顶部侧开缝的倾斜通道热流场及开口中性面研究

Researches on the thermal flow field and the neutral planes at two open ends of inclined channel with corner gap at upper wall

为了掌握通道在上壁面不同宽度的开缝条件下,不同倾斜角度的通道内热流场特性及两端开口处中性面高度的变化规律,对一200 cm长的通道内一靠近低端开口一侧火源产生的热流场进行了实验与基于Vreman亚格子模型的大涡模拟研究.通过实验值与数值模拟结果的对比,验证了构建的数学模型对于上壁面有侧开缝的倾斜通道内热流场模拟的有效性;确定了通道上壁面的开缝对于通道内热流场的温度分层特性、通道两端开口处U速度以及中性面高度随着通道倾角变化的规律影响不大;对于一定的通道倾斜角度,随着通道上壁面侧开缝宽度增大,火源两端温度分布的对称性增强,通道上壁面附近的温度降低,通道内的高温区域向下壁面的偏移幅度减弱,通道两端开口处靠近上壁面附近的空气流速逐渐降低,两端开口处中性面高度升高;上壁面有开缝的通道两端开口处中性面的高度曲线随着通道倾斜角度的增大有一个交叉,交叉发生在通道倾斜角度小于5°时.

In order to understand the characteristics of the thermal flow field and the change law of height of neutral planes at inclined channel with different gaps at the upper wall under different angles, experiments and large eddy simulation were conducted. The experiments were conducted on a thermal flow field generated by the fire near to low end of an inclined 200cm long channel, corresponding simulations were executed utilizing a Vreman sub-grid scale model. The comparison between experimental values and numerical simulation results validated effectiveness of thermal flow field simulation of inclined channel with comer gaps at upper wall. The gap of channel had little influ- ence on the therroal stratification, U-velocity at two ends and the change of height of neutral plane with inclination of channel. As the gap width increased at fixed angle of channel, the symmetry of temperature distribution on fire was strengthened, temperature near upper wall dropped, the shifting range of high temperature area to was reduced, velocity of air flow near upper wall had a tendency to decrease and height of neutral planes ends increased. The findings indicate the intersection happened at an angle of inclination of channel less height curves of neutral plane at two open ends when the channel had a gap at the upper wall. two sides of bottom side at two open than 5° for height curves of neutral plane at two open ends when the channel had a gap at the upper wall.