Water Hammer Analysis for Heated Liquid Transmission Pipeline with Entrapped Gas Based on Homogeneous Flow Model and Fractional Flow Model

In view of the hydraulic transient problem in heated liquid pipeline with entrapped gas, water hammer analysis equations are built. The solve methods are discussed based on homogeneous flow model and fractional flow model. Then VC++ is utilized to develop a computer program to simulate the hydraulic transient behavior. Ultimately, this paper simulates the hydraulic transient behavior on the conditions which include different initial void fraction in liquid, a constant liquid level at upstream end and sudden closure of valve at downstream end of pipeline. The simulation results not only suggest higher void fraction in liquid lead to lager of water hammer wave response, lower of fluctuation frequency and quicker of pressure wave damping but also indicate small amount of gas in liquid can weaken pressure increasing caused by water hammer. At the same time, the differences between the two models´ simulation results are analyzed, the analysis shows that fractional flow model is better than homogeneous flow model if liquid column separation phenomenon occurs. The study results are benefit to guide the hydraulic transient problem in practical.