客舱内自然对流运动对流场影响的实验研究

Experimental Research on the Influence of Natural Convection on the Flow Field in the Cabin Mockup

空间狭小且乘客密集的客舱内流场是自然对流与强制对流相互作用的结果.针对自然对流对舱内流场的影响,以Boeing737-200的7排模拟舱为研究对象,采用二维粒子图像测速法(PIV)测量舱内流场,对比等温与非等温流场定性分析自然对流的加入对舱内热环境的影响:宏观上,可加强流场对称性和流速分布均匀;微观上,加强射流卷吸和削弱贴壁效应.在此基础上进一步设置多种设计范围内的合理实验工况,以阿基米德数(Ar)和雷诺数(Re)量化分析自然对流运动对射流和整体流场的影响:自然对流作用的增强使射流衰减趋势更加缓慢,射流中心衰减系数Cw与Ar存在正比的线性关系;Re>3,800和Ar<6时,可在过道中线一侧形成完整涡旋流动.

The flow field is actually the result of natural convection and forced convection interaction inside the cabin with narrow interior space and passengers seated intensively. To study the effect of the natural convection on the air- flow field inside occupied cabins, a full-scale 7-rows cabin mockup of Boeing737-200 has been researched with a two-dimensional particle image velocimetry （2D-PIV） system. The flow fields under isothermal and cooling conditions were compared and it was found out that the natural convection enhanced the flow field symmetry and uniformity macroscopically, and strengthened the air jet entrainment and weakened the air jet adherent effect microscopically. Then, a variety of conditions were set within a reasonable range of design parameters based on the above qualitative analysis for further measurements, so as to quantify the effects of natural convection on the air jet and the overall flow field with Archimedes number （At） and Reynolds number （Re）. Two important conclusions can be obtained. One is that the air jet centerline velocity decay rate becomes slower with the enhancement of the natural convection, which means the air-jet velocity decay coefficient Cw is in proportion to At; the other is that a fully rotary airflow can be maintained on one side of the cabin, divided by the centerline of the aisle, when Re〉 3 800 and At〈 6.