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How does combustion air enter the cylinder of a two-cycle diesel engine ? Through _______．
A.Cylinder head valves
B.Ports
C.Turbo chargers
D.Bleeder valves
参考答案
更多 “ How does combustion air enter the cylinder of a two-cycle diesel engine ? Through _______．A.Cylinder head valvesB.PortsC.Turbo chargersD.Bleeder valves ” 相关考题
考题
Fuel droplets injected into a diesel engine cylinder must have adequate penetration to ____.A.prolong the ignition delay periodB.ensure the beginning of fuel injectionC.thoroughly utilize the air chargeD.allow controlled fuel combustion
考题
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
考题
If the diesel engine fuel injection timing is changed to delay the start of injection until the pistons are at top dead center, the engine will_________.A.backfire through the air intakesB.develop less power under loadC.have high firing pressuresD.lift its cylinder relief valves
考题
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
考题
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
考题
Diesel engines obtain combustion air through turbo chargers，blowers，or ______．A.Air startersB.CarburetorsC.Natural aspirationD.Air receivers
考题
单选题Air scavenging of a diesel engine cylinder（）A
blows out the exhaust gasesB
supplies oxygen for combustionC
cools the valves and cylinder wallsD
all of the above
考题
单选题Poor combustion in a diesel engine can be caused by （）.A
high compression pressureB
low intake air temperatureC
low exhaust pressureD
high scavenge air temperature
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
考题
单选题The most serious effect of air trapped in a diesel engine jacket water cooling system is that it（）.A
causes colloid suspension in the cooling waterB
reduces the capability of the lubrication systemC
can form pockets which block the flow of coolant through the systemD
leads to the scuffing of cylinder walls
考题
单选题The term diesel engine scavenging means（）A
delivering more air into the cylinder than it would normally receive during an ordinary charging processB
forcing the products of combustion out of the cylinder with the fresh air chargeC
collecting the air charge at the cleanerD
combustion and expansion of hot gas
考题
单选题The diesel engine is a type of internal combustion engine which ignites the fuel by injecting it into hot, high pressure air in a （）.A
air bottleB
air compressorC
crank caseD
combustion chamber
考题
单选题If the diesel engine fuel injection timing is changed to delay the start of injection until the pistons are at top dead center, the engine will（）A
backfire through the air intakesB
develop less power under loadC
have high firing pressuresD
lift its cylinder relief valves
考题
单选题As for a diesel engine, lack of combustion air may be due to （）.A
fouling turbineB
fuel pump faultsC
lubrication failureD
excessive cooling
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 occurs in a diesel engine, the （）.A
less fuel will enter the cylinderB
lower will be cylinder compression temperaturesC
more complete will be fuel combustionD
more rapid will be the rise in combustion pressure
考题
单选题If the engine does start on air, but combustion does not immediately begin, the cause may be （）.A
failure of the fuel pumpsB
starting air pressure too lowC
stop valve in air line closedD
the turning gear still engaged
考题
单选题Fuel is admitted to a diesel engine cylinder through the （）.A
intake valvesB
carburetorC
exhaust portsD
injector nozzles
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For a given size engine, the two-stroke/cycle diesel engine will deliver more power than a four-stroke/cycle diesel engine because （）.A
it has a longer power strokeB
more air gets into the cylinder each strokeC
it develops twice as many power strokes at the same speedD
higher combustion pressure is developed
考题
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Fuel droplets injected into a diesel engine cylinder must have adequate penetration to （）A
prolong the ignition delay periodB
ensure the beginning of fuel injectionC
thoroughly utilize the air chargeD
allow controlled fuel combustion
考题
单选题The air required for combustion is taken from the engine room through a filter fitted on the turbochargerThis reduces the risk for too and contamination of the combustion air（）A
high temperaturesB
low temperaturesC
wetD
dirty
考题
单选题Diesel engines obtain combustion air through turbo chargers，blowers，or（）.A
air startersB
carburetorsC
natural aspirationD
air receivers
考题
单选题Compared to a naturally aspirated diesel engine, a supercharged diesel engine has（）A
a cylinder air charge of higher pressureB
increased pumping lossesC
less valve overlapD
reduced blow-by
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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