1. College of Safety Science and Engineering,Liaoning Technical University,Fuxin　 123000,China; 2. Key Laboratory of Mine Thermodynamic Disasters and Control of Ministry of Education,Fuxin　 123000,China; 3. Safety Engineering Department,Xinjiang Institute of Engineering,Urumqi　 830000,China

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。

Wall jet in heading face has both mean and turbulence characteristics that makes it have replacement and mixing effects on the air flow field. Thus,wind fluctuations play critical roles in the transportation and diffusion of gas and dust,for example,dust suspension entirely depends on that effect. However,the available experimental data on the subject are rather limited due to the limitations of experimental equipment and its complexity. This paper studies the turbulence characteristics of wall jet in heading face. For this purpose,the authors carried out some measurements of instantaneous 3D velocity in experimental model by using a three-dimensional laser doppler anemometer. After that,the authors have studied the distribution and scale of the turbulence intensity that calculated from the experiment data based on the statistical theories of turbulence. The experimental results indicate that there are serious wind fluctuations not only in the jet zone but also in the recirculation zone affected by the return flow and the side walls. The turbulence intensity in three directions are anisotropy but in the same order. Besides,the authors noticed that turbulence intensity increases firstly and then decreases with the distance from the axis of the jet reached the recirculation zone where the turbulence intensity are closer to the magnitudes of the mean air velocity. According to the analysis,shear instability that caused by velocity gradient between the flow layer is an important factor to cause the violent turbulence. At last, the authors suggest that a full attention should be given to the fluctuation term in motion equations when a further study of ventilation efficiency and migration law of gas and dust in heading face is made by any means.

LIU Jian,LI Xuebing,DENG Lijun,et al. Turbulence characteristics of wall jet in heading face using a laser doppler anemometer[J]. Jour- nal of China Coal Society,2017,42(8):1926-1931.