射流作用下槽边集气罩轴向速度分布规律分析

Analysis of axial velocity distribution law of the slot side gas-collecting hood under jet action

为了降低局部通风系统控制污染物所需能耗,研究了射流作用下槽边集气罩轴向速度分布规律。通过数值模拟分析了无射流条件下排风量对无量纲轴向速度的影响,探讨了射流速度与罩口风速相等条件下集气系统气流流场特性。以数值模拟结果为基础,对比研究了射流角A_(j)及送风口长度L_(s)在不同范围内控制风速的变化规律。结果表明:排风量并不影响轴心速度的变化趋势;送风口沿A_(j)的负方向喷出气流时,汇流场轴向速度衰减变缓,控制风速在A_(j)为-10°时达到最大值,达到罩口风速的0.76倍;最佳L_(s)值为工作台宽度的0.4倍,超过该值时的控制风速不再增加,V_(c)为0.57 V_(e)。

In order to reduce the energy consumption of the local ventilation system for contaminants control,the axial velocity distribution law of the slot side gas-collecting hood under jet action was studied.The influence of exhaust air volume on the dimensionless axial velocity without jet and the flow field characteristics of the gas gathering system under the condition that the jet velocity was equal to the wind speed at the hood were analyzed by numerical simulation.Based on the results of the numerical simulation,the variation laws of wind speed controlled by the jet angle A_(j) and jet slot length L_(s) varying in different ranges were compared.The results show that the exhaust air volume does not affect the variation of axial velocity.The velocity attenuation becomes slow when the air supply ejects airflow in the opposite direction of the A_(j).When A_(j) is -10°,the control wind speed reaches the maximum value,which is 0.76 times of the wind speed at the hood.The optimum value of L_(s) is 0.4 times the width of the worktable,and V_(c)=0.57 V_(e) at this time.When the value of L_(s) exceeds the above value,the control wind speed will not increase.