Like a breach in a spacecraft?
How can I calculate the wind speed and rate of air loss moving through a hole, given the pressure differential, size of the hole, size of the air source, size of the air sink, temperature, etc.?
2007-03-27 15:42:55 · 2 answers · asked by anonymous 4 in Science & Mathematics ➔ Physics
This is a more difficult question than you realize. The airflow is dependent on a number of factors including the shape of the hole and the composition of the edges of the hole - sharp, rounded, jagged, etc. all affect airflow. For air, discharging into a vacuum, there is no "downstream pressure" and the air flow will be under CRITICAL FLOW CONDITIONS, that is, the linear velocity of the air at the throat equals the speed of sound in the air at that location. Under these conditions, the airflow can be approximated as:
w = 0.533CAp/sqrt(T)
where:
w = flowrate, lb/sec
C = the coefficient of discharge of the hole, dimensionless (see below)
A = cross-sectional area of the throat, not the same as the hole size but can use hole size as an approximation, ft²
p = pressure upstream of the hole, lb-force/ft²
T = temperature of air upstream of the hole, °R (°F + 460)
Coefficient of discharge for a given hole is a function of Reynolds Number. For discharge from moderate air pressure into a vacuum, the Reynolds Number will be quite high, so the coefficient of discharge will be fairly constant. For most holes discharging to vacuum, the value of C will probably be in the range of 0.6 to 0.7.
2007-03-27 16:05:15 · answer #1 · answered by CheeseHead 2 · 1⤊ 0⤋
it hurts my brain to even think about this ! you want some kind of freakin' calculus cr@p !
2007-03-27 15:48:31 · answer #2 · answered by Scorpius59 7 · 0⤊ 0⤋