单选题The fresh air coming in through the inner air ports, is compressed by（） to a higher pressure.A the cylinder headB the cross-headC the moving pistonD the stationary piston

题目
单选题
The fresh air coming in through the inner air ports, is compressed by（） to a higher pressure.
A

the cylinder head

B

the cross-head

C

the moving piston

D

the stationary piston

相似考题

1.In Leon Nacson’s view, air and water are our Number One priorities for the following reasons except ().A、he cannot understand why people are polluting air and waterB、there will definitely be no fresh air and clean water for future generationsC、we would run out of air and water if we didn’t stop polluting themD、air and water polluting are the current and futu

2.第二组Under normal operation, some lubrication oil mist may be discharged from the air compressor to the air start system. This oil may be from excess compressor cylinder lubrication, from faulty oil scraper rings, or may even be suspended oil vapor contaminating the engine room atmosphere and drawn in at the compressor suction. Oil discharge is kept to a minimum by draining the after cooler, air receiver and starting system. If small quantities of lubrication oil do get passed into the starting air system, they will deposit as thin moist film over internal pipe surfaces but are not readily combustible. If a cylinder non-return valve leak while the engine is in operation, some hot gas, possibly with unburned fuel and cylinder lubrication oil, may be blown through the valve to the adjacent air manifold. With further heating from the leaky valve, this, together with the already deposited oil film, will carbonize and form. incandescent carbon. If starting air is applied to the system while still hot, the high pressure air coming into contact with the burning carbon may cause an explosion. Such an explosion will cause a flame to pass back through the air start pipe system, evaporating the deposited oil film and igniting it in the presence of air. Very high velocities and shockwaves are generated which may rupture pipes and fittings.Alternatively, if excessive oil has entered the air start system, a mixture of air and oil droplets may be discharged through the open cylinder non-return valve during starting. This spray may ignite due to high temperatures in the cylinder, causing a flame through the still open valve to the air manifold.To prevent an explosion, air start valves must be correctly maintained and lubricated to ensure correct timing and free movement with positive closing. Oil in the system must be kept to a minimum, pipe lines must be drained and cleaned internally when necessary and oil discharge from air compressors must be kept to a minimum by good maintenance.The passage is mainly aboutA.crankcase explosionB.scavenge box fireC.starting air pipeD.the danger of explosion in the starting air system

3.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 valveB.Continuous operation of the starting air compressorC.Zero air pressure in the air starting systemD.Overheated starting air pipe to the cylinder head

4.Ventilation ().A、is a system for moving fresh airB、can cut indoor pollution to a safe levelC、can cause some diseasesD、is better done through air-conditioning

更多“The fresh air coming in through the inner air ports, is comp”相关问题

  • 第1题：

    Diesel engines obtain combustion air through turbo chargers，blowers，or ______．

    A.Air starters

    B.Carburetors

    C.Natural aspiration

    D.Air receivers


    正确答案：C

  • 第2题：

    If headaches only occur at night,lack of fresh air is often the cause.

    A:start
    B:begin
    C:happen
    D:visit

    答案：C
    解析：

  • 第3题：

    The （）(天窗) admits light and fresh air through.

    • A、skylight
    • B、bulwark
    • C、keel
    • D、bulkhead

    正确答案:A

  • 第4题：

    单选题
    The process of loop scavenge is that the exhaust will be via ports （） the air ports and controlled by the same piston.
    A

    behind

    B

    far from

    C

    adjacent to

    D

    in front of


    正确答案： A
    解析： 暂无解析

  • 第5题：

    单选题
    Which of the following methods is used to prevent throttling of compressed air through the diesel engine air starting valves?（）
    A

    Holding the valve open for a long period

    B

    Increasing the starting air pressure used

    C

    Opening the stating air valve quickly

    D

    Reducing the starting air valve size


    正确答案： D
    解析： 暂无解析

  • 第6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 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


    正确答案： B
    解析： 暂无解析

  • 第7题：

    单选题
    Gas exchange, which is a basic part of the cycle of an internal combustion engine, is（）
    A

    the supply of normal air and removal of compressed air

    B

    the supply of fuel oil and combustion of the atomized oil

    C

    the supply of fresh air and removal of exhaust gases

    D

    the supply of fresh air and removal of the extra heat


    正确答案： B
    解析： 暂无解析

  • 第8题：

    单选题
    Most air conditioning units have （） for adjusting the ratio of recirculated fresh airCare must be taken not to reduce the fresh air so that stuffiness or smells arise.
    A

    catch plates

    B

    dampers

    C

    regulating valves

    D

    fans


    正确答案： B
    解析： 暂无解析

  • 第9题：

    单选题
    Starting air for auxiliary engines may be taken directly from the main reservoirs or through （）.
    A

