Rib-induced flow structures and heat transfer in the cooling channel of a strut heat shield

As the thrust-to-weight ratios of aero-engine continue to rise, the thermal conditions faced by the strut heat shield, which is a load-bearing protective component positioned between the turbine exit and the afterburner inlet, are becoming progressively more demanding. Aiming at the problem of flow and heat transfer in the middle chord region of the internal channel on strut heat shield, this paper takes the ribbed flat channel with multi-row array film holes as the research object. Through the combination of transient liquid crystal (TLC) experiment and numerical simulation, the flow and heat transfer characteristics of three rib structures (Case 1, Case 2, Case 3) under the condition with a Re range of 30,000–90,000 were systematically studied. The experimental results show that the Nu of three rib structures increases significantly with the increase of Re , and the Case 3 structure can form a larger range of high heat transfer area at lower Re , and there is no obvious heat transfer dead zone behind the rib. At Re = 90,000, the area-averaged Nu of Case 3 exceeds those of Case 1 and Case 2 by approximately 52.98% and 39.75%, respectively. As the Re increases from 30,000 to 90,000, the spanwise average Nu of three rib structures increases by 107.24%, 111.59% and 163.58%, respectively. Case 3 is more sensitive to Re changes and the increase is most significant. Through the analysis of flow resistance results, the friction factor of Case 3 structure is about 1.425 times that of the smooth plate, which is higher than the other two rib structures. Nevertheless, the thermal performance factor ( TPF ) of Case 3 demonstrates most favorable overall performance under all investigated conditions. Furthermore, Case 3 is able to sustain relatively high levels of turbulent kinetic energy and wall shear stress in the downstream rib region, thereby avoiding the unfavorable combination of “high turbulent kinetic energy–low wall shear stress” observed in Case 1 and Case 2. This feature effectively strengthens near-wall flow disturbance and promotes heat transfer enhancement. The results of this study illustrate the influence mechanisms of rib-induced secondary flow and its coupling with film hole effusion on the local heat transfer characteristics within the strut heat shield. These findings provide a valuable reference for the optimal design of internal cooling structures for strut heat shields.