申論題

一、請將下列英文譯為中文：（25 分） Propeller excitation is far more difficult to quantify than the excitation from internal machinery sources. This is because of the complexity of the unsteady hydrodynamics of the propeller operating in the non-uniform hull wake. In fact, the non-uniform hull wake is the most complicated part; unfortunately it is also the most important part. Propeller- induced vibration would never be considered in ship design if the propeller disk inflow is circumferentially uniform. Any treatment of propeller excitation must begin with consideration of the hull wake.