Aiming at the leakage problem on the top of gate valve, the finite element method is used to analyze the gate valves seal face and body, as well as the distributing laws of the stress, deformation and seal pressure are obtained. The shutter is simplified as the circular plate simply supported on the whole circle, and the gate valve is optimized according to the relevant formula to meet sealing requirement. The results show that: the combination of the numerical simulation and theoretical calculation, not only the more accurate theoretical basis for the optimization of the large diameter gate valve can be provided, but also the time of the development and design can be shorten greatly.

In order to promote the localization of critical valve in ultra-supercritical thermal power generating unit, a two-stage superheated electrical steam trap was designed and developed. Its structure and operation principle was introduced. Three-dimensional numerical simulation of the internal turbulent fluid field was performed by using Fluent of computational fluid dynamics software. The results show that the superposed design of associated reaction with multiaperture equalizer and guide sleeve was adopted in the two-stage superheated steam trap. The internal flow field become more uniform, local maximum velocity reached 37.2m/s. The brush erosion of valve seat is reduced and the service life is increased. Success rate of the first sample's trial-manufacture is greatly improved by using CFD simulation experiment in the process of design. Development cycle is shortened and the cost is reduced, which can provide a reference for two-stage superheated steam trap design.

In view of the transient dynamic analysis in opening swing check valve, the motion model of valve clack is built, two-dimensional dynamic numerical simulation of the internal unsteady flow is performed by using dynamic mesh and UDF in opening two kinds of swing check valve at the same working condition, the visualized results are obtained. The results show that internal flow field of the modified model become more stable, the noise, impact and the local energy loss are decreased, the service life is improved obviously; an important reference for swing check valve design and analysis of dynamic characteristics are provided by the research results.

In order to promote the technical progress of pressure reducing valve in nature gas transport system, a high pressure pilot operated axial-flow pressure reducing valve was designed and developed. The three-dimensional modeling of the natural gas pressure reducing valve internal flow passage was found by using Solidworks software. Import the flow channel model into meshing in CFD software based on the internal flow channel geometry and flow characteristics. The ideal gas compressible fluid model of natural gas and improved RNG k-Epsilon model were used to solve the pressure and velocity distribution as well as other flow related parameters of the natural gas pilot operated pressure reducing valve. The flow fields of the pressure reducing valve with different valve plug shape were analyzed. Changes of valve plug shape were made to improve the performance of the valve.

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