Analysis of the hydrodynamic damping of a hydrofoil with leading edge cavitation using the modal work approach

Abstract

The objective of this investigation is to evaluate the applicability and accuracy of the modal work approach in predicting the hydrodynamic damping of a hydrofoil with leading edge cavitation. Simulations are carried out at a flow velocity of 6.64 m/s, an attack angle of 10°, and cavitation numbers between 1.04 and 2.02. The grid scale, time step, and mode shape amplitude are carefully verified. Results for the cavitation shedding frequencies and hydrofoil natural frequencies show good agreement between experiment and simulation, with relative errors within 8.76% and 7.12%, respectively. The unsteady characteristics of leading edge cavitation have a significant influence on the modal parameters, such as the variation in natural frequency can reach 32.57% in a cavitation cycle and the corresponding mode shape is also changed. Therefore, a new strategy including unsteady mode analysis and energy dissipation signal filtering is proposed to simulate the hydrodynamic damping ratio with leading edge cavitation. Then, the time-averaged hydrodynamic damping ratio in a cavitation cycle is obtained, with relative errors between 15.11% and 35.57% by comparing them with the experimental results. This study realizes the application of the modal work approach in leading edge cavitation conditions.