第46期轮机英语试题

第46期轮机英语试题

一单项选择题

D1. In order to concrol thermal stresses ,some types of modern engines use pistons with __

A heavy wall and intensive cooling

B heavy wall and no cooling

Cthin wall and no cooling D thin wall and intensive cooling

B2. The average pressure exerted on a piston during each power stroke is termed

A indicated

B ean effective pressure

C exhaust back pessure

D compression pressure A3. The ignition quality of a diesel fuel is indicated by the___

A cetane number

B volatility point

C viscosity index Doctane number

B4. A piston in a four stroke cycle disesel engine makes four stroke during each __

A crankshaft revolution

B mechanical cycle of operation

C period of two cobustion cycles

D cycle of two events

C5. Crankshafts of medium speed engines are _____from a single piece of steel

A unusually solid welded

B never be solid forged

C almost invariably

D almost invariably be welded

B6 .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

D7 .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

B8 .Compared to four stroke cycle engines ,two ~stroke /cye 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

A9. _____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 metet DThe pressure switch

B10. 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 C11 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

D12. In a rubocharger ,inlet air velocity is increased in the __________

A inlet nozzle ring

B stationary diffuser passages

C compressor outlet volute

D rotating impeller vanes

C13 .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

B14. In a simple mechanical governor ,the _________

A centrifugal force rotates the ball-head