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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 process
B
forcing the products of combustion out of the cylinder with the fresh air charge
C
collecting the air charge at the cleaner
D
combustion and expansion of hot gas
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更多 “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” 相关考题
考题
A two stroke diesel engine exhaust temperature will be lower than a four stroke diesel engine of the same displacement because the _____. ① MEP is lower and the scavenging air is cooling the exhaust gases ② valve overlap in a four strokeA.①B.②C.① and ②D.Neither ① nor ② is correct
考题
Which of the following conditions could contribute to the cracking of a diesel engine cylinder head?A.Leaking seal ringB.Insufficient heat transfer from the exhaust valvesC.Blocked cooling water passages to the headD.Excessive scavenging air provided to the engine
考题
During the valve overlap period, the exhaust pressure of a turbocharged four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure ______.A.effective cylinder scavenging and coolingB.constant pressure from the turbochargersC.cooler operation of the exhaust systemD.effective constant pressure for turbocharger operation
考题
If you are unable to stop a diesel engine by any other means，you should ______．A.Discharge a CO2 extinguisher in the air inletB.Pull off the distributor capC.Secure the jacket waterD.Secure the starting air supply valve
考题
单选题The marine diesel engine is a type of diesel engine used on ships The （） of its operation is not very difficult to understand.A
principleB
principalC
causeD
case
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Diesel engine jacket water is used in the distillation process as the （）.A
coolant for the distillateB
coolant for the brine coolerC
means of heating the feedwaterD
primary means of producing a vacuum within the distiller
考题
单选题Which of the following conditions could contribute to the cracking of a diesel engine cylinder head?（）A
Leaking seal ringB
Insufficient heat transfer from the exhaust valvesC
Block cooling water passages to the headD
Excessive scavenging air provided to the engine
考题
单选题Why are some diesel engine cylinder liners plated on the wearing surface with porous chromium?（）A
The chromium will not wear out the piston ringsB
The chromium strengthens the liners in the way of the scavenging air portsC
Chromium eliminates the need for oil scraper ringsD
Pores in the plating aid in maintaining the lube oil film
考题
单选题A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) MEP is lower and the scavenging air is cooling the exhaust gases (2) valve overlap in a four-strokeA
(1) only is correctB
(2) only is correctC
both (1) and (2) are correctD
Neither (1) or (2) are correct
考题
单选题The size of the exhaust valve opening is （）A
most critical in a four-stroke cycle diesel engineB
most critical in a two-stroke/cycle diesel engineC
most critical in a four-stroke/cycle diesel engine if it is turbochargedD
of equal importance in a two-stroke/cycle diesel engine as in a four-stroke/cycle diesel engine
考题
单选题In describing basic diesel engine operation，the term ‘event’ refers to （）A
the production of high pressure gasesB
the removal of expended combustion gasesC
the admission of air to the cylinderD
all of the above
考题
单选题If you are unable to stop a diesel engine by any other means，you should（）.A
discharge a CO2 extinguisher in the air inletB
pull off the distributor capC
secure the jacket waterD
secure the starting air supply valve
考题
单选题During the valve overlap period, the exhaust pressure of a turbochargers, four-stroke/cycle diesel engine must be less than the intake manifold pressure to ensure （）A
effective cylinder scavenging and coolingB
constant pressure from the turbochargersC
cooler operation of the exhaust systemD
effective constant pressure for turbocharger operation
考题
单选题"Scavenging" on a diesel engine means （）.A
injecting fuel oil into a cylinderB
removing exhaust gases from the cylinderC
forcing air into the cylinders under pressure after the exhaust valve has dosedD
a combination of all the above
考题
单选题Proper lubrication of the main bearing is more easily obtained in a single acting four-stroke/cycle diesel engine than in a single acting two-stroke/cycle diesel engine because （）A
bearing pressure in a four-stroke/cycle acting single diesel engine is continually reversedB
bearing pressure in a two-stroke/cycle single acting diesel engine is continually reversedC
the maximum bearing pressure is higher in a single acting two-stroke/cycle diesel engineD
two-stoke/cycle diesel engines require more complicated lubrication piping
考题
单选题Scavenging in a four-stroke/cycle diesel engine occurs during the （）.A
last part of the exhaust stroke, and the first part of the intake strokeB
last part of the intake stroke onlyC
early part of the injection stroke onlyD
early part of the power stroke
考题
单选题Clearance volume scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished （）.A
during the valve overlap periodB
with only the exhaust valve openC
at a pressure below atmosphericD
without cooling the cylinders or pistons
考题
单选题The exhaust ports of a diesel engine using the cross-flow scavenging method are opened and closed by the （）A
reciprocating motion of exhaust valvesB
rotary motion of the camshaftC
reciprocating motion of the pistonD
developed differential
考题
单选题Any increase in the exhaust back pressure of a four-stroke/cycle diesel engine will （）.A
reduce engine horsepower outputB
aid in silencing the exhaust noiseC
increase the mean effective pressureD
contribute to effective cylinder scavenging
考题
单选题The process of scavenging a two-stroke/cycle diesel engine serves to（）A
improve fuel flow volumeB
cool the exhaust valvesC
reduce the intake air charge densityD
increase the temperature of exhaust gases
考题
单选题The principal difference between loop scavenging and crossflow scavenging, as used in single acting diesel engines, is the （）A
direction of air flow within the cylinderB
sequence of port openingC
method of opening exhaust portsD
volume of air admitted to the cylinder
考题
单选题The term medium speed diesel engine is currently taken to mean an engine with an operating rotational speed of （） rpm.A
below 300B
above 1200C
between 300 to 1200D
below 1200
考题
单选题Scavenging in a turbocharged, four-stroke/cycle diesel engine is accomplished（）A
during the valve overlap periodB
with only the exhaust valve openC
at a pressure below atmosphericD
without cooling the cylinders or pistons
考题
单选题In a diesel engine, an extremely leaking exhaust valve can cause （）.A
misfiringB
pre-ignitionC
interrupted scavengingD
reduced scavenging
考题
单选题The camshaft on a four-stroke/cycle diesel engine provides a means to operate the （）.A
fuel injectorsB
exhaust valvesC
intake valvesD
all of the above
考题
单选题A two-stroke diesel engine exhaust temperature will be lower than a four-stroke diesel engine of the same displacement because the （） (1) scavenging air is cooling the exhaust gases (2) exhaust cycle time is longerA
(1) onlyB
(2) onlyC
both (1) and (2)D
neither (1) nor (2)
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