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为了表达混凝土多相介质在搅拌过程与其搅拌叶片间的动力学关系,实现混凝土搅拌叶片结构形态的快速设计,提出基于多相流理论的混凝土搅拌叶片快速设计方法。即利用欧拉-欧拉流体动力学方法表达在叶片动边界条件下,混凝土多相介质(石子、泥浆及水等)的流场分布,再通过数值统计处理方法定量化地评价搅拌叶片的搅拌性能,利用响应面函数构造不同叶片动边界条件下的搅拌性能近似模型,以此快速地获得搅拌叶片的优化形态。此基于多相流理论的混凝土搅拌叶片快速设计方法,降低了设计成本,缩短了设计周期,有效地解决了动边界条件下多相流体模型的大自由度动态设计问题,实现搅拌叶片结构的快速设计。 相似文献
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影响混凝土拌合料质量参数较多,混凝土流动特性对生产工艺流程和产品质量等有着重要影响.为提高混凝土的拌合质量,基于流体动力学原理,通过搅拌器试验观察构建数值模型,提出混凝土搅拌过程的流体特性,引入混凝土拌合中的沸腾概念,对混凝土多相流脉动现象和基本特征进行数值模拟分析.在一定条件下沸腾多相流体系统参数将在时域上出现脉动,包含高频和低频成分.脉动高频成分由搅拌运动动力学参数产生,而低频成分则是由混凝土的级配参数产生.搅拌器的工作速度、拌合料密度等对脉动特征有实质性影响. 相似文献
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从改善混凝土搅拌运输车搅拌筒加工条件入手,提出了揽拌筒筒体与封头连接结构型式的改进设计.进而运用Pro/E Wildfire工程软件对改进设计后的搅拌筒进行了结构有限元分析,为搅拌筒的定型提供了理论参考依据。实际工程结果表明,改进设计后的搅拌筒的结构显著地改善了加工条件.明显地提高了加工效率和产品质量。 相似文献
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为研究双卧轴振动搅拌机搅拌筒内流场振动搅拌过程中固液混合流体瞬态流动情况,基于计算流体力学(CFD)提供的计算方法,结合动网格技术、欧拉多相流模型、Realizable k-ε湍流模型及离散相模型,采用C语言编写用户自定义程序(UDF),并将其动态链接到CFD中,在非稳态条件下数值模拟双卧轴振动搅拌机搅拌质量受振动轴转速、固相颗粒体积分数的影响规律,并在此基础上,进行了振动搅拌试验研究。结果表明:当搅拌轴转速为35 r/min、混合料颗粒体积分数为20%、颗粒直径分别为10 mm、20 mm和30 mm时,振动轴转速分别为960 r/min、1 460 r/min和1 800 r/min时其搅拌质量最佳;数值分析结果与试验结论基本一致,说明了数值计算结果的准确性和计算方法的可行性。 相似文献
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在综合分析传统混料机的基础上,对所设计的新型斜轴式高效混料机关键技术进行参数分析。根据斜轴式混料机新型的逆向搅拌原理即搅拌筒体和搅拌轴逆向旋转,利用AUTOCAD画出二维原理图。采用DEM离散元分析方法,使用Solid Works为三维建模软件,将模型导入EDEM中,运用Hertz Mindlin(no lips)无滑动接触模型,模拟仿真混料机筒体倾斜角度、搅拌轴位置以及搅拌叶片长度变化对混合效果的影响,重点介绍简化三维模型的导入、定义仿真参数及后处理图表的分析技术。此方法分析为同类混料机的设计改进提供了方法,具有较高的实用价值。 相似文献
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刀具槽型结构对切削过程影响的仿真研究 总被引:1,自引:1,他引:0
建立了切削过程的仿真模型,分析了改变刀具断屑槽型参数凸台高度和断屑槽宽深比对切削过程的影响。仿真结果对刀具断屑槽型的设计或选用具有参考价值。 相似文献
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应用商用 CFD软件提供的动网格技术,对标准MIRJ模型汽车会车过程的瞬态空气动力特性进行了数值模拟,研究了套车过程中的车辆瞬态空气动力特性,结果表明:对汽车进行瞬态空气动力学数值模拟是可行的,会车过程中两车气动力系数有显著变化,其变化幅度呈类似于正弦函数图像形式的变化趋势,会车时的空气动力作用,对汽车操作稳定性有重大影响. 相似文献
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Physical parameters are very important for vehicle dynamic modeling and analysis. However, most of physical parameter identification methods are assuming some physical parameters of vehicle are known, and the other unknown parameters can be identified. In order to identify physical parameters of vehicle in the case that all physical parameters are unknown, a methodology based on the State Variable Method(SVM) for physical parameter identification of two-axis on-road vehicle is presented. The modal parameters of the vehicle are identified by the SVM, furthermore, the physical parameters of the vehicle are estimated by least squares method. In numerical simulations, physical parameters of Ford Granada are chosen as parameters of vehicle model, and half-sine bump function is chosen to simulate tire stimulated by impulse excitation. The first numerical simulation shows that the present method can identify all of the physical parameters and the largest absolute value of percentage error of the identified physical parameter is 0.205%;and the effect of the errors of additional mass, structural parameter and measurement noise are discussed in the following simulations, the results shows that when signal contains 30 dB noise, the largest absolute value of percentage error of the identification is 3.78%. These simulations verify that the presented method is effective and accurate for physical parameter identification of two-axis on-road vehicles. The proposed methodology can identify all physical parameters of 7-DOF vehicle model by using free-decay responses of vehicle without need to assume some physical parameters are known. 相似文献
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《Measurement》2016
The effect of the drum brake temperature reduction on the clamping force of the parking brake system has not been well addressed despite the fact that it may result in vehicle roll away. In view to this, a parking brake model that takes into account the temperature reduction of the drum brake has to be developed and more importantly, it must comply with the applicable standards or regulations such as Federal Motor Vehicle Safety Standard (FMVSS) 135. This paper develops a one dimensional (1D) model of leading-trailing drum-type parking brake model. This brake model is then verified with experiments carried out on a test bench that has been verified with the hand brake system in the vehicle. The results from the experiments show a good correlation with the predicted results from the brake model. It is also found that the existing parking brake design meets the standard requirements. Another finding is that the brake torque slightly increases as the drum temperature increases. With the verified brake model, parametric studies can be carried out as one of the tools during the design process. From the studies, it is found that rollaway will not happen even with the maximum vehicle weight and friction coefficient at drum/lining interface above 0.2. 相似文献
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Most references on hydropneumatic suspension analysis regard it as harden Duffing spring and take the white noise as the system input, which is quite different from real physical model. It will introdu... 相似文献
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螺旋升角对混凝土搅拌运输车搅拌筒内部流动影响的数值模拟 总被引:1,自引:0,他引:1
通过对三种不同螺旋升角的搅拌筒内部流场的数值模拟,分析了搅拌筒的内部流动情况,讨论了螺旋升角对搅拌筒性能的具体影响,为螺旋升角的合理选取、搅拌叶片设计理论的完善和后续研究工作提供了重要的理论依据. 相似文献
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设计了一种汽车轮内叶轮式磁流变液制动器,根据磁流变液在强磁场下的流变特性,推导出该制动器的制动力矩计算方法,并在Matlab/Simulink环境下建立仿真模型,分析了制动器结构参数对制动力矩的影响。所设计的汽车磁流变液制动器能够满足一般小型汽车的制动力矩需求。 相似文献