Research On The Influence Of Inertia Of Pump Unit To Water Hammer

In the long distance water supply pipe construction project, water hammer accident is prevalent phenomenon especially in the projects of complex terrain and elevation. Pump unit is an important part of long-distance water delivery system,and the transient of the pump after it's stopping have a direct influence to the hydraulic transition process of pipeline, therefore, the characteristics of pump unit is an important boundary conditions for water hammer computation.Researching the effect of the pump inertia for water hammer has theoretic value and practical significance to water hammer protection,because rotational inertia is one of an important characteristics of pump unit.In the thesis, we introduced the "Method of characteristics" of water hammer computation and its application systematically based on momentum equations of water hammer computation, and also represent the pump unit's border control conditions when using the "Method of characteristics" for water hammer computation.According to water-hammer's characteristics, we analyzed the effects of changging pump inertia to the pump water hammer pressor, and introduced several normal equipment for water hammer protective in practical projects and all its'boundary control conditions simply.The thesis expounds measures for increasing pump inertia frequently-used in practical projects, discussed the characteristics of inertial flywheel, dimension design and installation. Reviewed its motors'start torque and computing start-up time for pump unit of installed inertial flywheel.This paper selects two water engineering examples, including a project example of lesser pump inertia, and the other is larger. On the condition of using hydraulic slowly-closing check valve and buffer vent in pipeline, study on the rotational inertia of the pump unit to water hammer influence utilize the results of water hammer calculation and the pump unit transient data after changging its'inertia. Calculate the size of inertial flywheel and start-up time of pump unit, analysis the feasibility of thickening outfit inertial flywheel.As to the pump unit has smaller inertia originally, the theoretical analysis and engineering example is also given that enlargement pump inertia suitable can effectively relieve water hammer pressurization, and whether using replacing motor or increase outfit inertial flywheel to increase the rotational inertia of the pump unit is convenient and feasible. For the pump unit has larger inertia originally, increase the rotational inertia can also relieve and even complete control water hammer pressurization, but the sizes of inertial flywheel is must be very large,no matter design manufacturing or large installation are very difficult, not even can be implemented. Therefore, the method of increasing the pump rotational inertiafor water hammer protect only applies to the delivery pipe line has smaller pump unit capacity.