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📢 | We will carry out the “first” online tour at a highway company! ~ [Home trip] Every time I explore Dorapura at home ...


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We will carry out the "first" online tour at a highway company! ~ [Home trip] Every time I explore Dorapura at home ...

 
If you write the contents roughly
◎ In this tour, you will visit an evacuation pit for emergencies such as accidents and tunnel fires, an underground ventilation center, an electric room, and a blower, which you cannot normally enter.
 

NEXCO East Japan and Hankyu Travel International Co., Ltd. jointly used the web conferencing system Zoom on September 9th (Saturday). → Continue reading

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Wikipedia related words

If there is no explanation, there is no corresponding item on Wikipedia.

Underground ventilation

Blower

BlowerWhat is (Sofuuki)?Feathercar'sRotational motionBygasToEnergygivemachineAnd the unitmassThe energy per hit is 25 kNmIt means less than / kg (kJ / kg).

Energy 25 kNm / kg per unit mass is about 30 k in the case ofPa Equivalent to (JIS B 0132: 2005 Blower / Compressor terminology).

Before the revisionJIS standardIn (JIS B 0132: 1984), a blower is a blower with a pressure ratio of less than 2, and a blower with a pressure ratio of 2 or more.CompressorAlthough it was classified as ISO, etc.International standardTo maintain consistency with2005(JIS B 0132: 2005 Explanation of terms for blowers and compressors).

Classification by pressure ratio (before revision)

Blowers are classified into fans and blowers according to the pressure ratio.

フ ァ ン

A fan is a blower with a pressure ratio of 1.1 or less.

Blower

A blower is a blower with a pressure ratio of about 1.1-2.liquidIt is used to blow gas into it.

(In the revised definition, blower is synonymous with fan, and blower isCompressorWas treated as)

Classification by format

Centrifugal blower

English name: Centrifugal Fan, which blows in the centrifugal direction.

Classification by structure

Multi-wing fan (sirocco fan)
A structure that combines a cylinder with a large number of small forward blades and a wind conditioner.Small, lightweight and inexpensiveFor consumerAt low rpmNormal temperatureBandwidth and large onesindustryHigh rotation and -50 for applications℃ -Can withstand + 500 ° CStrengthIt is widely used with.The air volume is smaller than other types of fans, but the static pressure can be increased.The static pressure efficiency is generally up to about 60%.
Backward fan (turbofan)
A single iron plate with rear-facing blades formed.Static pressure efficiency is about 1-65%.Depending on the manufacturer, it is made tough and is used when higher speed rotation is possible and high pressure is required.
Silent fan
The blades are S-shaped, the air inflow part is widened, and the suction port of the casing is widened like a bell mouth.There is relatively little noise even at high wind pressure.
Limit road fan
A combination of an inverted S-shaped blade and a curved vane so that the suction airflow is in the same direction as the blade.Even if the air volume increases, the shaft power does not increase above a certain level and is excessive.loadIt does not become.

Classification by blade shape

Airfoil fan (air foil blade)
A wing-shaped blade formed from two iron plates.
  • The static pressure efficiency for a multi-blade fan is about 65%.
  • Static pressure efficiency for limit road fans is 65-80%

Axial blower

A device that sucks air from the axial direction and blows air in the axial direction.ductIt can be installed in a small space on the way.It is possible to increase the air volume, and in the case of variable wings, efficiency is good even with partial load.

Diagonal blower

A rectifying plate that applies pressure in the diagonal direction of the suction shaft from the axial direction and changes the direction in the axial direction to blow air in the axial direction.It has properties intermediate between centrifugal and axial flow.

Cross flow blower (cross flow fan)

Also known as line flow fan, tangential fan (registered trademark), cross current fan, line deria (registered trademark), sweep fan, or once-through fan.An impeller that sucks in from one radial direction and blows air from a radial direction of about 90 ° (right angle).It is possible to obtain a uniform air volume, and it is easy to increase the length of the outlet while reducing the size, so it is an old-fashioned wall-mounted type.Air circulator, Wall-mounted air conditioner indoor unit fan, air curtain,Railway car,curtain wallIt is used for the slit type outlet of the part.The pressure cannot be high.

Field of application

ventilation

ventilationBlower used forVentilation fanThat.

Air conditioning

The generated airflow is mainlyAir conditioningBlower used for the purpose ofFanThat.

Fan motor

With fanselectric motorIs integrated.mainlymachine-Cooling of electrical equipment, Inside the device, etc.空 気It is used for circulation of.It is also used for local cooling by installing it in a specific place where high heat is generated.

ComputerThen.CPU,电源Installed in (CPU cooling device # air cooling),AutomobileThen.radiator[1],Air conditioncondenser, Air-cooledIntercooler[2]It is installed for cooling and ventilation of air conditioners.

More

Performance

An index showing the performance of the blower ispumpEtc.TurbomachinerySimilarly:

pressure
The pressure of the blower is expressed by the pressure difference between the suction port and the outlet.
Total pressure isStatic pressureとDynamic pressureSince it is the sum of and, it becomes as follows.
here,
PT: Blower total pressure
PT1: Stagnation pressure
PT2: Total spout pressure
PS: Blower static pressure
PS1: Suction static pressure
PS2: Outlet static pressure
PV1: Suction dynamic pressure
PV2: Discharge mouth dynamic pressure
Air flow
Axial power
Required to drive the blowerWork rate.
efficiency
Mechanical of fluid out of axial powerEnergyIt refers to the ratio converted to.Efficiency can be divided into mechanical efficiency, hydraulic efficiency, and volumetric efficiency.The loss is the loss due to mechanical friction, fluid friction and leakage, and ultimatelyheatIt is converted into energy and heats the fluid and the blower itself.

A graph representing these various performance valuesPerformance curveIs.In turbo type blowers, those that represent various performance values ​​by taking the air volume on the horizontal axis are often used.

theory

Law of proportionality

In the same blower, the air volume is proportional to the rotation speed, the pressure is proportional to the square of the rotation speed, and the shaft power is proportional to the cube of the rotation speed:

here,

  • Q: Air flow
  • P: Total pressure
  • W: Axial power
  • N: Rotation speed

Subscripts 1 and 2 indicate the values ​​before and after the rotation speed change, respectively.

Furthermore, a similar law of proportionality holds for similar blowers,modelIt is the basis for conducting experiments using.

Blower components

footnote 

  1. ^ Vertical engineThen.CrankshaftThe method of driving the fan with a pulley and a fan belt is still the mainstream.
  2. ^ A top-mounted intercooler to compensate for the lack of cooling air flow at low speeds.

References

  • "Turbomachinery Association", "Introduction to Turbomachinery, New Revised Edition", Nihon Kogyo Shuppan, 2011.ISBN 978-4-8190-1711-4. 

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