掘进工作面附壁射流紊动特性的LDA实验

发布时间：2018-03-31 20:34

本文选题：掘进工作面　切入点：紊动特性　出处：《煤炭学报》2017年08期

【摘要】：掘进工作面附壁射流具有置换和掺混双重作用,体现为流场的时均和紊动特性。射流的紊动在瓦斯粉尘的迁移扩散中起着关键性作用,如工作面粉尘的悬浮运动完全靠风流的紊动得以维持。由于紊动本身的复杂性以及实验设备的限制,以往对独头巷附壁射流的研究一般停留在时均量上,对紊动量的认识还不够深入。为此,采用三维激光多普勒测速仪,在独头巷射流通风实验模型内,对三维脉动风速进行了测量。根据紊流统计理论,分析得到了风流的各向紊动强度,并对紊动强度的分布规律和量级进行了研究。结果表明:受限条件下,由于回流存在,射流的紊动在射流区和回流区都很剧烈,3个方向的紊动强度具有量级相同和各向异性的特点。在射流剪切层内,紊动强度从射流轴线到射流边界呈先增后减趋势;在射流剪切层以外的回流区,紊动整体变化不明显,始终维持着与平均风速大小相当的强度。流场内较大的速度梯度导致流层之间剪切失稳是形成剧烈紊动的重要原因。由于紊动具有与平均风速相近的强度,在研究独头巷风流排污效率、瓦斯粉尘运移规律等问题时,无论理论分析还是数值计算,都应对运动方程中的速度脉动项给予充分重视。
[Abstract]:The wall jet in tunneling face has the dual functions of displacement and mixing, which is embodied in the time-averaged and turbulent characteristics of the flow field. The turbulence of the jet plays a key role in the migration and diffusion of gas dust. If the suspended movement of dust in working face is completely sustained by the turbulence of air flow, due to the complexity of turbulence itself and the limitation of experimental equipment, the previous researches on the wall jet of single head roadway generally stayed on the time average. For this reason, the three-dimensional laser Doppler velocimeter is used to measure the three-dimensional fluctuating wind velocity in the experimental model of jet ventilation in a single-headed roadway, according to the statistical theory of turbulent flow. The turbulence intensity in different directions of wind flow is obtained, and the distribution law and order of magnitude of turbulence intensity are studied. The results show that: under restricted conditions, due to the existence of reflux, In the jet shear layer, the turbulence intensity increases first and then decreases from the jet axis to the jet boundary. In the circumfluence zone outside the jet shear layer, the overall turbulence change is not obvious. The shear instability between the flow layers caused by the large velocity gradient in the flow field is an important reason for the violent turbulence. The turbulence has the intensity similar to the average wind speed. Both theoretical analysis and numerical calculation should pay enough attention to the velocity pulsation term in the motion equation when studying the efficiency of draught discharge and gas dust migration in single-headed roadway.
【作者单位】：辽宁工程技术大学安全科学与工程学院;矿山热动力灾害与防治教育部重点实验室;新疆工程学院安全工程系;
【基金】：国家自然科学基金资助项目(51574142)
【分类号】：TD721

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