TRANSITION OF GRAVITY TO SURCHARGED FLOW IN SEWERS.

This Thesis deals with transients that occur when gravity flow is suddenly changed to pressure flow by the occurrence of a surge in the form of a travelling hydraulic jump in the line. The pressure head fluctuations associated with this transient have been studied. The transition is complicated by the mixture of air and water in the pipe. The transients in this two-phase air-water flow have been considered in this study. Some of the factors affecting these pressure transients are: pipe size, pipe shape, flow velocity, Froude number, relative depth of flow, alignment of the pipe, pipe material, venting arrangements and boundary conditions such as pumps, interceptors, and drop pipes. A mathematical model is developed to describe the mechanics of surcharging of a sewer; the model predicts the surge velocity, the surcharge at the surge front relative to sewer crown, the water level in the sump well or manhole, the velocity of the water surface in the sump well, the distance travelled by the surge front and, the transient pressure rise in the air-water two-phase flow. The mathematical model results are compared with the experimental results from the present study. The mathematical model results are in general agreement with the experimental data but the experimental pressure fluctuations were approximately 50% of the theoretical predictions. The random nature of the instability of the air-water interface and the extent of the blockage contributed to disagreement between the theory and the model prediction.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1982 .H263. Source: Dissertation Abstracts International, Volume: 43-03, Section: B, page: 0807. Thesis (Ph.D.)--University of Windsor (Canada), 1982