井壁片螺栓连接的装配式沉井

研发了一种井壁片螺栓连接的装配式沉井,该沉井由上、下部沉井井壁片构成,井壁片的上下、左右边缘均设有与相邻井片相连的凹槽或凸起,形成一道卡槽。利用卡槽进行井壁片的定位组装,并在卡槽中敷设止水橡胶条,达到止水效果,通过预留的手孔或螺栓孔,利用拧紧螺栓将各井壁片连接。井壁片螺栓连接的装配式沉井施工效率高,社会、经济效益好,具有较好的推广应用价值。     

动量式气体流量计内部流场特性与测量性能研究

采用数值模拟与实验验证相结合的方法,得到了动量式气体流量计内部的流场,分析了流量变化时受力元件阻力系数的变化规律,研究了受力元件的形状、安装误差对测量性能的影响。研究结果表明,动量式流量计的阻力系数在量程范围内有较大变化,必须对阻力系数随雷诺数的关系式予以拟合;长方形受力元件阻力系数的拟合公式计算误差最小,拟合结果与实验数据的最大误差为0.32%,应优先选用;安装误差引起的阻力系数误差不大于0.32%,对测量精度影响较小,动量式流量计适合在线安装。     

Numerical study of flow fluctuation attenuation performance of a surge tank

The surge tank plays an important role in ensuring the stability of a water flow standard device. To study the influence of the structure and the working conditions on the regulator performance of a surge tank, a three-dimensional model, including a surge tank, the pipeline and the water tank is built, and the VOF model in the Fluent software is used to simulate the two-phase pulsatile flow in the surge tank. The inlet flow pulsation is defined by the User Defined Functions （UDF）, and the outlet flow is set to be a free jet. By calculating the flow fluctuation coefficient of the variation uader different flow conditions, the influences of the pulse frequency, the initial water level height and the baffle plate structure on the flow stability are analyzed. It is shown that the surge tank has a good attenuation effect on high-frequency pulsations, there is an optimal initial water level to suppress the fluctuations, the round holes of the baffle should ensure a certain circulation area with the bore diameter small enough to have the necessary damping effect.     

IT245旋耕刀正反转功耗有限元数值分析

反转旋耕转向与传统正转旋耕刀转向相反,具有埋茬效果好、碎土能力强、耕土平整性好的特点。但由于反转旋耕比正转旋耕功耗大、油耗大等问题,致使用户的接触程度不高,所以目前国内普遍采用正转旋耕。针对国标普通旋耕刀IT245单刀作业功耗问题,对旋耕刀IT245进行正反转功耗对比。根据土壤力学物理特性,建立具有弹塑性行为的Drucker-Prager强度准则的土壤本构模型。结合农艺要求,在含水率为20%的旱地进行旋耕工作,利用有限元分析软件进行正反转过程数值仿真。结果表明:IT245旋耕刀反转比正转功耗高出17.5%,验证了本构模型功耗仿真的可行性,为下一步进行研究设计专用反转旋耕刀的优化分析奠定基础。     

浅谈科学管理与急倾斜煤矿的生存和发展

市场如战场 ,优胜劣汰 ,适者生存 ,根据新集三矿的发展实践 ,从四个方面分析了科学管理与急倾斜煤矿的生存和发展的关系。