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在传统大波动过渡过程计算中,调压室底部连接管的影响往往是作为阻抗孔来考虑,在连接管较长的情况下,采用阻抗孔处理时而忽略了连接管的水体弹性,因而容易造成较大误差。通过建立考虑了连接管及不考虑连接管时的调压室节点数学模型,采用Gardel公式来处理调压室的阻抗系数,将调压室的阻抗系数变为负荷实际情况的动态阻抗系数,并结合具体工程实例来分析连接管的长度及管径的变化对调压室涌浪、蜗壳进口压力以及机组转速所产生的影响。研究结果表明,对于连接管较长的情况,应考虑到连接管的作用,为了能充分反射水锤,连接管的面积不宜过小。 相似文献
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Residual stresses in ferromagnetic material affect the direction and structure of domains and generate magnetic field abnormality on the surface.In the formation of stress induced magnetic field,the influence of geomagnetic field is unclear.Residual stress specimen was produced by tight matching of a round ring and a peg.The magnetic fields of contrast specimens,which were produced in geomagnetic field or in shielding geomagnetic field,were ingspected with 8mm lift-off.The results show that mean amplitude of magnetic field of the specimen produced in geomagnetic field is 0.85% larger than that of specimen produced in shielding geomagnetic field.So the formation of stress induced magnetic field abnormality above the surface of inspected ferromagnetic material geomagnetic field gives little contribution. 相似文献
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提出以电弧作为可控的“超声发射源”的工作原理,开发了具有一定带宽的激励电源用以激发电弧超声,通过传输线耦合方式与常规弧焊电源进行联机试验。在焊接过程中发现了激发电弧超声的若干谐振频段,记录了电弧超声的频率、幅度和相移。该原理表明,电弧不仅可作为“产热机构”,同时也可作为“超声发射机构”,开拓了电弧在焊接过程自动控制、质量检测等方面应用的新途径。 相似文献
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