激波加载单元体球阵列时的流场和非稳态阻力研究

发布时间：2018-01-17 20:33

本文关键词：激波加载单元体球阵列时的流场和非稳态阻力研究　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：激波与固体颗粒群的相互作用问题是超音速气固两相流研究领域的一个重要课题,其研究成果在航空航天、医疗卫生、安全防控等领域都有着重要的应用。所以对于激波与颗粒群相互作用机理的进一步研究有助于超音速气固两相流理论的发展和完善以及工业生产相关技术的改进。本文基于ICEM、Fluent等软件组成的CFD计算平台,以及Origin、Tecplot等后处理软件,数值模拟了激波加载下三种周期性边界单元体模型球阵的周围流场和非稳态阻力。通过对压力云图和非稳态阻力系数变化曲线的同步对比,揭示了单元体模型球阵非稳态阻力的产生机理和变化规律。本文研究的主要内容和结论如下:1、对单元体内不同球的阻力系数曲线进行对比分析,发现单元体内阻力系数变化规律具有稳定性、相似性,证明了将阻力系数模型扩展到颗粒群中的可行性。2、对于目标单元体中的单个球,其阻力系数变化规律受到入射激波、前排球衍射激波、同排球和后排球反射激波以及激波-激波相互作用后形成的各种波形结构的影响。所以要比单球、双球、四球等模型受力复杂得多。阻力系数变化规律为先急剧增到到峰值,在单调下降到一个谷值,随后继续增到到第二个峰值,再波动下降出现一个最小值波谷,最后在0附近震荡并逐渐趋于稳定。3、在入射激波与单元体相互作用阶段(大概对应无量纲时间t’=1~3),入射激波阵面与单元体内球的相对位置决定了阻力系数的变化趋势,即当激波阵面处于球前驻点到赤道位置时阻力系数上升,当激波阵面处于赤道到后主点位置时阻力系数下降。4、对于单元体A,阻力系数峰值随着空隙比(无量纲间距)的增大而减小,并且空隙比越大,在入射激波与单元体相互作用结束之后阻力系数越容易趋于稳定。5、对于A、B、C三种单元体来说,阻力系数都随着马赫数的增大而减小,且曳马赫数越大,入射激波与单元体相互作用结束后阻力系数越容易趋于稳定。6、在模型球阵中的前后排球(垂直与激波来流方向)对周围流场和激波结构的影响要比同排相邻球大。7、在所有工况条件下,单元体阻力系数变化曲线的第二波峰都高于第一波峰,造成这现象的主要原因是因为激波的二次反射。
[Abstract]:The interaction between shock wave and solid particle group is an important subject in the field of supersonic gas-solid two-phase flow. Therefore, the further study of the interaction mechanism between shock wave and particle group is helpful to the development and perfection of supersonic gas-solid two-phase flow theory and the improvement of related technology in industrial production. This article is based on ICEM. Fluent and other software composed of CFD computing platform, and original Tecplot and other post-processing software. The flow field and unsteady resistance around the spherical array of three periodic boundary element models under shock loading are numerically simulated. The mechanism and variation of unsteady resistance of the spherical array in the unit model are revealed. The main contents and conclusions of this paper are as follows: 1. The resistance coefficient curves of different spheres in the unit are compared and analyzed. It is found that the variation law of resistance coefficient is stable and similar. It is proved that it is feasible to extend the resistance coefficient model to particle group for a single sphere in the target unit. The law of change of drag coefficient is influenced by incident shock wave, diffraction shock wave of front volleyball, all kinds of wave structure formed by interaction of reflected shock wave and shock wave with volleyball and rear volleyball, so it is more than single ball and double ball. The variation law of resistance coefficient is that the resistance coefficient increases to the peak value at first, decreases to a valley value monotonously, then continues to increase to the second peak value, and then the fluctuation decreases to a minimum trough. Finally, it oscillates near 0 and tends to be stable gradually. 3, at the stage of interaction between incident shock wave and unit body (approximately corresponding to dimensionless time t ~ 1 ~ (-1) ~ (3)). The relative position of the incident shock front and the sphere inside the element determines the variation trend of the drag coefficient, that is, the resistance coefficient increases when the shock front is at the stop point in front of the ball to the equator position. When the shock front is at the position from the equator to the rear main point, the drag coefficient decreases by .4.The peak value of the drag coefficient decreases with the increase of the void ratio (dimensionless spacing), and the larger the void ratio is. When the interaction between incident shock wave and the element body is finished, the resistance coefficient tends to be stable. 5. For the three kinds of unit bodies, the resistance coefficient decreases with the increase of Mach number. The larger the number of drag Mach is, the easier the resistance coefficient tends to be stable when the interaction between incident shock wave and element body is finished. The influence of the front and back volleyball (vertical and shock wave direction) on the surrounding flow field and shock wave structure in the model spherical array is larger than that in the same row adjacent sphere. The second peak of the resistance coefficient curve is higher than the first wave peak, which is mainly caused by the secondary reflection of shock wave.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O354.5

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