大管轮英语补充题.doc

The distance between the bottom of the hull and the waterline is called _. A. tonnage B.reserve buoyancy C. draft D.freeboard For an upright vessel, draft is the vertical distance between the keel and the _. A. waterline B.freeboard deck C. Plimsoll mark D.amidships section he trim of a vessel is the _. A. value of the mean draft B. degree of list C. amount of roll D. difference in fore and aft drafts The difference between the starboard and port drafts caused by a transverse shift in weight is _. A. list B. heel C. trim首尾吃水差 D. flotation When a ship in loaded condition floats at arbitrary water line, its displacement is to the relevant mass of water displace A. equal B. larger C. smaller D. equivalent The displacement of a ship is to the total weight, all told, of the relevant loaded ship. A. larger B. equal C. smaller D. equivalent If the buoyant force on a ships hull is equal to or greater than the displacement tonnage, the ship will _. A. require ballast added to only the port side tanks B. be down by the head C. sink D. float You may improve a vessels stability by _. A. keeping the fuel tanks topped off B. increasing the free surface effect C. keeping the fuel tanks at least haft full D. keeping at least one fuel tank empty for slops The stability of a vessel is normally the greatest when all fuel and water tanks are full because the _. A. center of gravity is lowered B. center of buoyancy is lowered C. reserve buoyancy is unchanged D. hull freeboard is increased The depth of the ship below waterline measured vertically to the lowest part of the hull is called . A. trim B. lean C. draft D. tonnage Some medium and high speed diesel engines require reduction gear units to provide a useful propeller speed. In most reduction gears, the bull gear . A. must churn the oil in the sump B. is connected to the propeller shaft C. is driven at the highest rpm D. compensates for alignment variations between the engine and pinion gear When used with reversing reduction gears, medium-speed diesel engines should be bolted to their foundations with fitted bolts at the drive end and clearance bolts in other locations. This is done to . A. maintain alignment when the ships hull is working in heavy seas B. ensure engine vibrations correspond to the natural frequency of the hull C. permit the engine to expand away from the driven equipment as the engine heats up and expands D. maintain engine thrust bearing clearances What determines the number of events occurring in a cycle of operation in an internal combustion engine? A. Crankshaft revolution. B. Type of engine . C. Distance a piston travels during a stroke. D. Number of pistons. Gas turbines differ from steam engines in that _. A. steam rather than gas is used to turn a shaft B. vapor rather than gas is used to turn a shaft C. the former uses gas to turn a shaft D. the latter uses gas to turn a shaft The main operating characteristic of diesel engines which distinguishes them from other internal combustion engines is the . A. method of supplying air B. cooling system C. method of igniting fuel D. valve operating mechanism Which of the following reasons represents why the designed compression ratio of a gasoline engine is lower than that of a diesel engine? A. Compression must be low for effective spark ignition B. Compression must be low for required horsepower and torque generation C. Compression must be low to prevent pre-ignition D. Compression must be low to have effective pre-ignition Large, slow speed, two-stroke marine diesel engines offer the advantages of the following except _. A. burning poorer quality, cheaper fuel B. providing large power C. being reversible D. using less oil than medium speed engines Why are slow speed diesel engines especially tall? A. Because in this way the piston can be withdrawn downwards. B. The engine can occupy larger space. C. The engine may have long strokes which improve engine efficiency. D. More maintenance is provided. Large, slow speed, two-stroke marine diesel engines are directly coupled to the propeller and do not require a _. A. piston B. gearboxes C. crankshaft D. thrust block Since most medium-speed diesel engines are non-reversible, what is usually used to cater for astern thrust? A. a reversing gear B. a controllable pitch propeller C. a fixed pitch propeller D. a clutch Medium speed engines have the following advantages except_. A. Medium speed engines use less oil than slow speed engines B. Medium speed engines of later type are capable of burning low quality heavy fuel oil. C. The engines have long strokes which improve engine efficiency D. The engines are compact, thus providing more spaces for cargoes and passengers. Power is defined as the _. A. rate of doing work B. amount of force needed to overcome friction C. amount of work accomplished D. distance through which an object is moved Mechanical energy in transition is referred to as _. A. horsepower B. work C. heat D. velocity Which of the following terms could be applied to the simple definition “the energy of motion”? . A. Electrical energy B. Thermal energy. C. Potential energy. D. Kinetic energy. The most important factor in engine performance is the actual power output at the end of the crankshaft available for doing work. This is known as _. A. indicated horsepower B. brake horsepower C. net horsepower D. friction horsepower The is the power available at the output shaft of the engine and can be measured using a torsionmeter or with a brake. A. electric power B. shaft power C. indicated power D. mechanical power Maximum horsepower of a diesel engine is attained . A. when the engine rpm