涡轮叶片内冷表面V肋-凹陷复合流动控制强化传热优化设计

Heat Transfer Optimization Design of Flow Control on V Rib- Dimple Hybrid Surface in Turbine Blade Internal Cooling

关键词:  涡轮叶片  冷却  传热  数值模拟  多目标优化  流动控制

Key words:  Turbine blade  Cooling  Heat transfer  Numerical simulation  Multi-objective optimization  Flow control

摘要:

通过基于Kriging代理模型的多目标优化方法针对Re=50500条件下矩形通道内单面排布的V肋-凹陷流动控制结构进行优化设计。通过稳态实验及瞬态热色液晶实验充分地验证了数值方法。获得了努塞尔数比最高的结构（肋高径比e/D_h=0.1，凹陷深径比δ/d=0.21，肋-肋间距比P/e=10.8，肋-凹陷间距比L/e=9.9）和综合传热因子（TPF）最高的结构（e/D_h=0.08，δ/d=0.19，P/e=13.5，L/e=12.3）。结合数值模拟解析优化结构的强化传热机理，较高肋（e/D_h=0.1）诱发的强附着流和较深凹陷（δ/d=0.21）的卷吸共同作用导致掠过肋的流体强烈地下洗冲击肋后平板，较大的间距比（L/e=9.9）为流体提供了宽广的附着区域，附着后的流体进入凹陷打破回流区，从凹陷后缘分离冲出后主流剪切并遭遇下排肋前收缩，强掺混增强了湍流热输运。通过改变复合结构中凹陷的位置调控附着后流体的流动以实现强化传热。

Abstract:

The parameter optimization is carried out for the V rib-dimple flow control structures on one wall of the rectangular channel at Re=50500 by the multi-objective optimization method based on the Kriging surrogate model. The numerical method is fully verified by steady-state and transient TLC experiments. The structure with the highest Nusselt number ratio （rib height-to-diameter ratio e/D_h=0.1， dimple depth-to-diameter ratio δ/d=0.21， rib pinch-to-height ratio P/e=10.8， rib-dimple spacing-to-height ratio L/e=9.9） and the structure with the highest thermal performance factor （TPF） （e/D_h=0.08， δ/d=0.19， P/e=13.5， L/e=12.3） are obtained. The heat transfer enhancement mechanism of the optimal structure is analyzed by numerical simulations. The interaction of the strongly attached flow induced by the higher rib （e/D_h=0.1） and the suction of the deep dimple （δ/d=0.21） results in the intense downwash of the fluid passing the rib against the flat wall downstream of the rib. The large spacing ratio （L/e=9.9） provides a large attachment area for the fluid. The attached fluid enters the dimple， breaks the recirculation zone， and detaches from the trailing edge of the dimple， then the fluid shears with the mainstream and contracts before the next-row ribs. The intensive fluid mixing increases the turbulence heat transfer. By changing the position of the dimple， the flow of the attached fluid can be controlled to enhance heat transfer.