Reasonable selection of intake and exhaust diameters for air valve in water pipelines
The selection of inlet and outlet diameters for air valves in water pipelines,including low-pressure in-take and exhaust diameters for waterproof hammer type air valve,small exhaust diameter for buffer plate,and high-pressure micro exhaust diameter,not only affects the safety of water diversion project,but also seriously affects engineering investment.In order to reasonably select various types of air valve intake and exhaust diameters,this article first provides the functional relationship between the air volume flow rate and the flow coefficient,diame-ter,and air pressure,as well as the functional relationship between the water hammer pressure of the liquid col-umn bridging and the pipe diameter,the water hammer wave velocity,and the volume flow rate increment of the air valve.Then,the functional relationship between the air valve intake and exhaust diameters and the water filling and drainage flow rates,negative pressure control requirements and water hammer pressure are established,taking into account the influence of pipe stiffness and position elevation.Finally,taking the gravity flow water pipeline and the pump station pressurized water diversion pipeline as examples,the theoretical formulas obtained were applied to calculate and determine the intake and exhaust diameters of the composite air valve and the waterproof hammer type air valve,respectively.The results show that the intake and exhaust diameters of the air valves determined accord-ing to the formula in this article are not only much smaller than those determined by conventional experience,but can also effectively reduce the liquid column bridging water hammer pressure in the water pipeline.
air valveintake and exhaust diameterwater hammer pressurewater fillingdrainageaccident power failure
万方数据
维普
