單項(xiàng)選擇題Generating tubes in waste heat boilers are finned to （）.

A.reduce gas flow turbulence
B.prevent exhaust gas corrosion
C.increase the rate of combustion
D.increase the rate of heat transfer


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1.單項(xiàng)選擇題Directional intake ports in diesel engines are used to （）.

A.reduce air charge turbulence
B.induce air swirl
C.deflect hot combustion gas away from the valves
D.oppose the effects of piston induced squish

2.單項(xiàng)選擇題Mist detectors used on large low-speed main propulsion diesel engines monitor and check for the presence of （）.

A.fuel oil vapor at the sludge tank vent
B.unburned fuel vapors in the scavenge air receiver
C.lube oil vapors in the crank case
D.lube oil vapors in the engine room

3.單項(xiàng)選擇題Clearance volume scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished （）.

A.during the valve overlap period
B.with only the exhaust valve open
C.at a pressure below atmospheric
D.without cooling the cylinders or pistons

4.單項(xiàng)選擇題To prevent vibration damage to the fuel supply line of a diesel engine, you may use （）.

A.a short length of heavy duty clear plastic tubing
B.a length of approved flexible nonmetallic hose
C.welded flange connections for all joints
D.aluminum piping with expansion loops

5.單項(xiàng)選擇題When the prime movers of two paralleled generators are equipped with mechanical- hydraulic governors, and are operating within their designed range, the unit with the least amount of speed droop will （）.

A.pick up more of any increase in load
B.pick up less of any increase in load
C.share an equal amount of any increase in load
D.drop an equal amount of any decrease in load