双介质液动力止回阀设计与研究

发布时间：2018-05-08 18:27

本文选题：双介质 + 止回阀　；参考：《太原理工大学》2017年硕士论文

【摘要】：随着我国煤矿开采向深井方向发展,井下排水技术也日趋成熟,止回阀已成为煤矿排水系统中不可或缺的设备,可防止断电等突发原因造成矿井水倒流对水泵及水锤发生附近管路的破坏,保证了作业人员的人身安全。普通止回阀关闭速度较快,水泵等设备会受到因较大压力波动产生的水锤作用而损坏;而关闭速度较慢的微阻缓闭止回阀会因矿井水中的杂质在阻尼装置内堆积而失效。本文分析和研究了微阻缓闭止回阀的工作原理及问题,根据实际使用工况提出了新型止回阀的设计目标。经过多次方案论证优化,最终确定了双介质液动力止回阀的设计方案,最后进行结构设计与优化。当突然断电液体倒流时,该止回阀可缓慢关闭从而避免产生水锤,同时采用双介质避免排水系统中杂质对缓冲装置的堵塞。利用动网格技术对止回阀的关键机构—缓冲装置进行动态仿真。根据阀芯在运动的两个阶段有不同等效孔径的特点,利用离散数据的曲线拟合分别得到这两种等效孔径下动态阻力与速度的关系,为研究缓冲装置性能提供依据。结果表明动态阻力与速度的平方成正比,阻尼孔使阀芯在运动过程中受到很大的阻力作用,缓冲装置具有良好的缓冲效果。利用FLUENT软件对止回阀内流场进行数值模拟,分别对离心泵正常运行时液体正向流经止回阀和突然断电时液体反向流经止回阀两种工况下止回阀的内流场分布进行可视化分析,对止回阀的液动力和阻力特性进行计算,通过内流场及液动力情况可确定阀芯两阶段的开度分界点。仿真结果表明开度小于40%时流场变化较为复杂且液动力较大,可将该开度作为两阶段的分界点,阀芯小于该开度的范围内需缓慢运动,且开度越小流阻系数越大、流量系数越小。对液体作用力下阀芯进行流固耦合数值模拟,得到阀芯应力与应变发生的部位及数值,根据仿真结果对阀芯进行优化,达到了提高阀芯抗形变的目的。仿真表明阀芯最大总变形量出现在阀瓣上,过大的变形量会影响止回阀密封;较大的等效应力出现在阀杆与阀体、阀杆与阀瓣的接触部位,过大的等效应力会使零件压溃损坏;阀瓣结构变为上、下表面为圆弧面不仅提高了阀芯抗形变的能力,而且使内流场更加平稳。设计了一种止回阀模拟试验台,利用齿轮泵、容积泵两种水泵的共同作用模拟出矿井排水系统扬程大、惯性大的效果。该模拟系统可测试离心泵正常运行时液体正向流动与突然断电时液体反向流动两种工况下止回阀的工作性能,并可利用多路阀对这两种工况快速切换。该模拟试验台更加符合矿井排水实际情况,对止回阀性能研究具有很大帮助。利用LMS Test Lab对自由模态下止回阀进行测试得到结构件频率分布情况,为确定止回阀的扰动频率提供范围。
[Abstract]:With the development of coal mining in China towards deep wells, downhole drainage technology is becoming more and more mature. Check valve has become an indispensable equipment in coal mine drainage system. It can prevent the mine water backflow from damaging the water pump and water hammer and ensure the personal safety of the workers. The ordinary check valve is closed faster, the water pump and other equipment will be damaged by the water hammer caused by the larger pressure fluctuation, while the slow stop check valve with slower closing speed will fail because of the accumulation of impurities in the damping device in the mine water. This paper analyzes and studies the working principle and problems of the micro resistance slow closing check valve and puts forward the design goal of the new type check valve according to the actual working conditions. The design scheme of double medium hydrodynamic check valve was determined after several schemes were proved and optimized. Finally, the structure design and optimization were carried out. The check valve can be closed slowly to avoid water hammer when the power is suddenly cut back, and the double medium is used to avoid the blockage of the buffer device by impurities in the drainage system. The dynamic simulation of the key mechanism of the check valve, the buffer device, is carried out by using the dynamic grid technology. According to the characteristic that the spool has different equivalent aperture in the two stages of movement, the relationship between the dynamic resistance and the velocity under the two kinds of equivalent aperture is obtained by using the curve fitting of the discrete data, which provides the basis for the study of the performance of the buffer device. The results show that the dynamic resistance is proportional to the square of the velocity, the damping hole makes the valve core suffer great resistance in the course of movement, and the buffer device has a good buffering effect. The internal flow field of check valve is simulated by FLUENT software, and the flow field distribution of check valve is visualized under the normal operation of centrifugal pump and the reverse flow of liquid flow through check valve during the sudden power failure. The hydraulic and resistance characteristics of the check valve are calculated. The opening and boundary point of the two stages of the valve core can be determined by the internal flow field and the hydrodynamic condition. The simulation results show that when the opening is less than 40, the variation of the flow field is more complicated and the fluid power is larger. The opening can be regarded as the boundary point of the two stages. The valve core needs to move slowly when the opening is smaller than the opening, and the flow resistance coefficient of the smaller the opening is, the greater the flow resistance coefficient is. The flow coefficient is smaller. The fluid-solid coupling numerical simulation of the valve core under liquid force is carried out to obtain the position and value of the stress and strain of the valve core. According to the simulation results, the valve core is optimized to achieve the purpose of improving the deformation resistance of the valve core. The simulation results show that the maximum total deformation of the spool appears on the disc, the excessive deformation will affect the seal of the check valve, the larger equivalent stress appears in the stem and body, the contact position between the stem and the valve disc, and the excessive equivalent stress will make the parts crumble and damage. The disc structure becomes upper and the lower surface is circular surface which not only improves the ability of the spool to resist deformation but also makes the inner flow field more stable. A kind of simulative test bed of check valve is designed. The combined action of gear pump and volumetric pump is used to simulate the effect of large lift and large inertia of mine drainage system. The simulation system can test the performance of the check valve under the two working conditions of the liquid forward flow and the liquid reverse flow during the normal operation of the centrifugal pump and the reverse flow of the liquid during the sudden power failure, and can quickly switch between the two conditions by using the multi-way valve. The simulation test bench is more suitable for mine drainage, and it is helpful to study the performance of check valve. LMS Test Lab is used to test the check valve in free mode to obtain the frequency distribution of the structural parts, which provides a range for determining the disturbance frequency of the check valve.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD442

【参考文献】