Research On Decompression Performance And Hydraulic Characteristics Of An Adjustable Fences Pressure-relief Device

It is a common phenomenon for the existing buildings to have surpluspressure in water supply networks. It will make a shorter working time andincrease the probability of pipe explosion and other hidden dangers. It can alsocause splash phenomenon because of the pressure caused by over high valuewhen users in buildings open water facilities.‘The invisible waste of waterresources’ is an extremely serious problem. It can’t be ignored, and need to besolved.The common solution to this phenomenon is to install a pressure reducingorifice or a pressure reducing valve in the pipe which can greatly reduce thesurplus pressure in the pipe. Pressure reducing orifice has the advantages of lowcost and simple structure but it has the problem of unadjustable and lowdecompression efficiency. Pressure reducing valve has adjustable function,while it has the problems of the high cost of maintenance and replacement. Sothis paper put forward a new pressure-relief device which has adjustable fencestructure. This device can change the opening degree to achieve different stress efficiencies, and to make lower water pressure value in the outlet.We will study the decompression efficiency and the decompressionmechanism of this pressure-relief device through three ways. Firstly, wemeasure decompression efficiency of pressure-relief device by model test. Andthen, FLUENT is used to make the numerical simulation for this pressure-reliefdevice in more condition. Finally, we had built a Pressure~flow modelaccording to the theoretical analysis. Then we use methods like decomposition,analogy, differential and integration to set up a mathematical expression relyingon the knowledge such as fluid mechanics and higher mathematics. In a certainvelocity range, the mathematical expression can express the relationshipsamong three variables which are the pressure of inlet, the pressure of outlet andflow velocity.We get the following conclusions through above methods:(1) The pressure-relief device has a complex geometry.When the waterflows through the pressure-relief device, the pressure will be reduced obviously.Its decompression efficiency can meet the use requirement.(2)The decompression efficiency in numerical simulation is0.8%lowerthan the decompression efficiency in model test. The difference is small. Thesame change rules of decompression efficiency are got in model test andnumerical simulation, when opening degree and flow velocity change.(3) When the opening degrees of the pressure-relief device change from0°to30°, the decompression efficiencies of the pressure-relief device increase; the decompression efficiencies of the pressure-relief device decrease with theincrease of flow velocities.(4)A Pressure~Flow model is built in the fourth chapter. The expressionshows that the decompression efficiency of pressure-relief device is a quadraticpolynomial function about water flow in the pipe.(5) It is can be seen that pressure-relief device served as the boundary, thepipe fluid flow process of micelle in the decompression device is divided intothree parts through the numerical simulation of the pressure distribution insurface x=0m. We can get an expression to describe the relationship amongwater flow, pressure in inlet and outlet the pipe flow.(6) We make a nonlinear fitting with the Pressure~Flow model and thedata is used to solve parameters in Pressure~Flow model. Finally, we get=7486210512510.3, which is the relationship betweenpressure difference and velocity.