单侧有限宽度开缝竖通道内的旋转热流体特性

Characteristics of rotating thermal fluid in a vertical shaft with a confined single corner gap

为了掌握竖直通道内的旋转火焰特性及其与通道壁面开口条件的关系,在9 m高的竖通道内通过实验确定了可形成旋转火焰的侧开缝宽度范围,并对通道4 m高度以上的侧开缝宽度限制时的旋转热流场进行了数值模拟。研究发现,限制上部侧开缝宽度后会使通道下部的气体流速和火焰附近的旋转速度加大,从而使旋转力对流场的作用较浮力增大,并使流场旋转中心偏移;与上部开缝宽度未受限时相比,开缝受限使其中性面的高度降低,整个中性面的倾角减少至几乎为零,而且在开缝的靠近前端壁面一侧处,流进通道的气体流速由侧开缝未受限时的随着开口宽度的增加而降低变为随着开缝宽度的增加而增加。

With the purpose to increase the understanding of the relation between fire whirls and the corner gap of the vertical shaft , experiments for the fire whirl were carried out on a vertical shaft at a height of 9 m and the width of the corner gap of the fire whirl formation was verified .Thermal fields were numerically simulated when the width of the corner gap over 4 m was confined .The study shows that the airflow rate at the lower part of the shaft and the rotation speed near the flame are a little higher after the width of the upper corner gap is confined .The effect of the whirling force on the thermal field is more than buoyancy , and the deflection of the center of rotation is made .Com-pared to when the width of the upper corner gap is not confined , the height of the neutral plane is lower and the an-gle of the neutral plane decreases to almost zero when the corner gap is confined .In addition, at the wall of the cor-ner gap near the front of the shaft , the flow velocity increases as the width of the corner gap increases , instead of decreasing with the increase of the width of the corner gap when the upper corner gap is not confined .