The working principle of air volume and air pressure in [cooling fan]
The working principle of air volume and air pressure in [cooling fan]
u003cbru003e Air volume and wind pressure: There are two test methods for air volume and wind pressure, one is to test with wind tunnel instrument, the other is to test with double box method. But for the average user, there is no such device. The data provided by the manufacturer can only be used as a reference, and the cooling effect will ultimately depend on. Air volume refers to the product of the plane speed of the fan's ventilation area. The ventilation area is the product of the exit area minus the projection of the vortex tongue. The plane velocity is the gas velocity of the air flow through the entire plane, in m3/s. When the plane speed is constant, the larger the outer diameter of the fan blade impeller, the larger the ventilation area, and the larger the air volume. The plane speed is determined by the rotation speed and wind pressure of the rotor. When the ventilation area is constant, the greater the plane speed, the greater the air volume, the greater the heat absorption of the air, the more heat can be taken away when the air moves, and the greater the fan heating effect obvious. In order to perform normal ventilation, it is necessary to overcome the resistance in the fan's ventilation stroke. The fan must generate pressure to overcome the air supply resistance. The measured pressure change value is called static pressure, which is the differential pressure between the maximum static pressure and the atmospheric pressure. It is the pressure exerted by the gas on the surface parallel to the object, and the static pressure is measured through a hole perpendicular to the surface. Converting the kinetic energy required in the gas flow into a pressure form is called dynamic pressure.
u003cbru003e In order to achieve the purpose of air supply, static pressure and dynamic pressure are required. The total pressure is the algebraic sum of the static pressure and the dynamic pressure. The total pressure refers to the total pressure increase given by the fan, that is, the total pressure difference between the outlet and the inlet of the fan. In practical applications, the nominal maximum air volume value is not the air volume obtained by the actual fan heater. Large air volume does not mean strong ventilation capacity. When the air flows, the airflow will encounter the obstruction of the fan heat sheet or components in its flow path, which will restrict the free circulation of air, that is, when the air volume increases, the wind pressure will decrease. Therefore, there must be an optimal operating point, that is, the intersection of the fan performance curve and the wind resistance curve. At the operating point, the slope of the fan characteristic curve is the smallest, and the change rate of the system characteristic curve is the smallest. Note that the static efficiency of the fan (air volume × air pressure ÷ power consumption) is the best at this time. Of course, sometimes in order to reduce the system impedance, even a smaller size fan can be used to obtain the same air volume.
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u003cbru003eRelated links:
u003cbru003eCar cooling fan http:///products-detail.asp?cpidu003d121
u003cbru003eCar radiator fan http:///products-detail.asp?cpidu003d123
