EXPERIMENTAL AND ANALYTICAL INVESTIGATION OF ENTRAPPED AIR IN A HORIZONTAL PIPE

摘要

In this paper analytical and experimental results are presented for pressurizing isolated pockets of air at the end of a water column in a horizontal pipeline. The analytical phase addresses issues such as (1) effect of elasticity of water column, (2) variation of length of water column during the transient, and (3) thermodynamic processes during compression and expansion of gas pockets. The analysis shows that many entrapped air problems in liquid systems are principally governed by the liquid inertia and the gas elasticity, with the latter considered as a lumped quantity. However, laboratory experiments coupled with both inelastic and elastic liquid behavior have shown that, for severe cases of pressurization, wave propagation in the liquid medium needs to be considered. Analytical results are presented demonstrating the range of application of inelastic liquid (rigid column) and lumped gas behavior.