An inverse thickness matching method for preliminary design of double-wall turbine blades under thermal and mechanical loads

The application of advanced double-wall cooling technology in turbine blades faces significant strength challenges due to high temperature gradients caused by enhanced cooling. This study introduces a cylinder double-wall model to simplify the double-wall turbine blade and analyze the mechanical behavior. A total of 294 cases combining 7 wall thickness ratios, 6 temperature gradients, and 7 centrifugal loads are investigated to analyze their effects on stress field. Then, a novel inverse matching design method for wall thickness of double-wall structure is developed. The key idea is that compressive stress caused by thermal load and tensile centrifugal stress from mechanical load can counteract each other under coupled conditions. By adjusting the wall thickness, the stress level can be regulated to match the thermal and mechanical loads, thereby minimizing the stress on the critical outer wall. Applied to a double-wall turbine blade, this method not only inversely gives the best thickness design but also provides guidance for adjusting wall thickness to improve strength performance. The maximum reduction in area-averaged stress is 2.43% and outer wall stress decreases by up to 11.67%. The proposed method provides a valuable approach for the conceptual and preliminary design of double-wall turbine blades.