Investigations on heat transfer in turbulated cutback surface with Chevron-shaped rib configurations for trailing-edge

The current research proposes a unique turbulated cutback structure for trailing-edge cooling, which places chevron-shaped ribs on the cutback surface to improve heat transfer. An experimental system is established, and the reliability of the numerical method is verified via pressure-sensitive paint (PSP) and transient thermochromic liquid–crystal (TLC) experiments. The adiabatic film effectiveness (η), heat transfer coefficient, and flow physics of the cutback surface with various angles of chevron-shaped ribs are obtained via numerical simulations and compared with those of the traditional smooth case to further analyse and understand the film cooling characteristics of the turbulated cutback structure. Three chevron-shaped rib angles of 30°, 45°, and 60° for three blowing ratios (M) are investigated. The effect of chevron-shaped ribs on η is not notable because the rib height is relatively small. The low η with the “M-shape” is manifested downstream of the cutback surface. In the downstream region of the cutback surface, η becomes weaker with increasing angle, but the values are still above 0.9. The chevron-shaped ribs significantly enhance the heat transfer on the cutback surface, and the area-averaged heat transfer coefficient is 26.3–41.2 % greater than that in the smooth case. The 45-deg case produces a higher heat transfer intensity than the other two chevron-shaped rib cases at the studied M. In the region far downstream, the heat transfer intensity of the 30-deg case is higher than that of the other two cases, whereas it is lower downstream of the slot exit, in which the difference decreases as M increases. At M = 1.0, the area-averaged heat transfer intensity of the cases with large angles of 45 deg and 60 deg reaches its peak. The net heat-flux reduction (NHFR) values of the ribbed structure are consistently greater than those of the smooth case, with an improvement of 4.1–8.8 % at low M and a sharp increase to 26.5 % when M reaches 2.0, confirming enhanced comprehensive cooling performance. Additionally, aerodynamic analysis revealed that, compared with smooth ribs, chevron-shaped ribs increase the total pressure loss coefficient by only approximately 2.2 % and the thermal loss coefficient by approximately 6.3 %, indicating minimal adverse effects on aerodynamic performance.