Effects of detached V-shaped ribs in cooling channels on turbulent flow and temperature distributions, heat transfer and friction factor

肋粗化流固界面是设计高效热交换器部件的一种合适方法。结构表面能够在热交换器的结构材料温度限制内在冷却剂和受热壁之间传递高热流密度。本研究项目的目的是在不同的几何参数和热水力条件下，研究肋诱导湍流结构对方形通道肋的传热和流动阻力的影响。目前的研究表明，附加60°v形肋的应用可以有效地增强传热。肋诱导的二次流运动增加了垂直平均流速，从而增强了对流换热和高湍流混合。然而，在凹肋角附近和附肋的再循环区域出现了换热恶化的流动停滞区。通过从壁上分离肋，可以减少局部传热恶化。肋与壁面的位移引起肋下的间隙流。气流像壁面射流一样离开间隙，并与尾流相互作用。因此，流动停滞区和伴随的局部传热恶化被最小化。假设这两种特性的结合是有利的，即分离式60°v形肋的应用导致热混合增加，固体-流体表面温度均匀，局部和全局传热增强，因此，比附加肋提供更有效的性能。结果将通过复杂的测量活动（LDA，压力传感器，红外热像仪，热电偶）和尺度分辨大涡流模拟获得，并将为湍流，热近壁流动的基础研究做出重大贡献。此外，假设本项目的研究成果可以在传热元件的研究领域进行创新和优化。

Rib-roughening fluid-solid interfaces is an appropriate method for designing thermally effective heat-exchanger components. Structured surfaces enable the transfer of high heat flux rates between a coolant and the heated wall within the structural material temperature limits of heat exchangers. The objective of the present research project is the investigation of effects of rib-induced turbulent flow structures on heat transfer and flow resistance in a square channel rib-roughened by detached 60° V-shaped ribs on one channel wall for varying geometrical parameters and thermal-hydraulic conditions.The state of the art showed that the application of attached 60° V-shaped ribs causes efficient heat transfer enhancement. Rib-induced secondary flow motion increases the vertical mean flow velocity yielding enhanced convective heat transfer and high turbulent mixing. However, flow stagnation zones with deteriorated heat exchange occur in the vicinity of the concave rib-corners and in the recirculation regions of attached ribs. By detaching ribs from the wall, local heat transfer deterioration can be reduced. The displacement of the ribs from the wall induces a gap flow beneath the ribs. The flow exits the gap like a wall-jet flow and interacts with the wake flow. Thus, flow stagnation regions and the accompanied local heat transfer deterioration are minimized. It is assumed that the combination of these both favored attributes, i.e. that the application of detached 60° V-shaped ribs leads to increased thermal mixing, homogeneous solid-fluid surface temperature and enhanced local and global heat transfer and, thus, to a more effective performance than provided by attached ribs. The results will be obtained by a sophisticated measurement campaign (LDA, pressure sensores, IR-Thermography, thermocouples) and scale-resolving Large-Eddy-Simulations and will contribute significantly to the fundamental research of turbulent, thermal near wall flows. Furthermore, it is assumed that the results of the present project can initiate innovation and optimization in the research filed of heat transfer components.