is pulled down by overload B. at rated engine rpm C. at 95 % of rated engine rpm D. at 95 % of a properly adjusted governor rpm with the engine under full load A four cylinder, four-stroke/cycle, single acting diesel engine has a 740mm bore and a 1500mm stroke. What indicated power will be developed if the average mean effective pressure is 18kg/ cm2 at a speed of 90 RPM? A. 3416kW B. 4644kW C. 7296kW D. 9290kW A seven cylinder, two-stroke/cycle, single acting diesel engine with a cylinder indicated horsepower calculated as 1350 kW and brake horsepower measured at 7466kW has a mechanical efficiency of _. A. 18% B. 55% C. 79% D.83% An eight cylinder, four-stroke/cycle, single acting diesel engine has a 650 mm bore and a 1400 mm stroke, effective pressure is 30kg/ cm2 at a speed of 100 rpm, its capacity should be .? A.1689km B.9111kw C.12388kw D.24776kw Suppose the rated capacity of the main engine of a ship is 10,000 KW at 100 rated rpm, then when at 80 rpm its capacity should be . A. 800 KW B. 5120 KW C. 6400 KW D. 4180 KW If your vessel burns 8 tons of fuel per hour at 15 knots，how many tons per hour will it burn at 18 knots? A. 13.82 tons. B. 15.61 tons. C. 16.00 tons. D. 16.37 tons. The cubic inch displacement of a cylinder is determined by the diameter of the piston and the . A. length of the crankshaft B. volume of the clearance space C. weight of piston D. length of the stroke The bore of a diesel engine cylinder describes the _. A. swept volume of the cylinder B. inside diameter of the cylinder C. piston displacement in the cylinder D. length of the piston stroke According to the principle of four-stroke diesel engine, what is the number of its efficient work stroke per revolution? A. 1/2 B. 1 C. 2 D. 3 According to the principle of two-stroke diesel engine, what is the number of its efficient work stroke per revolution? A. 1/2 B. 1 C. 2 D. 3 The ratio of the brake horsepower to the indicated horsepower of a diesel engine is its _. A. thermal efficiency B. mechanical efficiency C. brake thermal efficiency D. volumetric efficiency “AMIDSHIPS” refers to _. A. back of the vessel B. the middle portion of a ship C. a backward movement of a vessel D. across the ship, at right angles to the fore-and-aft centerline _ power is the power developed within the cylinder and can be measured by an engine indicator. A. The shaft B. The mechanical C. The electric D. The indicated Use the following equation to calculate the cylinder oil feed rate at specified MCR: Q = BSPe2410-3 , Q = Feed rate at specified MCR BS = Basic Setting, see Item 4.3 Pe = Effective engine power at specified MCR Engine Type Pe at Specified MCR Basic Setting at Specified MCR 6L60MC 15600 1.0 6S80MC 29700 1.2 The cylinder oil feed rate at specified MCR of 6L60MC is _. A. 855.4 B. 374.4 C. 449.3 D. 712.8 In crosshead engines in good condition the cylinder oil consumption may usually be . A. below 0.l g/hp.hr. B. above 10 g/hp.hr. C. below l.0 g/hp.hr. D. zero In a diesel engine, the time taken to heat the fuel particles, turn them into vapor, and bring about combustion is called _ A. injection lag B. ignition delay C. compression ignition D. turbulence lag For a particular engine power the two-stroke engine will be considerably lighter. _ the complicated valve operatin A. Nor the two-stroke engine requires B. Nor does the two-stroke engine require C. Nor the two-stroke engine require D. Nor do the two-stroke engine require Modern marine diesel engines using mechanical fuel injection, operate on a combustion cycle which is _. A. a combination of constant volume and constant pressure B. a combination of constant temperature and constant pressure C. entirely constant pressure D. entirely constant volume Most practical diesel engines today operate on cycle which is a combination of the Diesel and Otto cycles. In this process, compression ignition _ A. begins on a constant volume basis B. begins on a constant pressure basis C. ends on a constant volume basis D. begins and ends on a constant volume basis An indicator card or pressure-volume diagram, shows graphically the_. A. compression ratio of the engine B. volume of the engine C. relationships between pressure and volume during one stroke of the engine D. relationships between pressure and volume during one cycle of the engine Turbulence is created in the cylinders of a diesel engine to . A. obtain injection lag B. help mix fuel and air C. increase combustion pressure D. utilize higher injection pressures Turbulence of the compressed air charge in a diesel engine cylinder increases _. A. ignition lag B. piston side thrust C. the efficiency of the engine D. compression pressure Which of the following relationships should occur between the temperature developed in a combustion space, and the compression ratio of the engine? A. Higher compression ratios create higher temperature. B. Higher temperatures create higher compression ratios. C. Lower temperatures create higher compression ratios. D. Higher compression ratios create lower temperatures. Because the top of the connecting rod swings about the pin and changes direction each time the piston reaches mid stroke, the relative speed between the bearing and pin at mid stroke is zero, _to a maximum as the piston approaches top or bottom dead center and then _back to zero again as the piston approaches mid stroke and the connecting rod changes direction. A. accelerates/decelerates B accelerates/ accelerates C. decelerates/decelerates D decelerates/ accelerates Which of the factors listed has the greatest effect on the mechanical efficiency of a diesel engine? A. Temperature of the intake air. B. Friction