Page 244 - 48Fundamentals of Compressible Fluid Mechanics

206CHAPTER 12. EVACUATING/FILING CHAMBERS UNDER EXTERNAL VOLUME CONTROL
12.1.3 Direct Connection

In the above analysis is applicable to indirect connection. It should be noted that
, is not function of the time. The direct connection posts more math-
ematical difficulty because the critical area is not constant and time dependent.
To continue
@
12.2 Summary
critical area,
The analysis indicates there is a critical vent area below which the ventilation is
poor and above which the resistance to air flow is minimal. This critical area de-
pends on the geometry and the filling time. The critical area also provides a mean
to “combine” the actual vent area with the vent resistance for numerical simulations
of the cavity filling, taking into account the compressibility of the gas flow.