Study Of Water Hammer Protection And Numerical Simulation Of Sudan Long-distance Water Transmission Pipeline Project

With our country’s rapid economic development, the overseas construction project has been increasing year by year, especially the water supply engineering in Africa. In Africa, the long-distance water diversion is carried out subject to its vast and sparsely populated area. In the long-distance water diversion engineering, at pump starting and stopping, the water bump occurs when a series of suddenly pressure variation in the pipeline caused by flow velocity dramatically changed. This phenomenon is called water hammer. The pipeline will burst or be crushed due to the excessive positive or negative pressure. It will cause the serious damages and economic losses. Therefore, to ensure the health of the water tra nsmission system, it is crucial to formulate the reasonable and reliable water hammer protection scheme, taking the appropriate water hammer protection.The article is based on the practical problem caused by water hammer in Sudan long-distance water diversion engineering, determine the type of water hammer probably occur by steady state calculation and hammer analysis and take the water hammer of cavities collapsing caused by pump failure as the principal protection target. According to the engineering characters, combined with the merit and demerit of various water hammer prevention measures and units, the pump control valve and air valve are installed for water hammer protection to the engineering.The closing time of slow closing check valve is varied from the form of the pipeline. Numerical simulation analysis is conducted by the software in this study to determine the closing plan of slow closing check valve which is as a basis of further air valve arrangement.In traditional experience, proved by numerical simulation analysis, arrangement of normal air valve functioned with rapid exhaust didn’t improve the high pressure at the check valve after pump and negative pressure along the pipeline, which did not meet the requirements of water hammer protection.In order to improve such problem, water hammer protection type air valves are installed instead of ordinary air valves. It is found from the numerical simulation analysis that water hammer protection type air valve can effectively cut down Cavities Collapsing Water Hammer. Positive pressure water hammers are almost eliminated and negative pressure water hammers are basically improved when water hammer protective type air valves are installed all way along. In addition, the maximum pressure at the check valve meets the requirements of specification which achieve the requirements of water hammer control.However, water hammer protection type air valve is much expansive than ordinary air valve, so using water hammer protection type air valve all way along is not rational due to the large investment. Water hammer protection plan should be optimized as much as possible. Through simulation study point by point, ordinary exhaust valve should be set on the point with small air inflow, water Hammer Protection air valve should be only set on the large air inflow point. Ultimately, an appropriate water hammer protection scheme for the long-distance water diversion is proposed and verified in actual operation by the pressure test to achieve the protective effect on controlling the column separation water hammer.The article analyzes the technique and economic on the improved water hammer protection scheme, shows the scheme can either improve the water hammer protection, or bring the economic benefit with lower investmen t, giving an advisable reference to study on the water hammer protection in long-distance water diversion engineering.