Numerical Simulation of Flow Field Characteristics and the Energy Dissipation Rate of Porous orifice Plate

The water delivery of pipelines in mountainous areas is faced with problems such as large elevation difference and high water head.In order to meet the downstream water use requirements,energy dissipation and pressure reduction measures need to be set in the downstream area. At present,the most economical and practical measure is orifice energy dissipation. The orifice plate has simple structure,low manufacturing cost,high energy dissipation rate and can well meet the working requirements. Thus it is more and more widely used in throttling and pressure reduction. There are many studies on single orifice and multi-stage orifice plates,but there are too few studies on porous orifice plates. In order to explore the changes of flow field characteristics and energy dissipation rate after setting porous orifice in pressurized pipeline,global structured grid and global unstructured grid are adopted for comparative analysis in this paper. In addition,pressure-based type and transient is adopted in the solver setup. So as to truly reflect the flow characteristics,gravity is considered. Besides,the Realizable k-εmodel is used to simulate the flow field and energy dissipation rate of five different types of orifice plates and the wall function method are used to deal with the boundary conditions. The results show that:The results of using global unstructured grid and the Realizable k-ε model are in good agreement with the experimental results,and the maximum relative error is 6.81%. The research on the flow field characteristics behind different porous orifice plates shows that when the water flows through the orifice plate,the flow movement state changes under the influence of its narrow flow. After passing through the orifice plate,the pressure decreases rapidly,and a vortex area is formed in the back,and the length of the reflux area formed by different types of orifice plates is different. Research findings on energy dissipation rate of different porous orifice plates shows that the energy dissipation rate of porous orifice is closely related to the opening rate and Re. The smaller the opening rate is,the better the energy dissipation effect is,The highest energy dissipation rate is 97.1%;The dissipation rate increases rapidly with the increase of the Re and then slowly increases,The maximum increase is 7%. Through dimensional analysis and curve fitting,the empirical formula of energy dissipation rate of porous plate is obtained,The relative error between the calculated value and the measured value is controlled within ± 6%.