轮机英语真题46期,甲类三管轮

轮机英语全国统考试题(总第46期)

一、单项选择题

1. In order to control thermal stresses,some types of modern engines use pistons 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 eff ective pressure

C.exhaust back pressure

pression pressure.

3.The ignition quality of a diesel f uel is indicated by the

A.cetane number

B.volatility point

C.viscosity index

D.octane number

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

A.crankshaf t revolution

B.mechanical cycle of operation

C.period of two combustion cycles

D.cycle of two events

5.Crankshaf ts of medium speed engines are f rom a single piece of steel.

A.unusually solid welded

B.never be solid f orged

C.almost invariably solid f orged

D.almost invariably be welded

6.The start ing 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

pared to f our-stroke/cycle engines,two-stroke/cycle diesel engines have the disadvantage of.

A.less even torque

B.higher cylinder head temperatures

C.f ewer power strokes per revolution

D.greater weight/size requirements

9. controls the f uel oil temperature in order to provide oil at the correct viscosity f or combustion.

A.The viscosity regulator

B.The temperature controller

C.The f low meter

D.The pressure switch

10.In a diesel engine lube oil system,which of the f ollowing parts should be lubricated f irst?

A.Camshaf t 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 dif f user passages

pressor 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 nad bolts

B.new joints

C.spring f orce

D.sealing rings

14.In a simple mechanical governor, the

A.centri f ugal f orce rotates the ball-head

B.f lyweight centri f ugal f orce is balanced by spring f oce

C. f lyweight centri f ugal f orce is balanced by hydraulic pressure

D.speeder spring alone actuat es the f uel control rod

15. A pyrometer is an instrument commonly used to measure

A.cylinder pressure

B.f lame intensity

C.exhaust gas temperature

D.crankshaf t axial alignment

16.Af ter starting a diesel engine,which of the listed operating conditions should be checked f i rst?

A.Air box pressure

B.Lube oil pressure

C.Exhaust temperatures

D.Raw water pressure

17.A high temperature alarm or which will melt is used to guard against the explosion of compressor air pipelines. A.a f lame trap B. a relief valve

C.a f usible plug

D.a bursting cap

18. What preventative maintenance should be done frequently to diesel engine starting air receivers?

A.Drain the accumulated moisture.

B.Test the relief valves.

C.Watch the temperature to prevent f luctuations in pressure.

D.Clean the interior to remove oil and f oreign matter.

19.In reducing engine speed to and eff i cient propeller speed by the use of reduction gears,

A.speed and torque are both reduced

B.speed is reduced and torque remains unchanged

C.speed is reduced and torque is increased

D.speed is sometimes unchanged while torque is increased

20.Which of the f ollowing statements concerning f ire-bube boilers is correct?

bustion gases f low through the tubes.

B.Flames impinge on the tubes.

bustion occurs in the tubes.

D.Water f lows through the tubes.

21.The exhaust boilers are used to recover some of carried in the exhaust gas f rom the main engine .

A .water B.oil C.heat D.steam

22.The water level in a steaming auxiliary boiler will always .

A.rise when the steam pressure is increased

B.remain constant as long as the f eed pump operates

C.f all when the steam pressure is decreased

D.vary as the steam demand changes

23.When lighting of f an auxiliary boiler,which of the problems listed could cause the burners to sputter?

A.Cold f uel oil

B.Low f uel oil pressure

C.Low atomizing steam pressure

D.Water in the f uel oil

24.If the f eed pump f or and auxiliary boiler f ails to deliver the f eed water to the boiler,the cause may be

A.high steam pressure in the boiler

B.abnormally high f eed-water temperature

C.abnormally high boiler water temperature

D.steam demand exceeding feed pump capacity

25.Through a pump,the liquid is transferred from the suction to the discharge by the mechanical variation of the volume of a chamber or chambers.

A.positive displacement

B.ejector

C.centrif ugal

D.air compressor

26.Sealing lines provide sealing liquid f low to the stuf f ing box of a centri f ugal pump

A.to prevent seawater from passing out the stuff ing box when a high suction head is present

B.to cool the shaf t

C.in place of mechanical seals

D.in place of lantern rings

27.Which of the valves listed will be cycled from f ully open to f ully close when the handle is turned 90 degree?

A. A rising stem gate valve

B.A globe stop valve

C.A check valve

D. A butterf ly valve

28.Centrif ugal pumps,used to handle hot liquids, must have a minimum f low through them under all operating conditions.This f low serves to

A.prevent overheating and damage to pump rotating parts due to rubbing

B.maintain the net positive suction head of the pump

C.maintain hydraulic dif ferential in the pump impeller passages

D.purge the pump of non-condensable vapors and gases

29.If you heard a …crackling‟noise in a centrif u gal pump, the most probable cause of the problem would be

A.insuff icient speed

B.cavitation

C.excess discharge pressure

D.excessive net positive suction head

30.In the process of,liquid changes into gas.

A.evaporation Bf rosting

C.condensing

pressing