【作者】 张志明；

【导师】 沈明启；

【作者基本信息】 哈尔滨工程大学 ， 核能科学与工程， 2011， 硕士

【摘要】 船用核动力装置与民用核动力装置相比,由于其特殊的工作环境和性能要求,所以在结构上有所不同。为了保证船用核动力装置在特殊情况下工作的稳定性,其一回路设计有备用回路。备用回路和主回路之间通过止回阀进行连接,它们之间可以互相切换工作。在切换的过程中,不但要求阀门能够稳定可靠的工作,而且还要求它不能完全关死。否则不工作的回路会因为水温过低而影响反应堆的稳定性。这就对止回阀的性能提出了更多的要求。本文所要研究的止回阀就是针对上述问题设计制造的。它有别于传统意义上的止回阀,由于其对冲原理可以大大减小阀的水击作用。本文的研究是在前人研究的基础上,针对对冲式止回阀原理样机在实验中出现低流量关不上关不严的问题,对主止回阀的结构提出了改进。应用AutoCAD和Pro/E对止回阀改进结构的流道进行建模,并且用GAMBIT划分完网格,最后用CFD软件FLUENT对阀的关闭过程进行数值模拟。计算出阀门在关闭过程中压力变化云图、速度变化云图、阀头阀座的受力变化曲线以及速度变化曲线,通过这些参数来判断阀门的工作状态,找出止回阀存在的问题的根源并加以解决。最后通过实验验证理论分析的结果,对比理论值与实际值之间的差距并分析原因。通过动态模拟得到了阀头阀座的受力曲线、速度曲线以及流量变化曲线。计算的结果表明,在各种工况下阀门都能够自动关闭,阀座的受力和运动速度都明显大于阀头的。阀头阀座的受力和运动速度都是随着时间的增大而增大。逆流压差的大小直接影响回流量的大小和阀门的关闭速度以及阀头阀座的受力。压差越大,阀头阀座的受力和运动速度越大,回流量越大。更多还原

【Abstract】 Compared with the Civil Nuclear Power Plant (CNPP), the Marine Nuclear Power Plant (MNPP) is very different from that in structure due to its special work environment and performance requirement. It is necessary to equip with the spare loop in MNPP to ensure its stability under special circumstances. The spare loop and primary loop, which are connected by the check valve, can be switched to work. When it was switched to another circuit, the valve, on one hand, should work stably, on the other hand, should not be closed tightly or else the other non-working loop will influence the stability of the nuclear reactors because of the lower temperature. Therefore, more requirements are needed for the performance of the check valve.In the paper, the valve is designed to solve the problems mentioned above. It is distinguished with the traditional valve for the hedging principle adopted can deduce the water hammer pressure to the valve. On the basis of the previous research, the structure of the primary valve is to be improved aiming to deal with the inner leakage problem of the low-flowing prototype under the reverse check valve principle. By adoption of AutoCAD and Pro/E, the flow channel of the improved check valve is modeled; mesh is generated by GAMBIT, and the check valve closure process is numerically simulated by CFD software. Thus, the pressure changes contours of the closure process, velocity changes contours, the force changes curve and the velocity changes curve can be obtained. Based on these parameters, the work statement of the valve can be determined as well as the existing problem can be found and solved. To testify the theoretically analyzed results, experiments must be resorted and the differences between the theoretical results and the practical ones should be analyzed.By dynamic simulation, the time dependent graphs of the forces on valve head and seat, velocity and flow rate variation can be obtained. The results show that the new-type check valve can close automatically under different operating conditions. The force and velocity on the valve seat are significantly greater than those on the valve head. As the time increases, the force and velocity are increasing. The pressure difference of counter flow will influence the reflux flow, the velocity of closing and the force on valve head and seat directly. The larger pressure difference is, the greater the valve head force and the motion speed will be, the greater the valve seat force and the motion speed are as well as back to more flux.更多还原