The structural vibration and the sound radiation induced by the flow over a cavity on a hydrofoil are investigated experimentally and numerically. The large eddy simulation(LES) is adopted to calculate the flow field ...The structural vibration and the sound radiation induced by the flow over a cavity on a hydrofoil are investigated experimentally and numerically. The large eddy simulation(LES) is adopted to calculate the flow field and the pressure fluctuation characteristics. A coupled finite element method/boundary element method approach is used to analyze the hydrofoil vibration and the structure-borne noise. The flow noise is calculated using an acoustic analogy by considering the surface pressure fluctuations as the dipole sources. A hollow hydrofoil with an orifice supported by four cylinder rods is constructed for the experiments. Modal tests are performed to obtain the natural frequencies of the hydrofoil in air and water. The vibro-acoustic experiments are carried out in the water tunnel at various free stream velocities with the orifice open and closed. A pressure transducer is used to measure the pressure fluctuations behind the downstream edge of the orifice. The triaxial accelerometers mounted on the side walls are used to measure the vibrational response of the hydrofoil. Furthermore, a hydrophone located in a box, filled with water is used to measure the sound radiation. The structure-borne noise and the flow noise are identified by their frequency properties. Reasonable agreements are observed between the numerical predictions and the experimental measurements.展开更多
A numerical model is proposed for analyzing the effects of added mass and damping on the dynamic behaviors of hydrofoils.Strongly coupled fluid-structure interactions(FSIs)of hydrofoils are analyzed by using the 3-D p...A numerical model is proposed for analyzing the effects of added mass and damping on the dynamic behaviors of hydrofoils.Strongly coupled fluid-structure interactions(FSIs)of hydrofoils are analyzed by using the 3-D panel method for the fluid and the finite element method for the hydrofoils.The added mass and damping matrices due to the external fluid of the hydrofoil are asymmetric and computational inefficient.The computational inefficiencies associated with these asymmetric matrices are overcome by using a modal reduction technique,in which the first several wet mode vectors of the hydrofoil are employed in the analysis of the FSI problem.The discretized system of equations of motion for the hydrofoil are solved using the Wilson-6 method.The present methods are validated by comparing the computed results with those obtained from the finite element analysis.It is found that the stationary flow is sufficient for determining the wet modes of the hydrofoil under the condition of single-phase potential flow and without phase change.In the case of relatively large inflow velocity,the added damping of the fluid can significantly affect the structural responses of the hydrofoil.展开更多
文摘The structural vibration and the sound radiation induced by the flow over a cavity on a hydrofoil are investigated experimentally and numerically. The large eddy simulation(LES) is adopted to calculate the flow field and the pressure fluctuation characteristics. A coupled finite element method/boundary element method approach is used to analyze the hydrofoil vibration and the structure-borne noise. The flow noise is calculated using an acoustic analogy by considering the surface pressure fluctuations as the dipole sources. A hollow hydrofoil with an orifice supported by four cylinder rods is constructed for the experiments. Modal tests are performed to obtain the natural frequencies of the hydrofoil in air and water. The vibro-acoustic experiments are carried out in the water tunnel at various free stream velocities with the orifice open and closed. A pressure transducer is used to measure the pressure fluctuations behind the downstream edge of the orifice. The triaxial accelerometers mounted on the side walls are used to measure the vibrational response of the hydrofoil. Furthermore, a hydrophone located in a box, filled with water is used to measure the sound radiation. The structure-borne noise and the flow noise are identified by their frequency properties. Reasonable agreements are observed between the numerical predictions and the experimental measurements.
基金supported by the National Natural Science Foundation of China(Grant Nos.52001130,11922208, 51839005)supported by the Scientific Research Foundation from Huazhong University of Science and Technology(Grant No.2019kfyXJJS005).
文摘A numerical model is proposed for analyzing the effects of added mass and damping on the dynamic behaviors of hydrofoils.Strongly coupled fluid-structure interactions(FSIs)of hydrofoils are analyzed by using the 3-D panel method for the fluid and the finite element method for the hydrofoils.The added mass and damping matrices due to the external fluid of the hydrofoil are asymmetric and computational inefficient.The computational inefficiencies associated with these asymmetric matrices are overcome by using a modal reduction technique,in which the first several wet mode vectors of the hydrofoil are employed in the analysis of the FSI problem.The discretized system of equations of motion for the hydrofoil are solved using the Wilson-6 method.The present methods are validated by comparing the computed results with those obtained from the finite element analysis.It is found that the stationary flow is sufficient for determining the wet modes of the hydrofoil under the condition of single-phase potential flow and without phase change.In the case of relatively large inflow velocity,the added damping of the fluid can significantly affect the structural responses of the hydrofoil.
