Investigation of Cavitation Phenomena in a "High-Power" Piezohydraulic Pump: A Computational Fluid Dynamics (CFD) Approach

Piezoelectric pumps, known as piezopumps, are highly versatile devices with applications in various fields due to their precise flow control, compact design, lack of magnetic interference, and low noise. These pumps are classified based on the number of pumping chambers, valve configuration, and driving power source mechanism. In fields requiring consistent flow rates and back pressures, particularly in fluid power applications, piezopumps employing a piezostack actuator as their power driving source are actively researched. This kind of piezopumps, also known as piezohydraulic pumps, operate using a piezostack actuator to drive a piston for fluid delivery, along with reed valves controlling fluid flow at the inlet and outlet of the pump chamber. The high operating frequency range of the piezostack actuator and reed valves, exceeding 1 kHz, allows piezohydraulic pumps to achieve significant flow rates despite the stack's limited displacement. This enhances their performance without the need for increased size or power input. However, this also increases the risk of cavitation, which could lead to damage, reduced efficiency, and higher noise levels. Therefore, the purpose of this paper is to expand on previous research by using the CFD software Ansys Fluent to further investigate cavitation phenomena in a piezohydraulic pump developed at the University of Bath. In particular, the study focuses on simulating various oil flow scenarios through the pump with a fixed inlet pressure of 20 bar, while varying the opening of the inlet reed valve from the minimum (0.1 mm) to maximum (0.7 mm) value, as well as adjusting the pump chamber pressure.