摘要
为了研究过渡流下后向台阶的流动与瞬态传热特性,建立了二维不可压缩后向台阶流动的数值传热模型,采用非定常数值方式模拟了后向台阶的内部流场,比较了台阶下游底面瞬时努塞尔数Nu和时均努塞尔数Nu_m的分布,分析了台阶下游通道内温度分布规律。结果表明:过渡流下台阶底面Nu数沿着流动方向出现多个峰值,Nu数始终围绕Nu_m数发生波动。Re数为700时,主回流区未出现二次回流,Nu数在主回流区下游才发生波动;Re数为1200时,主回流区出现二次回流,Nu数在主回流区就发生了波动。台阶下游通道内温度沿法向呈阶梯式变化,Re数越大,近底面处的温度变化梯度也越大。
In order to study the flow field and the instantaneous heat transfer characteristics for backward-facing step in transition flow,a two-dimensional incompressible numerical model of backward-facing step flow was established.The internal flow field was studied with the unsteady numerical method.The instantaneous Nusselt number(Nu) and the time-averaged Nusselt number(Nu_m) distributed on the bottom wall were compared.The temperature distribution of the channel was analyzed.The results show that Nu appears multiple peaks on the bottom wall along the flow direction in transition flow.The distribution of Nu always fluctuates around the Nu_m.When the Reynolds number is 700,Nu fluctuates only in the downstream of the primary recirculation region because there is no secondary recirculation zone in the primary recirculation region.When the Reynolds number is 1200,Nu fluctuation occurs in the primary recirculation region because secondary reflux appears in the primary recirculation region.The temperature changes in the form of step in the normal direction for the channel downstream of the step.The larger the Reynolds number is,the greater the temperature gradient is.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2015年第1期136-141,共6页
Journal of Engineering Thermophysics
基金
国家自然科学基金资助项目(No.51476080)
关键词
过渡流
传热特性
数值模拟
后向台阶
transition flow
heat transfer characteristics
numerical simulation
backward-facing step
