A Method for Determining the Time-Dependent Pressures in a Series of Chambers Connected to an External Pressure Whose Variation with Time is Known

A method is presented for the determination of the time dependent pressure in a series of chambers interconnected by orifices with the first chamber subjected to an external pressure whose variation with time is known. The equations describing this problem have been solved numerically utilizing a digital computer. Comparisons of the results obtained from the computer solution with experimental data are also presented. For the special case of a single volume a nondimensional parameter is obtained which, in conjunction with a given external pressure, completely defines the flow. This parameter is used to provide a set of curves which can be used to estimate the maximum pressure differentials which a spacecraft containing a single volume will encounter when subjected to a typical launch vehicle ambient pressure profile. In addition the realm of applicability of incompressible theory to the venting of a single chamber is determined in terms of the nondimensional parameter. Also included is an, analysis of venting of a single chamber through a long channel where viscous effects become important.