Convective Air Flow  Single Heat Source
Calculate the vertical air flow and air velocity generated by a single heat source.
A heat source, like an engine, stove, melting pot or a person, will generate a convective vertical air flow as indicated in the figure below.
Air Velocity
The air velocity in the center of the air flow at a distance above the floor can be calculated as
v_{c} = c_{1} (P / l)^{1/3} (1)
where
v_{c} = air velocity in center of the air flow (m/s)
c_{1} = constant characterizing the actual application, typical values ranging 1 to 2
P = heat power from the source (kW)
l = distance above the floor and the heat source (m)
Air Flow Volume
The air flow volume in a distance above the the floor can be calculated as
Q = c_{2} P^{1/3} l^{5/3} (2)
where
Q = air flow volume (m^{3}/s)
c_{2} = constant characterizing the actual application, values ranging 0.05 to 0.15 (typical 0.06)
Example  Convective Air Flow above an Engine
The heat loss from the surface of an engine is 10 kW. If c_{1} = 1.5, the air velocity 3 meters above the engine can be estimated to
v_{c} = 1.5 ((10 kW) / (3 m))^{1/3}
= 2.2 m/s
With c_{2} = 0.06 the volume flow can be estimated to
Q = 0.06 (10 kW)^{1/3} (3 m)^{5/3}
= 0.8 m^{3}/s
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