produce the heat for ignition
decrease injection lag
increase ignition delay
aid in exhausting burnt gases
第1题：
_______is usually driven by the engine camshaft and supplies pilot air to the cylinder air start valve.
A.An air receiver
B.An operating valve
C.An automatic valve
D.An air distributor
第2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 cylinder
B.Excessive fuel in the cylinder
C.Excessive air in the cylinder
D.Spark ignition
第3题：
Diesel engines are started by supplying into the cylinders in the appropriate sequence for the required direction.
A.cooling water
B.compressing air
C.compressed air
D.cylinder oil
第4题：
to inspect if the cylinder has the water leakage
to expel out the residual water/gas/oil from the cylinder
to check if fuel supply is normal
A and B
第5题：
What is the most probable cause of reduced capacity in a reciprocating air compressor ________．
A.Carbon on cylinder heads
B.Faulty unloader
C.Leaking air valves
D.Plugged air cooler
第6题：
In an operating diesel engine, which of the following conditions is an indication of a leaking air starting valve?
A.Noise coming from that air starting valve
B.Continuous operation of the starting air compressor
C.Zero air pressure in the air starting system
D.Overheated starting air pipe to the cylinder head
第7题：
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
第8题：
Diesel engines are started by supplying_____into the cylinders in the appropriate sequence for the required direction.
A.cooling water
B.compressing air
C.compressed air
D.cylinder oil
第9题：
the starting air distributor
the cut-off valve on the air main
the main starting valve
the air bottle control valve
第10题：
blows out the exhaust gases
supplies oxygen for combustion
cools the valves and cylinder walls
all of the above