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单选题
If the flame from combustion in the cylinder of a four-stroke engine past the piston into the space below, the accumulation of flammable mixture would be ignited, thus resulting in （）.
A
the crankcase explosion
B
lifting of the cylinder safety valve
C
a scavenge fire
D
opening of the manhole
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更多 “单选题If the flame from combustion in the cylinder of a four-stroke engine past the piston into the space below, the accumulation of flammable mixture would be ignited, thus resulting in （）.A the crankcase explosionB lifting of the cylinder safety valveC a scavenge fireD opening of the manhole” 相关考题
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Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?A.Control the amount of lube oil burned in the combustion chamberB.Transmit heat from the piston to the cylinder linerC.Prevent damage to ring groove inserts by acting as a heat damD.Dissipate combustion chamber gas pressure by channeling it through the ring gap
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Diesel engine blow-by is the leakage of combustion gases past the( ).A.oil rings onlyB.compression and scraper ringsC.cylinder liner sealingD.cylinder liner ring grooves
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第一组： The Wartsila 50DF operates on the lean-bum principle: the mixture of air and gas in the cylinder has more air than is needed for complete combustion. Lean combustion reduces peak temperatures and therefore NOx emissions. Efficiency is increased and higher output is reached while avoiding knocking. Combustion of the lean air-fuel mixture is initiated by injecting a small amount of LFO (pilot fuel) into the cylinder. The pilot fuel is ignited in a conventional diesel process, providing a high-energy ignition source for the main engine. To obtain the best efficiency and lowest emissions, every cylinder is individually controlled to ensure operation at the correct air-fuel ratio and with the correct amount and timing of pilot fuel rejection. Wartsila has developed a special electronic control system to cope with the demanding task of controlling the combustion in each cylinder, and to ensure optimal performance in terms of efficiency and emissions under all conditions by keeping each cylinder within the operating window. Stable and well-controlled combustion also contributes to less mechanical and thermal load on the engine components. Current stringent emission regulations demand the reduction of NOx emissions. In an internal combustion engine this means controlling peak temperature and residence time, which are the main parameters governing NOx formations. In the Wartsila 50DF engine, the air-fuel ratio is very high (typically 2.2). Since the same specific heat quantity released by combustion is used to heat up a larger mass of air, the maximum temperature and consequently NOx formation are lower. The mixture is uniform. throughout the cylinder since the fuel and air are premixed before introduction into the cylinders, which helps to avoid local NOx formation points within the cylinder. Benefiting from this unique feature, NOx emissions from the Wartsila 50DF are extremely and comply with the most stringent existing legislation.What is the combustion feature of the Wartsila 50DF?A.Lean air in the cylinderB.Excessive fuel in the cylinderC.Excessive air in the cylinderD.Spark ignition
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For the Wartsila 50DF, the complete combustion compared with the lean-combustion can decrease the following results ____ .①Exhaust temperatures ②NOx emissions ③Propeller efficiency ④Output ⑤Cylinder knocking ⑥Fuel supplyA.①②B.③⑥C.④D.④⑤
考题
If the flame from combustion in the cylinder of a four-stroke engine past the piston into the space below, the accumulation of flammable mixture would be ignited, thus resulting in _____.A.the crankcase explosionB.lifting of the cylinder safety valveC.a scavenge fireD.opening of the manhole
考题
How does combustion air enter the cylinder of a two-cycle diesel engine ? Through _______．A.Cylinder head valvesB.PortsC.Turbo chargersD.Bleeder valves
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Flame screens are used to ______.A.contain flammable fumesB.protect firefightiers from flamesC.prevent flames from entering tanksD.keep flame and sparks from getting out of an engine’s exhaust system
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单选题The primary purpose of oil control rings on a diesel piston is to（）A
provide a reservoir for cylinder lubricationB
pump oil into the combustion space for cylinder coolingC
prevent excessive lubricating oil consumptionD
allow hydraulic oil film formation on the cylinder
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单选题To function properly, oil control rings used on a diesel engine piston must distribute sufficient oil to all parts of the cylinder wall and must also（）.A
