【摘要】 采用SST湍流模型对带旋流的三维环形后台阶的流场进行了数值分析,比较了不同孔阶比和来流旋流数对环形后台阶流场的影响.结果表明:在合适的边界条件和计算网格下,SST湍流模型对后台阶流动回流区长度的预测能力最佳;当来流旋流数为1.0时,钝体下游的中心回流区长度可以不受钝体孔阶比的影响,从而保证在多种工况下稳定的火焰;随着来流旋流数的增加,中心回流区长度接近正比例增加,来流预旋改变了钝体下游的流动结构,使轴向速度减小,速度峰值移向燃烧室的外侧壁面.通过对钝体孔阶比和旋流数进行联合优化,可得到合理的中心燃烧位置.更多还原

【Abstract】 Numerical simulation was carried out to the 3D pre-swirled flow over an annular backward-facing step of a bluff-body burner using SST turbulence model,during which the influence of step-diameter ratio and inlet swirling number on the flow field analyzed.Results show that under reasonable boundary and grid conditions,the best prediction of recirculation length can be obtained with SST turbulence model.When the inlet pre-swirling number is 1.0,the recirculation length in the downstream of bluff-body will be independent of step-diameter ratio,which helps to stabilize the flame under various operation conditions.With the rise of inlet swirling number,length of central recirculation zone shall be enlarged correspondingly in linear proportion,while the downstream flow field changed,axial flow rate reduced,and the velocity peak moved toward outer wall of the burner.The flame can be reasonably positioned near center line via optimal selection of swirling number and step-diameter ratio.更多还原