钉盘磨流场数值模拟及齿钉受力分析

Numerical Simulation of Force on Pins in a Pin Pulverizer and Mechanism Analysis

针对钉盘磨内颗粒运动规律的研究和在工作时产生的振动问题及减小阻力的迫切要求,应用计算流体动力学(Computational fluid dynamics,CFD)方法,采用切应力输运(Shear stress transport,SST)湍流模型和滑移网格,在齿钉转速为3000r/min,入口速度为18.26m/s的工况下,对磨机齿钉的受力情况进行预测。在进行数值计算之前,对计算模型和计算网格均进行了算例考核。计算结果表明:钉盘磨的振动和所受阻力矩的情况和单个齿钉的绕流情况密切相关。通过对计算结果的分析,提出了一种估计齿钉受力情况的方法,即:将齿钉和流体的相对运动简化为流体绕固定齿钉的绕流运动,确定来流方向和雷诺数;根据前人研究假设绕流升、阻力均按正弦规律变化,且阻力变化频率为升力的2倍;将升、阻力分解为齿钉在水平方向和垂直方向的力,并求解其随齿钉转动位置的变化规律。运用该方法在相同工况下的计算结果与CFD的计算结果对比发现,新方法可以较好地估计齿钉的受力情况,且比CFD计算更简便。这为钉盘磨的设计提供了一定的参考。

Computational fluid dynamics knowledge is used to overcome the pins＇ vibration and meet the requirement of small. Shear stress transport turbulence model and slide mesh are applied to numerical calculatior The calculation is carried out to predict forces on pins under the following conditions： rotary speed of pins is 3000r/min, inlet velocity is 18.26m/s. The numerical model and mesh are verified before the calculation The result shows that pulverizer＇s vibration and rotating resistance are closely related with the problem of flow around a circular pin. A method is proposed to predict forces on pins based on the numerical result. The method is described as： simplify the relative motion between pin and flow as flow around a restrained pin, decide the direction of the flow and Reynolds number; lift and drag force are assumed sinusoidal and the frequency of lift force is two times than that of drag force; solve the horizontal and vertical component of lift force and drag force, and the changing relation between components and the pin＇s positior Comparison between the solutions of new method and CFD proves that new method can predict pins＇ forces conveniently than CFD. It lays a foundation for the design of pin pulverizer.