prevent any lubricant from reachingB
prevent excessive lubrication from reaching the combustion spaceC
Provide metal-to-metal contact to seal the cylinder against blow-byD
assure a positive means of scraping carbon accumulation from the cylinder
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单选题Proper combustion in a boiler would be indicated by （）.A
yellowish flameB
golden yellow flameC
white flameD
brilliant white flame
考题
单选题White smoke exhausting from a diesel engine can be caused by a （）A
high combustion temperatureB
high compression pressureC
cracked cylinder linerD
fuel with a high vanadium content
考题
单选题The diameter of a piston is usually less at the crown than at the skirt, in order to （）.A
facilitate the installation of piston ringsB
allow for the expansion of the piston during operationC
prevent crankcase vapors from entering the combustion chamberD
reduce wearing of the upper cylinder liner
考题
单选题Which of the following statements represents the function of the compression rings installed at the top of a diesel Engine piston?（）A
Control the amount of lube oil burned in the combustion chamberB
Transmit heat from the piston to the cylinder linerC
Prevent damage to ring groove inserts by acting as a heat damD
Dissipate combustion chamber gas pressure by channeling it through the ring gap
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单选题The most practical way of detecting an overload in one cylinder of an operating large, low-speed ,main propulsion diesel engine is to （）A
check the cylinder exhausts for black smokeB
listen for combustion knock in that cylinderC
isolate each cylinder and inspect the injectorD
check the cylinder exhaust temperature frequently
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单选题The cylinder head, cylinder liner and （） form the combustion chamber.A
frameB
pistonC
crankcaseD
explosion plate
考题
单选题Internal combustion engine crankcase vent outlets must be equipped with （）A
hinged rain guardsB
corrosion resistant flame screensC
dipsticks for measuring oil levelsD
crankcase ventilation fans
考题
单选题The main purpose of the piston oil scraper rings is to （）.A
seal the space between the piston and the linerB
reduce the amount of lube oil burned in the combustion chamberC
transmit heat from the piston to the cylinder linerD
damp out fluctuations of the piston side thrust
考题
单选题Persistent knocking of one cylinder of a diesel engine ceases when the fuel supply to that cylinder is securedThis problem may be a result of （）A
low loading of that cylinderB
faulty combustion in that cylinderC
sluggish piston ring actionD
excessive piston cooling
考题
单选题Because of the resulting higher pressures in the cylinder from the combustion of this greater mass of fuel, and the larger diameters, the liner must be made （） at the top to accommodate the higher stresses, and prevent cracking of the material.A
thinnerB
thickerC
smootherD
rougher
考题
单选题How does combustion air enter the cylinder of a two-cycle diesel engine?（）A
Cylinder head valvesB
PortsC
Turbo chargersD
Bleeder valves
考题
单选题Combustion gases formed in the cylinder of a diesel engine are prevented from blowing past the piston by （）A
cylinder valvesB
compression ringsC
piston skirtsD
oil rings
考题
单选题The longer the ignition delay period resulting from improper use of low cetane fuel, the （）A
less fuel will enter the cylinderB
higher the cylinder combustion temperatureC
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more rapid the rise in combustion pressure
考题
单选题Which statement about diesel engine combustion is true?（）A
Combustion does not begin until the piston starts down on the power strokeB
Maximum combustion pressure is reached before TDCC
Turbulence in the cylinder causes a delay in ignitionD
Maximum cylinder firing pressure is not developed until the piston passes TDC
考题
单选题In the cylinder of a diesel engine fuel is ignited by the（）A
spark from a plug in the pre-combustion chamberB
electrical discharge from the distributorC
heat of compression within the cylinderD
heat from the fuel injection nozzle
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单选题The function of diesel engine piston compression rings is to （）.A
prevent piston side thrustB
prevent engine friction lossesC
transmit heat from the piston to the cylinder linerD
remove oil from the cylinder combustion space
考题
单选题Piston compression rings used in a diesel engine function to （）A
transfer heat from the cylinder to the pistonB
scrape oil from the sides of the pistonC
seal the combustion space from the crankcasesD
prevent any piston contact with the cylinder liner
考题
单选题Proper dispersion of fuel in a diesel engine cylinder is dependent upon the （）A
injection pressureB
shape of combustion spaceC
turbulence in combustion spaceD
all of the above
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