Heat/mass transfer augmentation in a leading-edge channel with extended ribs

Gas turbine blade leading-edge cooling is critical due to a high thermal load in the stagnation region. It requires a significant portion of total cooling air supplied to the turbine blade. In order to meet the durability requirement, various cooling schemes are applied. One of the most commonly found in the leading-edge cooling passage is a rib-turbulator design. In this study, a novel rib-turbulator design is investigated for flow and heat transfer characteristics using numerical and experimental methods. The test section was designed to simulate a realistic internal passage, as a triangular channel with a rounded leading-edge. The rib turbulators are installed in a staggered manner. Numerical analyses were performed using a commercial CFD tool, ANSYS CFX. Naphthalene sublimation method was adopted to measure local convective heat/mass transfer distributions. The main geometrical parameter of interest was the extension length of the rib-turbulators (l/e = 0.0, 1.0, 1.5) in the leading-edge region. Based on the parametric study, the optimized case was found, and its heat transfer performance was compared to the baseline (conventional) case. The Reynolds number varied from 20,000 to 40,000. The optimized case showed a 12.7% better heat transfer performance in the leading-edge region than the baseline case at the Reynolds number 30,000 case.