一种新型仿生翅片及其对流体流动与传热影响

Influence on Fluid Flow and Heat Transfer of a Bionic Fin in Plate-fin Heat Exchanger

研究板翅换热器翅片结构对流体流动以及传热影响,结合鲨鱼鳃型结构,提出一种鲨鳃型强化传热翅片。该翅片的主要作用在于增大流体流动过程中的湍流效应,改变同层翅片不同流道内流体的流动方向,促进不同流道内流体穿梭流动,降低换热器同层翅片相同截面流体温差,提升换热器的传热效果。通过改变鲨鳃型翅片开口上翘角度α、开口大小s,分别研究12种工况下换热器内部温度场、速度场、压力场以及湍流场的变化特性,得出新型翅片结构下板翅换热器内流体速度、温度、压力以及湍流强度分布。从分析结果中可看出,s=1 mm换热器内流体速度变化最大达到47.38%,温度变化达0.7℃/m,换热器流道内湍流强度达0.816%。α=10°流体湍流强度达到3.162%,温度差值最大达到1℃/m。分析结果表明翅片开口大小s对流体流场的影响要强于上翘角度α,对温度场变化的影响则要弱于翅片上翘角度α,翅片开口角度对换热器内速度与压强影响不大。

The effect of fluid flow and heat transfer caused by fins in plate-fin heat exchanger is investigated, and then a new kind of fins, called shark gill fin, is proposed. The main functions of this kind of fins include enlarging fluid turbulence effect, changing flow direction in the same layer of fins, promoting fluid flow among channels, decreasing fluid temperature difference in the same cross-section and finally promoting heat exchange efficiency. The temperature, velocity, pressure and turbulence field under twelve conditions are analyzed by changing cocking-up structure and opening size in shark gill fin and finally, the distribution of fluid flow, temperature, dynamic pressure and turbulent intensity under steady state conditions are achieved. It can be concluded that when the opening size is 1 mm, the fluid velocity difference can reach by 47.38%, the temperature difference can reach by 0.7 ℃/m, the turbulent intensity difference can reach by 0.816%. When cocking-up structure is 10°, the fluid turbulent intensity can reach by 3.162%, the temperature difference can reach by 1 ℃/m. The results demonstrate that, in view of fluid flow, the effect of opening size is more important than cocking-up degree while, in view of temperature field, the opening size is less important than the cocking-up degree, besides, the cocking-up degree has less effect on fluid velocity and dynamic pressure.