Fluid flow and heat transfer in a rectangular ribbed channel with a hierarchical design for turbine blade internal cooling

For internal cooling of a turbine blade, various advanced rib turbulators can markedly contribute to the heat transfer enhancement while suffering a great increase in pressure loss. In those designs, ribs with the same configuration are periodically and evenly mounted on the channel wall. In this context, this work proposes a hierarchical design concept to optimize the rib arrangement with the desired reduction in pressure loss. In terms of the rib height, this new design concept is implemented to construct three new rib configurations. Based on an established turbulence model, three-dimensional (3D) numerical simulations are entirely adopted to verify the feasibility of the new configuration in a wide Reynolds number range. The numerical results demonstrate that the optimal configuration with a linearly decreasing rib height can greatly reduce the pressure loss with a slight heat transfer deterioration. The negligible reduction in the heat transfer performance results from the enhanced fluid impingement on the reattachment region because of the lowering effect of the mainstream, although small ribs weaken the fluid impingement. The marked pressure drop reduction comes from the combination of the lowering effect and small ribs which constrains the separation vortex behind ribs. Furthermore, the comparison of the overall thermal performance is carried out considering a wide range of the Reynolds number, pitch ratios, and aspect ratios. The optimal configuration can greatly enhance the overall thermal performance up to 138.3% for the factor (Nu/Nu(0))/(f/f(0)) and up to 32.5% for the factor (Nu/Nu(0))/(f/f(0))(1/3). Eliminating the entrance effect of developing flow, the increment in the overall thermal performance is considerably reduced but still keeps at a high level. Finally, it is significantly highlighted that as a simple but effective improvement, the hierarchical design concept presents great potential in developing high-performance internal cooling of turbine blades.

Automated summary

This study proposes a hierarchical design concept to optimize the arrangement of rib turbulators for internal cooling of turbine blades, aiming to reduce pressure loss while maintaining heat transfer performance. Numerical simulations verify the feasibility of the proposed design and demonstrate that the optimized configuration greatly reduces pressure loss with a slight deterioration in heat transfer. The comparison of overall thermal performance shows significant improvement, indicating the potential of the hierarchical design concept in developing high-performance internal cooling of turbine blades.