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研究了燃烧风洞内不同纵向风速、不同火源功率条件下,隧道近火源区顶部温度沿纵向分布情况。结果表明,纵向风对不同尺寸火源条件下的顶部温度的影响呈不同特征。对较小尺寸火源,隧道顶部温升随风速增加而减小至稳定值;而对较大尺寸火源,顶部温升随风速增加先增加后减小。对于矩形火源,当纵向风较小(0.5~1.5m/s)时,长边平行于纵向风时顶部最高温升大于长边垂直于纵向风的情况;而当纵向风较大(≥2 m/s)时,两种油盘放置方式的顶部最高温升一致。纵向风作用下,顶部最高温升位置向下游呈现“两次移动”特征,即随着纵向风速增加该位置先向下游移动,当风速达到某一值时,隧道拱顶的加热机制由对流和辐射共同主控转变为辐射单独主控,最高温升位置突变回到上游后再次逐渐向下游移动。
The longitudinal distribution of the temperature near the top of the tunnel near the fire source is studied under different longitudinal wind speeds and different sources of ignition power in the wind tunnel. The results show that the longitudinal wind has different characteristics on the top temperature under different size of fire source. For smaller size fire sources, the temperature rise at the top of the tunnel decreases with the increase of wind speed to a steady value. For larger size fire sources, the temperature rise at the top first increases and then decreases with the increase of wind speed. For the rectangular fire source, when the longitudinal wind is small (0.5 ~ 1.5m / s), the maximum temperature rise of the top when the long side is parallel to the longitudinal wind is greater than that of the long side perpendicular to the longitudinal wind. When the longitudinal wind is larger (≥2 m / s), the top of the two oil pan placement of the highest temperature rise consistent. When the wind speed reaches a certain value, the heating mechanism of the dome of the tunnel changes from the “double moving” feature to the downstream under the action of longitudinal wind, that is, as the longitudinal wind speed increases, Convection and radiation co-master into a separate radiation master, the highest temperature rise mutation back to the upstream and then gradually moved downstream.