Investigation of the cooling characteristics of a novel parallel-flow double-wall structure under low pressure ratio supply conditions

Double-wall cooling structures are vital for protecting gas turbine hot-section components. However, traditional series-flow double-wall (SFDW) designs suffer from high flow resistance under high external pressure and low coolant-to-mainstream pressure ratios, leading to insufficient film supply and limiting their application in critical regions such as turbine leading edges. To address this, a novel parallel-flow double-wall (PFDW) structure with hollow pin-fins is proposed. By decoupling impingement and film cooling paths, the PFDW design reduces flow losses and enhances backflow resistance while maintaining strong cooling performance. A conjugate heat transfer simulation is conducted to evaluate and compare the PFDW and SFDW structures in terms of film effectiveness, impingement Nusselt number, overall cooling efficiency, flow coefficient, and backflow margin over a range of pressure ratios. Results show that the PFDW structure improves impingement Nusselt number by up to 37.3% and overall cooling efficiency by 20.2%. The discharge coefficients of both cooling paths are significantly higher, and the backflow margin increases by up to 94.92%. These findings highlight the PFDW structure’s effectiveness in ensuring sufficient film supply and pressure resistance under low-pressure conditions, offering a promising solution for turbine cooling applications.