27.27. Diesel engines of conventional design fall into either a low-speed category or the medium and high-speed category. Low speed engines are generally intended for the direct drive of ship’s propellers without any speed-changing device and are restricted to an rpm range for which efficient propellers can be designed. Based on this description, which statement is correct?
(A) A low-speed engine has to consider its speed range in order to match with the propeller design.
(B) The design of efficient propellers is not related with the speed range of low-speed diesel engines.
(C) The speed-changing device is required for a low-speed engine.
(D) The low-speed engine could always provide efficient propulsion without consideration of its speed range.
28.28. Which machinery is used to provide the electrical power required in a ship?
(A) Prime mover
(D) Panel board
29.29. For a seawater cooled condenser in a steam turbine power plant, which is the correct statement regarding the seawater temperature and the performances of condenser?
(A) Low seawater temperature permits high vacuum of condenser.
(B) Low seawater temperature permits high steam saturated temperature in condenser.
(C) Low seawater temperature permits high steam dryness in condenser.
(D) High seawater temperature permits high moisture rate of steam in condenser.
30.30. Which type of bearing may be lubricated by seawater in a main propulsion shafting system?
(A) Thrust bearing
(B) Ball bearing
(C) Crosshead bearing
(D) Stern bearing
31.31. All tanks should be provided with a means of determining the liquid level. What devices are generally installed for this purpose even when a tank liquid-level indicating system is provided?
(A) Sounding tubes
(B) Overflow tubes
(C) Vent tubes
(D) Stripping pipes
39.39. The increase of compression ratio of a gas turbine with Brayton cycle will increase the __________ .
(A) fuel consumption
(B) isentropic efficiency
(C) cut-off ratio
(D) thermal efficiency
40.40. For a diesel engine an initial downward stroke of the piston draws in the air to charge the cylinder, which is followed by the compression stroke, with the fuel being injected as top dead center is approached, then a downward power stroke, and an upward exhaust stroke. Which type of engine is called for this operation?
(A) Two-stroke engine
(B) Four-stroke engine
(C) Supercharging engine
(D) Ideal cycle engine