轮机英语大证考试真题46期

第46期轮机英语试题

一、单项选择题

1. In order to control thermal stresses ,some type of modern engines use piston with______.

A. heavy wall and intensive cooling

B. heavy wall and no cooling

C. thin wall and no cooling

D. thin wall and intensive cooling

2. The average pressure exerted on a piston during each power stroke is termed______.

A. indicated horsepower

B. mean effective pressure

C. exhaust back pressure

D. compression pressure

3. The ignition quality of a diesel fuel is indicated by the ______.

A. cetane number

B. volatility point

C. viscosity index

D. octane number

4. A piston in a four-stroke/cycle diesel engine makes four strokes during each ______.

A. crankshaft revolution

B. mechanical cycle of operation

C. period of two combustion cycles

D. cycle of two events

5. Crankshafts of medium speed engines are ______ from a single piece of steel.

A. unusually solid welded

B. never be solid forged

C. almost invariably solid forged

D. almost invariably be welded

6. The starting air entering the cylinder begins when the piston______.

A. has nearly come to the TDC

B. has just past the TDC

C. has nearly come to the BDC

D. has just past the BDC

7. A main bearing consists of two shells which are secured by means of studs and ______.

A. tie rods

B. through bolts

C. lead wires

D. bearing caps

8. Compared to four-stroke/cycle engines, two-stroke/cycle diesel engines have the disadvantage of ______.

A. less even torque

B. higher cylinder head temperatures

C. fewer power strokes per revolution

D. greater weight/size requirements

9.______ controls the fuel oil temperature in order to provide oil at the correct viscosity for combustion.

A. The viscosity regulator

B. The temperature controller

C. The flow meter

D. greater weight/size requirements

10. In a diesel engine lube oil system, which of the following parts should be lubricated first?

A. Camshaft bearings

B. Main bearings

C. Piston crowns

D. Cylinder walls

11. A large, low-speed, main propulsion diesel engine uses sea water to directly cool the ______.

A. cylinder heads

B. exhaust valves

C. scavenging air

D. injectors

12. In a turbocharger, inlet air velocity is increased in the ______.

A. inlet nozzle ring

B. stationary diffuser passages

C. compressor outlet volute

D. rotating impeller vanes

13. Each cylinder has one starting valve which is usually opened by air pressure and closed by______.

A. nuts and bolts

B. new joints

C. spring force

D. sealing rings

14. In a simple mechanical governor, the ______.

A. centrifugal force rotates the ball-head