    an auxiliary reservoir

    B

    a controlling air bottle

    C

    an emergency air compressor

    D

    a main air compressor


    正确答案： B
    解析： 暂无解析

  • 第10题：

    单选题
    Directional intake ports in diesel engines are used to （）.
    A

    reduce air charge turbulence

    B

    induce air swirl

    C

    deflect hot combustion gas away from the valves

    D

    oppose the effects of piston induced squish


    正确答案： B
    解析： 暂无解析

  • 第11题：

    单选题
    In a two-stroke engine, there are always a series of openings known as （）, and in some circumstances, there are also openings known as （）, in the part of the cylinder liner.
    A

    scavenging air ports；exhaust ports

    B

    inlet ports；scavenging air ports

    C

    scavenging air ports；inlet ports

    D

    exhaust ports；inlet ports


    正确答案： A
    解析： 暂无解析

  • 第12题：

    单选题
    The air distributor is conventionally driven by（） and distributes into each cylinder by（） certain sequence.
    A

    camshaft；fresh air

    B

    camshaft；starting air

    C

    electronic motor which is controlled by a computer；fresh air

    D

    electronic motor which is controlled by a computer；starting air


    正确答案： D
    解析： 暂无解析

  • 第13题：

    _______there is fresh air, there is oxygen.

    A．Wherever
    B．Whenever
    C．Unless
    D．Whether

    答案：A
    解析：
    考查地点状语从句。句意为“凡是有空气的地方，就有氧气”。这里wherever表示无论哪里的意思，其他选项都不符合逻辑。

  • 第14题：

    Heating，ventilating，and air conditioning（HVAC） systems are______in most of underground subway stations to provide comfortable and fresh air to underground subway stations。

    A.assembled
    B.installing
    C.equipped
    D.installed

    答案：D
    解析：
    本题考查动词的词义辨析。题目意为“大多数地下地铁车站都安装了供暖、通风和空调系统，为地下地铁车站提供舒适和新鲜的空气。”A选项“装配，集合”，B选项“安装”，C选项“装备”， D选项“（被）安装”。由于主语是物，和动词“安装”之间构成被动关系，因此要选择“（被）安装”。
    　　

  • 第15题：

    We should take （）to keep the chemicals away from fire.

    • A、great care
    • B、some measures
    • C、fresh water
    • D、fresh air

    正确答案:B

  • 第16题：

    单选题
    （） is the removal of exhaust gases by blowing in fresh air.
    A

    Gas exchange

    B

    Charging

    C

    Scavenging

    D

    Supercharging


    正确答案： D
    解析： 暂无解析

  • 第17题：

    单选题
    The compressed air is admitted to each cylinder through a cam operated by starting air valve when the piston has just passed its （）.
    A

    BDC

    B

    TDC

    C

    BBDC

    D

    ATDC


    正确答案： A
    解析： 暂无解析

  • 第18题：

    单选题
    Scavenging is （） of exhaust gases by blowing in fresh air.
    A

    the suction

    B

    the compression

    C

    the removal

    D

    the deliver


    正确答案： A
    解析： 暂无解析

  • 第19题：

    单选题
    In the starting system, the automatic valve is controlled by（）, and the cylinder start valves are controlled by（）
    A

    pilot air；pilot air

    B

    handle；solenoid

    C

    handle；pilot air coming through the distributor

    D

    solenoid；pilot air coming through the distributor


    正确答案： B
    解析： 暂无解析

  • 第20题：

    单选题
    What is the passage mainly about?
    A

    How to fight air pollution in big cities.

    B

    How to avoid air pollution in big cities.

    C

    How to breathe fresh air in big cities.

    D

    How serious air pollution is in big cities.


    正确答案： B
    解析：
    第一段第四句是全文的主题句：城市人如何减少接触被污染的空气。

  • 第21题：

    单选题
    Which of the following methods is normally used to control the temperature of air distributed from individual cooling coils in an air conditioning system using a chilled water circulation system?（）
    A

    A room thermostat activates an electric heater at each individual chilled air outlet when necessary

    B

    Varying the number of passes the air makes across the coils

    C

    Varying the temperature of the water through the coils

    D

    Varying the quantity of water flowing through the coils


    正确答案： B
    解析： 暂无解析

  • 第22题：

    单选题
    To prevent the unnecessary loading of an air conditioning system while maintaining the designed dry bulb temperature and relative humidity in an air conditioning system, you should （）
    A

    admit only enough fresh outside air to provide proper ventilation

    B

    reduce the air reheating system load

    C

    lower the compressor head pressure

    D

    operate the purge recovery unit continuously


    正确答案： C
    解析： 暂无解析

  • 第23题：

    单选题
    In an operating diesel engine, which of the following condition 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


    正确答案： B
    解析： 暂无解析

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