The Failure Mechanism Analysis Of The Regulation Valve In A Hirohax-Unit And Improved Design Of The Pipe Line Based On Simulations

Based on the overall analysis of the failure phenomena of the regulation valve LCV-2203 in a Hirohax-Unit, the primary mechanism to interpret the failure is revealed as cavitations. By comparing various techniques of preventing cavitations and considering the situations of the regulation valve, a new design scheme is proposed to optimize the pressure fall in the pipeline. The k-εturbulence model and Simplec arithmetic are employed to simulate and compare the turbulence flow characteristics fore-and-aft the optimization of the pressure fall in channels by using the CFD software Fluent. The calculated results indicate that the turbulence cavitations can be well restrained by introducing a proper set of labyrinth orifices in the pipeline, which shares 30% of the total pressure fall in the channel of the valve originally, so that the service life of the valve can be prolonged and also the economic benefits are increased.Furthermore, the set of labyrinth orifices according to the initial ideas is designed based on the finite element analysis by using ANSYS. Firstly the boundary pressure of the flow field in the labyrinth channel of the set of orifices is calculated by using Fluent, which is transferred as the surface loads applied on the inside walls of the cylinder and orifices in the FE model built by ANSYS. Then, the deformations and stresses are calculated and the strength is estimated for the structure of the cylinder and orifices by using 20-nodes 3D-isoparametric elements, which are very suitable for the structure with complex curved boundary, in ANSYS. The optimization of the geometric parameters (e.g. the thickness of the wall and plates, the cuts and the space between orifices, etc.) is further conducted based on the original scheme, so that a both economic and safe design scheme is finally obtained. Besides, a reasonable welding order of the orifices in the cylinder is determined.In the simulation, a perfect connection of the pressure loads is realized between the different software and models for fluid and structure. This approach can be used as a reference for the design of various complex fluid channels.