【作者】 刘欣；

【导师】 杨锋苓；

【作者基本信息】 山东大学 ， 化工过程机械， 2020， 硕士

【摘要】 搅拌反应器在生物、制药和石油等行业有着广泛的应用。搅拌设备的振动影响零部件的工作性能,增加混合功耗,降低搅拌效率。如果发生共振现象,缩短设备工作寿命,严重时还会发生安全事故。因此,针对课题组前期开发的柔性Rushton搅拌桨进行振动特性研究。采用数值模拟和实验测试相结合的方法研究桨轴系统的振动特性,并进一步分析转速和搅拌介质对于振动特性的影响。采用CFD数值模拟的方法对搅拌系统的流场特性进行分析,并采用流固耦合的方法对桨轴系统进行受力特性分析。结果表明,搅拌桨叶正面尾端出现压力最大值,桨叶周围出现速度最大值。桨轴系统的最大应力位于柔性桨叶和刚性桨叶的连接处,最大变形位于柔性桨叶尾端,连接处是最容易导致桨轴系统失效的部位,安全系数随着转速或者搅拌介质粘度的增加而减小。利用数值模拟的方法对桨轴系统进行振动特性分析,主要求解无预应力和有预应力时的各阶固有频率和振型。结果表明,预应力会使各阶固有频率有所下降,下降比例均在3%以下;预应力使变形桨叶的数量减少,桨叶变形量均有不同程度的增大。为了避免桨轴系统产生较大的响应,应当避开206 Hz和255 Hz。计算求得搅拌轴的临界转速为1452.6 r·min-1。通过实验测试的方法研究桨轴系统的振动特性,使用BK振动测试仪和DH微型测试仪分别测量静止和转动状态下的振动特性。结果表明,静止状态的阻尼比为5.11%,转动状态的阻尼比为7.07%。与实验相比,无预应力模态分析和预应力模态分析仿真的前12阶固有频率均有所增加,增加比例均在6%以下。采用预应力模态分析仿真的方法,研究不同的转速或搅拌介质对振动特性的影响。结果表明,前12阶固有频率随着转速的增加均有不同程度的下降。随着搅拌介质粘度的增加,前12阶固有频率均有不同程度的增加。高转速对于各阶固有频率的影响大于低转速。转速和搅拌介质粘度对于低阶固有频率的影响在整体上要大于高阶。更多还原

【Abstract】 Stirred reactors were widely used in industries such as biology,pharmaceuticals and petroleum.The vibration of the mixing equipment affected the working performance of the parts,increased the mixing power consumption,and reduced the mixing efficiency.If resonance occured,the working life of the equipment was shortened,and safety accidents might occur in serious cases.Therefore,the vibration characteristics of the flexible-blade Rushton impeller developed by the research group in the early stage were studied.A combination of numerical simulation and experimental measurement was used to study the vibration characteristics of the propeller shaft system,and further analyze the influence of the rotational speed and the stirring medium on the vibration characteristics.The CFD numerical simulation method was used to analyze the flow field characteristics of the mixing system,and the fluid-structure interaction method was used to analyze the force characteristics of the propeller shaft system.The results shown that the maximum pressure appeared at the tail end of the stirring blade’s front,and the maximum speed appeared around the blade.The maximum stress of the propeller shaft system was located at the connection between the flexible blade and the rigid blade,and the maximum deformation was located at the tail end of the flexible blade.The connection was the most likely part of the propeller shaft system to fail.The safety factor decreased as the rotational speed or viscosity of the stirring medium increased.Use numerical simulation method to analyze the vibration characteristics of the propeller shaft system,and mainly solve the natural frequency and vibration mode of each order without prestress and with prestress.The results shown that the prestress reduced the natural frequency of each order,but the reduction ratios were all below 3%.The number of deformed blades decreased,and the amount of blade deformation increased to varying degrees under prestress.In order to avoid a large response from the propeller shaft system,206 Hz and 255 Hz should be avoided.The critical rotational speed of the stirring shaft was calculated to be 1452.6 r·min-1.The vibration characteristics of the propeller shaft system was studied by experimental measurement,and use BK vibration tester and DH mini-tester to measure the vibration characteristics of static and rotational state respectively.The results shown that the damping ratio is 5.11%in the static state,and the damping ratio was 7.07%in the rotational state.Compared with the experiment,the 1st～12th order natural frequencies of the unprestressed modal analysis and the prestressed modal analysis all increased,and the increase ratios were all below 6%.The method of prestressed modal analysis was used to study the influence of different rotational speeds or stirring media on vibration characteristics.The 1st～12th order natural frequencies all decreased with the increase of the rotational speed.And with the viscosity of the stirring medium increasing,The 1st～12th order natural frequencies all increased.The influence of high rotational speed on the natural frequency of each order was greater than that of low rotational speed,and the influence of rotational speed or the viscosity of the stirring medium on the low-order natural frequencies was greater than that of the high-order as a whole.更多还原