流固耦合的多层搅拌反应器振动特性研究

Analysis on a multiple-impeller considering the fluid-structure interaction and its vibration characteristics

针对某型号搅拌反应器搅拌主轴因振动断裂的问题,基于流固耦合理论,采用CFD和FEM相结合的单向耦合稳态的数值模拟以及经验公式计算方法。在考虑流场作用的条件下分析多种方法得出搅拌器的临界转速结果。分析主轴断裂的原因及影响搅拌器的固有频率的流体因素,并对主轴结构进行改进。得出结论:主轴驱动电机转速大于主轴的最低设计转速是主轴产生振动断裂的主要原因;搅拌介质的流体力和阻尼作用对搅拌器的固有频率均有影响;可以将主轴适当加粗以提高其临界转速,从而远离共振范围并有效解决振动问题;采用流固耦合的方法能够考虑搅拌器转动、流体载荷和搅拌桨叶的影响。其计算结果比经验公式更接近实际情况。

Aiming at analysing the damage mechanism of the stirring spindle of a certain type of mixing reactor due to vibration fault, based on the theory of fluid solid coupling, a numerical simulation, by using the combined method of CFD and FEM, on the one-way coupled stationary vibration was carried out and an empirical formula calculation was also conducted for comparison. Considering the effect of the flow field, the critical speed of the mixer was analyzed. The causes of the spindle fracture and the effect of the fluid factors on the natural frequency of the mixer was analyzed. On this basis, the structure of the spindle was improved. It is concluded that the motor speed, driving the spindle, greater than the minimum design spindle speed is the main reason of the vibration generating the main shaft fracture. The effect of the fluid force and damping on the natural frequency of the mixer is obvious. The enlargement of diameter can increase the critical speed, shift away from the resonance range and solve the vibration problem effectively. The method of analysing the fluid solid coupling can be used to investigate the influences of the rotation of the agitator, the load of the fluid and the mixing blades. The reults are more close to the actual situation than those by the empirical formula.