过渡流下后向台阶流动与瞬态传热特性研究

Subjects: Dynamic and Electric Engineering >> Engineering Thermophysics submitted time 2018-02-01 Cooperative journals: 《工程热物理学报》

仲敏波1,2 谢纬安2 袁银男1,2 喜冠南1,2

Abstract： 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 (Num) 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 Num. 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

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