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1、49期轮机英语1. In order to concrol thermal stresses ,some types of modern engines use pistons with _D_A heavy wall and intensive cooling B heavy wall and no cooling Cthin wall and no cooling D thin wall and intensive cooling 2. The average pressure exerted on a piston during each power stroke is termed -
2、B-A indicated B ean effective pressure C exhaust back pessure Dcompression pressure 3. The ignition quality of a diesel fuel is indicated by the_A_A cetane number B volatility point C viscosity index Doctane number 4. A piston in a four stroke cycle disesel engine makes four stroke during each _B_A
3、crankshaft revolution B mechanical cycle of operation 5._A_ 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. The pressure switch 6.Constant cooling the various components o
4、f diesel engine has a number of functions except for _D_. A. good lubrication B. low thermal stress C. good mechanical properties D. acid corrosion 7.A device which functions to bring a diesel engine to a full stop to protect it from damage is known as a/an _B_. A. torque limiter B. over-speed trip
5、C. over-speed governor D. load limit governor 8.Engine speeds at which resonance can occur are termed _D_. A. maximum speeds B. full speeds C. sea speeds D. critical speeds 9.Prolonged operation of a diesel engine with a closed cooling water system at lower than normal designed operating temperature
6、s can _D_. A. increase power output B. decrease lube oil viscosity C. eliminate fuel knock D. cause sulfuric acid formation 10 In a diesel engine lube oil system ,which of the following parts should be lubricated first ?B-A camshaft bearings B Main bearings C Piston crowns D Cylinder walls11 A large
7、 ,low speed ,main propulsion diesel engine uses sea water to directly cool the _C_A cylinder heads B exhaust valves C scavenging air D injectors 12 In a rubocharger ,inlet air velocity is increased in the _D_A inlet nozzle ring B stationary diffuser passages C compressor outlet volute D rotating imp
8、eller vanes 13 Each cylinder has one starting valve which is usually opened by air pressure and closed by _C_A nuts and bolts B new joints C spring force D sealing rings 14 In a simple mechanical governor ,the _B_A centrifugal force rotates the ball-head B Flyweight centrifugal force is balanced by
9、spring force C flyweight centrifugal force is balanced by hydraulic pressure Dspeeder spring alone actuates the fuel control rod 15 A pyrometer is an instrument commomly used to measure _C_A cylinder pressure B flame intensity C exhaust gas temperature D crankshaft axial aliganment 16 After starting
10、 a disesel engine ,which of listed opetating conditions should be checked first?B-Aair box pressure B lube oil pressure C Exhaust temperatures D raw watert perssure 17 A high temperature alarm or _C_which will melt is used to guard against the explosion of compressor air pipelines A a flame trap B a
11、 relief valve C a fusible plug D a bursting cap 18 What preventative maintenace should be done frequently to diesel engine starting air receivers?A-A drain the accumulated moisture B.Test the relief valves.C.Watch the temperature to prevent fluctuations in pressure.D.Clean the interior to remove oil
12、 and foreign matter.19 In reducing engine speed to an efficient propeller speed by the use of reduction gears ,_C_Aspeed 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
13、Which of the following statements concerning fire-tube boilers is correct ?-A-A Combustion gases flow through the tubes B Flames impinge on the tubesC Combustion occurs in the tubesD Water flows through the tubes21 The exhaust boilers are used to recover some of _C_carried in the exhaust gas from th
14、e main engine A water B oil C heat D steam22 The water level in a steaming auxiliary boiler will always _D_A rise when the steam pressure is in creased B remain constant as long as the feed pump operates C fall when the steam pressure is decreased D vary as the steam demand changes 23 when lighting off an auxiliary boiler ,which of the problems listed could cause the burners to sputter ?D-A cold fuel oil B low fuel oil pressure C low atomizing steam pressure D Water in the fuel oil 24 If the feed pump for an auxiliaty boier fails to deliver the feed water to the boiler ,the cause ma
