiveness of the vibration control strategy based on selected independent vibration modals.