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Across the expansion fan, the flow accelerates (velocity increases) and the Mach number increases, while the static pressure, temperature and density decrease. Since the process is isentropic, the stagnation properties (e.g. the total pressure and total temperature) remain constant across the fan.
static pressure + dynamic pressure = total pressure. This simplified form of Bernoulli's equation is fundamental to an understanding of the design and operation of ships, low speed aircraft, and airspeed indicators for low speed aircraft – that is aircraft whose maximum speed will be less than about 30% of the speed of sound .
is the static pressure at the point at which pressure coefficient is being evaluated is the static pressure in the freestream (i.e. remote from any disturbance) is the freestream fluid density (Air at sea level and 15 °C is 1.225 /)
When a centrifugal fan is specified for a given CFM and static pressure at conditions other than standard, an air density correction factor must be applied to select the proper size fan to meet the new condition. Since 200 °F (93 °C) air weighs only 80% of 70 °F (21 °C) air, the centrifugal fan creates less pressure and requires less power.
The air volume delivered by the centrifugal fan is not affected by density. However, since the 200°F air weighs much less than the 70°F air, the centrifugal fan will create less static pressure and will require less brake horsepower. When a centrifugal fan is specified for a given CFM and static pressure at conditions other than standard, an ...
An axial fan is a type of fan that causes gas to flow through it in an axial direction, parallel to the shaft about which the blades rotate. The flow is axial at entry and exit. The fan is designed to produce a pressure difference, and hence force, to cause a flow through the fan. Factors which determine the performance of the fan include the ...
In the case of an ideal lossless fan system (i.e. =) the SFP is exactly equal to the fan pressure rise (i.e. total pressure loss in the ventilation system). In reality the fan system efficiency is often in the range 0 to 60% (i.e. η t o t < 0.6 {\displaystyle \eta _{tot}<0.6} ); it is lowest for small fans or inefficient operating points (e.g ...
Water-cooling radiator transfers a lot of heat, and radiator fans have large static pressure (opposed to case fans that have high airflow) for dissipating heat. Laptop computers lack large openings in the case for warm air to escape. The laptop may be placed on a cooler – somewhat like a tray with fans built in – to ensure adequate cooling.