对夹式止回阀动态特性分析及结构优化

发布时间：2018-04-14 11:25

本文选题：对夹式止回阀 + 汽蚀现象　；参考：《兰州理工大学》2017年硕士论文

【摘要】：对夹式止回阀作为自力式控制类阀门,能够有效防止管路内介质倒流,泵及电机反转等情况的发生。在国家大力发展智慧城市之际,其在楼宇自动化领域、水冷系统中起重要作用,然而国内对于对夹式止回阀的理论研究缺失现象严重,依靠企业单独试验辅以经验总结已严重滞后于产品的更新发展步伐。本文以浙江省科技厅重大科技专项为依托,对应用于系统流程的高可靠性的对夹式止回阀进行理论分析研究。本文详细介绍对夹式止回阀的物理结构,描述对夹式止回阀的工作原理,重点分析流量与阀瓣开角之间的关系,并理论推导出相应计算公式;对湍流状态下流经对夹式止回阀的流体进行三维静态模拟,确定不同开度角下对夹式止回阀的流阻系数及速度压力分布情况;为表征特性因素的瞬态变化规律,建立开启过程二维动态模型,编译UDF程序驱动运动部件及相关区域的瞬态变化,对阀门开启过程进行监控,分析不同时刻压力速度变化情况,并对阀内流场出现的旋涡现象进行初步探讨。借鉴静音止回阀阀内流线设计,对对夹式止回阀阀内流道进行动态模拟,选择出最佳流线以改善阀体附近小涡的能量耗散,减弱止回阀开启过程伴随的汽蚀现象;阀门开启过程中能量的耗散主要由两方面构成:其一,存在于阀瓣背水区域,表象为强烈的旋涡现象;其二,开启过程阀前出现的水锤现象。为提升能量利用率进行结构的优化设计,并对优化后的结构进行动态数值分析,对比优化前后特征曲线,验证优化结构对缩小负压区及防止水锤的有效性。通过上述对止回阀的优化分析,对比实验验证结果表明:优化阀内流道后对夹式止回阀最佳开度角增长26°;结构优化后,止回阀在压差开启过程中,压差平缓减小,防水锤效果明显。阀内流体旋度减小,旋涡数量及强度减弱,开启过程中伴随的振动与噪声现象得到很好改善,阀门的流阻系数减小25%以上,提高阀门的流通量,为旋启式止回阀系列产品的优化设计提供参考。
[Abstract]:As an independent control valve, clamped check valve can effectively prevent medium backflow, pump and motor inversion in the pipeline.When the country develops the intelligent city vigorously, it plays an important role in the field of building automation, water cooling system. However, the theoretical research on the clamped check valve is seriously missing in our country.Depending on enterprises' individual test and experience summary, it has lagged behind the pace of product renewal and development.Based on the important science and technology project of Zhejiang Science and Technology Department, this paper makes a theoretical analysis and research on the high reliability check valve applied to the system flow.This paper introduces the physical structure of the clamped check valve, describes the working principle of the clamped check valve, analyzes the relationship between the flow rate and the valve disc opening angle, and deduces the corresponding calculation formula theoretically.The flow resistance coefficient and velocity and pressure distribution of clamped check valve at different opening angles were determined by three-dimensional static simulation of flow through the clamped check valve in turbulent state, in order to characterize the transient change law of characteristic factors, the flow resistance coefficient and velocity pressure distribution of clamped check valve were determined under different opening angles.The two-dimensional dynamic model of the opening process is established, and the transient changes of the moving parts and related regions driven by the UDF program are compiled. The valve opening process is monitored and the pressure and velocity changes at different times are analyzed.The vortex phenomenon in the valve flow field is discussed.Referring to the design of the inner flow line of the mute check valve, the dynamic simulation of the inner passage of the clamped check valve is carried out, and the optimum flow line is selected to improve the energy dissipation of the vortex near the valve body and to weaken the cavitation phenomenon accompanying with the opening process of the check valve.The energy dissipation during valve opening mainly consists of two aspects: first, it exists in the back water area of the valve disc, which appears as a strong vortex phenomenon; second, the water hammer phenomenon appears in front of the valve during the opening process.In order to improve the efficiency of energy utilization, the optimization design of the structure is carried out, and the dynamic numerical analysis of the optimized structure is carried out. Compared with the characteristic curves before and after the optimization, the effectiveness of the optimized structure in reducing the negative pressure area and preventing the water hammer is verified.Through the above optimization analysis of check valve, the result of contrast experiment shows that the optimum opening angle of clamped check valve increases by 26 掳after optimizing the flow channel of valve, and the pressure difference of check valve decreases gently during the process of differential pressure opening after structure optimization.The effect of waterproof hammer is obvious.The flow curl in the valve decreases, the number and intensity of the vortex weaken, the vibration and noise phenomenon accompanying in the opening process are improved very well, the flow resistance coefficient of the valve is reduced by more than 25%, and the flow flux of the valve is increased.It provides a reference for the optimization design of the series of rotary check valves.
【学位授予单位】：兰州理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH134

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