题目内容（请给出正确答案）

[主观题]

In each cylinder cover there are two or three holes for（）

A．the exhaust valves

B．the fuel valves

C．indicator cocks

D．the fuel pum

查看答案

如搜索结果不匹配，请联系老师获取答案

您可能会需要：

重置密码查看订单联系客服

安装赏学吧APP，拍照搜题省时又省心！

更多“In each cylinder cover there a…”相关的问题

第1题

The main factor which determines the output of each cylinder is _____.A.the cylinder weigh

The main factor which determines the output of each cylinder is _____.

A.the cylinder weight

B.the cylinder bore

C.the cylinder length

D.the cylinder cover

点击查看答案

第2题

Each cylinder liner on the marine medium speed engines _____.A.is usually cooled by sea wa

Each cylinder liner on the marine medium speed engines _____.

A.is usually cooled by sea water

B.can be replaced when worn out

C.is in direct contact with the water in the bore of the cylinder

D.can t expand when heated

点击查看答案

第3题

Each cylinder is closed at the top by a _____, made of a special heat-resistant steel.A.cy

Each cylinder is closed at the top by a _____, made of a special heat-resistant steel.

A.cylinder liner

B.coupling flange

C.cylinder cover

D.piston crown

点击查看答案

第4题

In a diesel engine, late fuel injection is indicated by black or gray exhaust smoke with _

_____.

A.low firing pressure

B.low exhaust temperature

C.mechanical knock in each cylinder

D.fuel knock in each cylinder

点击查看答案

第5题

By comparing the exhaust gas temperature of each cylinder, the operator can determine if t

he load is balanced throughout the engine The device most commonly used is a

A.tachometer

B.pyrometer

C.dynamometer

D.calorimeter

点击查看答案

第6题

During the fuel injection period, fuel pressure must exceed cylinder gas pressure to（）

A．ensure penetration and distribution of the fuel in the combustion chamber

B．ensure the needle valve is flushed clean during each injection

C．prevent combustion gas blowback into the open needle valve

D．prevent reflected pressure waves when the needle valve close

点击查看答案

第7题

第一组： The Wartsila 50DF operates on the lean-bum principle: the mixture of air and gas i

n 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

点击查看答案

第8题

已知随机变量X, Y, Z的协方差Cov（X, Z)=2，Cov（Y, Z)=1，则 Cov（X+Y, 3Z)=

A.2

B.3

C.6

D.9