20.船舶軸系，是指從主機輸出端的法蘭開始到那裡為止？ (A)螺旋槳 (B)艉軸 (C)中間軸 (D)推力軸

10.Longitudinal vibration of propulsion shafting systems is often excited by the variable thrust developed by the propeller due to the non-uniform wake pattern in which it operates. The predominant periodic component of the thrust developed by a propeller occurs at blade-rate frequency, i.e., the number of propeller blades times the rotational frequency of the shaft. For a four-blade propeller running at 60 rev/min, what is the predominant periodic frequency that excites the longitudinal vibration of the propulsion shafting systems? (A)1 Hz (B)2 Hz (C)3 Hz (D)4 Hz

20.船舶軸系，是指從主機輸出端的法蘭開始到那裡為止？
(A)螺旋槳
(B)艉軸
(C)中間軸
(D)推力軸

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