Numerical Simulations and Pressure Measurements of the Flow of an Oily Control Valve for Decreasing its Operating Noise.

随着操作压力的增加，气蚀引起的阀门噪声经常成为严重的问题。本研究通过对牛犊在闭合和开启过程中的内部流动的研究，有助于对牛犊的优化设计和空化噪声的降低。首先，在雷诺数约为10^3的情况下，对不同结构的锥阀进行了噪声测试，并在假设非空化的情况下，用有限差分法对其进行了数值模拟。此外，我们还在阀室的两个位置进行了压力测量、流动显示和噪声测试。通过对测量结果和计算结果的比较，得到了流型和噪声测量之间的良好对应。证实了噪声主要由气蚀产生，并强烈依赖于阀芯和套筒的阀门配置。大的阀腔是治疗…的有效方法第二级节流器通过抑制周期性涡旋的产生，有效地降低了压力脉动。另一方面，在膨胀阀的情况下，分别对层流和湍流(kappa-epsilon湍流模型)进行了模拟。对于层流，锥体下游沿燃烧室轴线有较强的涡街，压力脉动也增大；而对于Kappa-epsilon湍流模型，从锥体分离出来的射流在燃烧室壁面上重新附着，在锥体后方形成回流区，压力脉动减小。这些结果与可视化结果吻合得很好。其次，针对滑阀，对不同的阀门结构进行了数值模拟。计算了不同阀门启闭比下的静态特性和启闭过程中的动态特性，如流型、轴向力、射流角度等。对于静态特性，流体力发生变化，与流过阀门和相关回流区的流动方向有很大的对应。针对动特性、非定常流态、合闸和合闸瞬变过程中的力波动进行了数值模拟。验证了阀肩形成的涡流与高频流体力的脉动分量之间的对应关系。在实验中，既使用了实际阀门，也使用了实际阀门的一半尺寸的阀门模型。使用称重传感器测量了不同阀门开启/关闭比下的轴向力。测量结果与模拟结果吻合较好。此外，用半尺寸模型显示的流型与模拟结果在定量上符合得很好。假定为层流、轴对称流动，t小于

The valve noise due to cavitation has frequently been serious problems with the increase of an operating pressure. This study contributes to the optimistic design of velve and to the decrease of cavitation noise by studying the internal flow of the calve in the transient process of closing and opening. First, at Reynolds number of about 10 ^3, for poppet valves with different configurations, we have carried out noise tests and numerically simulated oil-flows under an assumption of noncavitating conditions by a finite difference method. In addition, we have performed the measurements of pressure at two locations in a valve chamber, the flow visualization and noise tests. By comparison of the measured and computed results, good correspondences between the flow pattern and noise measurements were obtained. It is confirmed that the noise is mainly generated from cavitation and strongly depends on the valve configuration of the poppets and the sleeves. A large valve chamber is effective to … More suppress cavitation due to the formation of a stationary large circulating flow, and the second stage restrictors is effective to reduce the pressure fluctuation by suppressing the generation of periodic vortiodic vortices. On the other hand in the case of expansion valve, simulation were made for both laminar and turbulent (kappa-epsilon turbulence model) flows. For laminar flow, strong vortex street was observed to shed along the axis of chamber downstream the poppet and pressure fluctuation also increases, while for turbulent flow by kappa-epsilon turbulence model, the jet flow separated from the poppet gets reattached over chamber walls, resulting in the formation of recirculation region just behind the poppet and the decrease of pressure fluctuation. These results agree well with visualization. Second, for spool valve, nomerical simulations were conducted for various valve configuration. The static characteristics at various valve open/close ratios and dynamic characteristics in the transient process of opening and closing operation, such as flow patterns, axial forces and angles of jet were computed. For static characteristics, fluid forces change, greatly corresponding with the flow direction through the valve and the associated recirculation region. For dynamic characteristics, unsteady flow patterns, force fluctuations in the transient process of closing and opening operations were numerically simulated. Correspondence between the vortices formed from valve shoulder and the fluctuating component of fluid forces with high frequency was certified. In experiments, both actual valves and valve-models with half size of actual one were employed. Axial forces at various valve open/cose ratios were measured using a load cell. The measured results agree well with those of simulations. In addition, flow-patterns visualized with the half size model were found to agree quantiatively well with those of simulations. With the assumption of laminar, axial symmetric flow, t Less