A Trial Manufacture of valves, which work safety in an extreme flow condition

为了使阀门在极端流动条件下安全可靠地工作，系统地观察了蝶阀、门槽和空心射流阀周围的流态，精确地测量了其空蚀损伤。在我们的研究中，我们把蝶阀工具化，因为蝶阀价格便宜，结构相当简单，并且可以平稳地控制流量。利用压力敏感膜和水听器对蝶形阀模型周围的流场进行了观测，并测量了空化压力脉冲。主要研究结果如下：1.利用最大帧频为40，500帧/秒的高速摄像机对蝶阀周围流态的观察结果表明，下游管道表面的冲蚀与孔口射流与回流区之间的高剪切区产生的奇异纵向涡空化密切相关。旋涡空化在回流区发展为严重的冲蚀空化，并与多个旋涡空化相结合.当凸块设置在蝶阀的阀座侧表面上时，上述空化变弱，这是因为孔口射流变弱而不受干扰。利用压力敏感膜测量了空泡脉冲压力，利用激光测速仪测量了空泡噪声.在更换阀垫圈非常方便的偏心蝶阀的情况下，在流向的设置上有两种类型，即凸部设置在阀杆的上游或下游。结果表明，两种类型的设置之间的流量没有差异。

In order to make high reliability valves, which work safety in extreme flow conditions, we systematically observed the flow pattern and precisely measure the cavitation damage arisen around the butterfly-valve, the gate-slot and the hollow-jet-valve. In our study, we tool up the butterfly valve, because the butterfly valves are inexpensive, quite simple in construction, and can control the flow rate smoothly. We observed the flow pattern around a model of the butterfly-valve and measure the cavitation-induced-pressure-pulses by means of a pressure sensitive film and a hydrophone. The obtained results are summarized as follows :1. As a result of the observation of the flow pattern around the butterfly valves by means of a highspeed video camera, whose maximum framing rate is 40, 500 frames per second, the erosion on the surface of the downstream-pipe is closely related to the singular longitudinal vortex cavitation associated the high shear region between the orifice jet and the recirculating region. The vortex cavitation develops into the severely erosive cavitation in the recirculating region with combining the several vortex cavitations.2. The above-mentioned cavitation is weak as the projection is set on the orifice-side-surface of the butterfly valve, because the orifice jet becomes weak to be disturbed. We also make clear the cavitation-impulsive-pressures by means of the pressure sensitive film, and the cavitation noises by means of a hydrophone.3. In the case of the eccentric butterfly valve, in which it is very convenient to change the valve washer, there are two types on the setting to the flow direction, namely the convex part sets on the upstream or the downstream to the valve stem. It is shown that there is no difference on the flow rates between the two types of the setting.