自由圆湍射流不稳定性与界面拟序结构研究

发布时间：2018-05-31 10:37

本文选题：射流 + 拟序结构　；参考：《农业机械学报》2016年02期

【摘要】：采用两相流动的大涡模拟对自由圆湍射流的流动不稳定性及界面拟序结构进行了数值模拟。通过计算探讨了射流液体的不稳定性机制。研究了喷嘴入口速度及入口扰动对射流近场区的不稳定性和涡结构特性的影响。研究中,对雷诺数在10 000~80 000内施加不同强度扰动后的射流流场进行了系统的模拟计算。结果表明:射流入口速度及外部扰动对射流的稳定性有重要的作用,随射流速度和扰动强度增加,其未扰液核长度下降,表面波尺度减小,射流近场区产生更为丰富(长度尺度多、涡旋强度范围大)的特征涡旋结构;从射流的时均流场看出,在相同雷诺数不同扰动强度(或相同扰动强度不同雷诺数)下射流时均速度沿中心轴线衰减率基本类似;随雷诺数增加,射流对周围流体的正卷吸作用加强,沿流向的径向扩散更为显著。
[Abstract]:The flow instability of a free circular turbulent jet and the coherent structure of the interface are numerically simulated by using the large eddy simulation of the two-phase flow. The instability mechanism of jet liquid is discussed by calculation. The influence of nozzle inlet velocity and inlet disturbance on the instability and vortex structure in the near field of jet was studied. In the study, the jet flow field with different intensity disturbance in the Reynolds number of 10000m ~ (80) 000 has been simulated and calculated systematically. The results show that the jet inlet velocity and external disturbance play an important role in the stability of the jet. With the increase of the jet velocity and disturbance intensity, the length of the undisturbed fluid core decreases and the surface wave scale decreases. In the near field of the jet, the characteristic vortex structure is more abundant (the length scale is more, the vortex intensity range is large), and it can be seen from the time average flow field of the jet, Under the same Reynolds number and different disturbance intensity (or the same disturbance intensity and different Reynolds number), the attenuation rate of the average velocity along the central axis is basically similar, and with the increase of Reynolds number, the positive entrainment of the jet on the surrounding fluid is strengthened. The radial diffusion along the flow direction is more obvious.
【作者单位】：江苏大学能源与动力工程学院;皇家理工学院力学部;
【基金】：国家自然科学基金项目(51176065) 江苏省研究生科研创新基金项目(CXZZ11!0567) 江苏高校优势学科建设工程项目
【分类号】：O358

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