Fluid wave actuator for the active control of hydraulic pulsations in piping systems

Fluid-borne vibrations in piping systems remain a serious problem in applications such as marine vessels where mechanical fatigue and radiated noise are critical factors. In the case of pumps or hydraulic engines, the main source of vibrational energy is in the fluid axisymmetric plane wave associated with the system pressure pulsations. Due to fluid/structure coupling, this wave propagates in both the pipe wall and fluid. For high levels of pressure pulsations, the resulting radial and axial wall motion can then cause mechanical fatigue and unwanted radiated noise. Passive pulsations dampers have been used traditionally to reduce the fluid pressure pulses. The use of such passive devices is limited however in critical applications due to the resulting static pressure loss which decreases the system performance. This paper describes the design and testing of a non-intrusive fluid wave actuator for the active control of pressure pulses. The actuator consists of a circumferential ring of PZT stacks acting on the pipe outside wall to generate an axisymmetric plane wave in the fluid. Experimental results estimate the control performance of the actuator applied to the discharge line of an oil driven hydraulic engine.