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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 reality the fan system efficiency is often in the range 0 to 60% (i.e. <); it is lowest for small fans or inefficient operating points (e.g. throttled flow or free-flow). The efficiency is a function of the total losses in the fan system, including aerodynamic losses in the fan, friction losses in the drive (e.g. belt), losses in the ...
A balanced or neutral airflow is the most efficient, although a slightly positive airflow can result in less dust build up if filtered properly Heat pipes A heat pipe is a heat transfer device that uses evaporation and condensation of a two-phase "working fluid" or coolant to transport large quantities of heat with a very small difference in ...
Free air flow is the amount of air a fan will move with zero back-pressure. Maximum differential pressure is the amount of pressure a fan can generate when completely blocked. In between these two extremes are a series of corresponding measurements of flow versus pressure which is usually presented as a graph.
The affinity laws (also known as the "Fan Laws" or "Pump Laws") for pumps/fans are used in hydraulics, hydronics and/or HVAC to express the relationship between variables involved in pump or fan performance (such as head, volumetric flow rate, shaft speed) and power. They apply to pumps, fans, and hydraulic turbines. In these rotary implements ...
A new parameter, effective Air Changes per Hour (called ACHH by Mojtaba Zabihi et. al. [8]), which incorporates both the flow rate and large-scale airflow patterns, could provide a more accurate measure of how efficiently air is supplied and circulated within a room. This is particularly important for effectively managing airborne disease spread.
Induced flow fans are housed fans whose outlet airflow is greater than their inlet airflow due to induced airflow. They are generally used in laboratory or hazardous atmosphere exhaust applications. ANSI/AMCA Standard 300 - Reverberant Room Method for Sound Testing of Fans applies to fans of all types and sizes. It is limited to the ...
The bypass ratio (BPR) of a turbofan engine is the ratio between the mass flow rate of the bypass stream to the mass flow rate entering the core. [1] A 10:1 bypass ratio, for example, means that 10 kg of air passes through the bypass duct for every 1 kg of air passing through the core.