How does hammer calculate flow rate of air through the air valve element?
To compute the flow rate of air through the air valve element, HAMMER uses the following equation: where Po is the density of air at 4°C and 1 atmosphere (=1.293 g/l), S=0.6A, with A being the cross-sectional area of the orifice. The throttling of air flow due to the “sonic velocity” is automatically calculated using the above formulation. where Y is the exponent in the gas law, p is the absolute pressure, the subscript 0 denotes standard conditions, and p/py = constant. For air inflow, (1) is again applicable, except that the ratio within the square brackets is inverted to be p/p0 as p0>p in this instance. the exponent, Y, in the gas law is hard-coded as 1.4, which corresponds to adiabatic compression/expansion appropriate for the typically rapid processes which occur.