within the engine. C. Mechanical condition of the supercharger. D. Mechanical condition of the turbocharger. The purpose of an interference angle in a diesel engine exhaust valve is to _. I. Break up seat deposits II. Work in conjunction with valve rotators to rotate the valve A. I only B. II only C. Both I and II D. Neither I nor II Exhaust valve openings in a diesel engine cylinder head are made as large as practical to . A. increase back pressure during the exhaust process B. facilitate periodic replacement of the valves C. reduce the pumping loss associated with scavenging D. reduce tension on valve springs Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to . A. provide added wear protection against todays corrosive quality of fuel B. increase overall valve strength due to the high gas pressures C. assist in dissipating heat due to the extreme operating temperatures D. reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering The size of the exhaust valve opening is . A. most critical in a four-stroke cycle diesel engine B. most critical in a two-stroke/cycle diesel engine C. most critical in a four-stroke/cycle diesel engine if it is turbocharged D. of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine Diesel engine mufflers reduce noise by _. A. packing muffler chambers B. the use of long head pipes C. the use of zinc electrodes D. changing exhaust gas direction Diesel engine mufflers or silencers reduce the engine exhaust noise by . A. passing the exhaust through long head pipes B. diffusing exhaust vibrations through activated carbon baffles C. increasing the exhaust gas velocity D. reducing the exhaust gas velocity What is the meaning of the term valve clearance? A. The clearance between the rocker arm and valve pushrod. B. The clearance between valve spindle disc and seat. C. The clearance between the rocker arm and camshaft pushrod. D. The clearance between the rocker arm and valve pushrod in either warm or cold state A turbocharged diesel engine will have an intake manifold pressure . A. constantly decreasing as engine load increase B. constantly increasing as the amount of supercharging increases C. approximately equal to exhaust manifold pressure at all times D. approximately equal to atmospheric pressure at all times Why is the ring belt narrower in diameter than the skirt of a piston designed for a diesel engine? A. To allow for greater expansion due to higher operating temperature B. To seal the cylinder against leakage of combustion gases. C. To provide an additional surface for oil cooling. D. To provide an additional strength for the crown and lower structure. Many cast iron pistons are designed with heat dams, which serve to . A. keep piston crown temperatures elevated for smoother combustion B. reduce the possibility of overheating the top compression ring C. help retain the heat of compression to prevent ignition delay D. help retain the heat of compression to prevent combustion knock To facilitate early ring seating of newly installed piston rings, while still providing extended ring wear, _. A. a taper faced ring can be used B. the cylinder surface is honed to the smoothest surface attainable C. inlaid rings can be utilized in which the chrome center of the ring face slightly protrudes beyond the cast iron edges D. rings with increased back clearance are provided The main reason for using bimetallic piston rings is to _. A. increase engine thermal efficiency B. reduce specific fuel consumption C. reduce the probability of ring fracture D. allow for ring expansion Ring groove inserts are occasionally used on aluminum alloy piston to _. A. reduce the ring groove wear rate B. seal against crankcase vapors C. lessen the wear on aluminum part of the cylinder D. allow for the greater expansion rate of aluminum Oil control rings used in two-stroke/cycle diesel engines are located near the bottom of the piston skirt in order to . A. increase the liner area covered by the oil film B. maintain an oil film on the lower liner where scuffing is prevalent C. keep excess oil away from intake and exhaust ports D. help cushion piston skirt side thrust by providing a hydrodynamic oil wedge Insufficient end clearance on newly fitted piston rings in a diesel engine will cause the rings to _. A. jam in the least worn part of the cylinder when the rings expand B. break in the most worn part of the cylinder when the rings expand C. wear eccentrically on the side opposite the end gap D. overheat and jam at the top center on the combustion stroke If the piston ring gap remains insufficient when installing new rings, you should _. A. install oversized rings B. hone the cylinder liner to allow ring installation C. compress the rings tighter with a compressing tool D. file the ends of the rings The purpose of piston ring end clearance is to _. A. allow the combustion gases to press the ring down on the land B. allow the combustion gases to get behind the ring and press it against the cylinder liner C. prevent buckling and breaking of the ring D. aid in protecting the oil film A properly honed diesel engine cylinder liner will _. A. prevent piston ring wear B. shorten the ring break-in period C. prevent cylinder liner gazing D. appear slick and glazed Which of the listed cylinder liner surface conditions indicates proper lubrication? A. Dull black appearance. B. Bright appearance. C. Thin layer of lacquer D. Thick oily film. One of the advantages in the use of a dry liner over a wet liner is _. A. it is fitted with neoprene O-ring seals B. the honing process makes it easier to maintain the desired oil film C. there is less likelihood of