两种掺气水流的计算模型比较

在污水压力输送管道中，污水中气体的存在会影响液体的流动，以污水管中的气、液相流为研究对象，运用集中空穴模型（气泡离散分布模型）和均匀分布模型两种计算方法，来研究停泵水锤过程的压力和流速的变化趋势，实例计算结果表，在设有止回阀的水锤现象中，利用离散分布模型所得的最高水位要比利用均匀分布模型的计算值高，在不设止回阀的水锤现象中，两者的结构基本保持一致。均匀分布模型假定气体在水中呈均匀分布，因此在计算断面上的气体量变化不如离散分布模型来得剧烈，其水位正峰值比离散分布模型低，负峰值比离散分布模型高。

Comparison of Two Computed Air Entrainment Model

Air entrainment will change fluid pressure transients in sewage pumping stations. The changes of pressure and velocity under pump stoppage have been studied with two models-the air release model and the concentrated vaporous cavity model. The computed results indicated that with check valve the positive pressure peak of the concentrated vaporous cavity model was higher than that of the former one, but when check valve was not installed, the results of the two models have little difference. Because the air release model consumed the air in water distributed equably, compared with the concentrated vaporous cavity model, its upsurge was relative lower and the downsurge was relative higher.