论文部分内容阅读
为分析单狭缝、双狭缝和四狭缝射流冲击柱状凸形表面的流动换热特性,应用Realizable k-模型对其展开数值研究。通过与实验数据对比验证了数学模型的适用性,比较探讨了单、多狭缝冲击射流的流场分布、边界层分离现象和冲击换热特点。结果表明:单、多狭缝射流冲击柱状凸形表面,气体分别在流动阻力和相邻狭缝射流逆向相遇阻力形成的逆压梯度作用下,发生边界层分离;随流动发展,多狭缝射流在相邻射流逆向相遇作用下,Nu迅速下降至最低值,随后在逆流作用下有所回升;每狭缝具有相同雷诺数Re条件下,当狭缝数目增加时,Re的增加对提高平均努塞尔数Num的效果相对较小,当无量纲曲率半径(D/B)增大时,Num对Re的变化更加敏感,增大Re将有效地增加表面Num;狭缝射流总流量一定时,狭缝数目越多,Num越小,局部努塞尔数Nu分布越均匀。
In order to analyze the heat transfer characteristics of the cylindrical, convex, and single-slit, double-slit, and four-slit jets, a Realizable k- The applicability of the mathematical model is verified by comparison with the experimental data. The flow field distribution, the boundary layer separation phenomenon and the impact heat transfer characteristics of single and multi-slit jet are discussed. The results show that the single and multi-slit jet impinges on the cylindrical convex surface and the gas separates at the boundary layer due to the pressure gradient formed by the resistance of flow and the resistance of the adjacent slit jet. With the development of flow, Under the reverse confluence of adjacent jets, Nu rapidly decreased to the lowest value and then rose backwards under the reverse flow. With the same Reynolds number Re at each slit, as the number of slits increases, the increase of Re increases the average The effect of Num is relatively small. When the dimensionless radius of curvature (D / B) increases, Num is more sensitive to the change of Re. Increasing Re will effectively increase the surface Num. When the total flow of the slit jet is constant, The more the number of slits, the smaller the Num, the more uniform the Nusselt number distribution.