COOLED MOVING BLADE FOR GAS TURBINES

摘要

With a gas turbine systems, there is an increasing trend to use a high temperature combustion gas to enhance the operating efficiency of the gas turbine. This, however, is accompanied by the generation of cracks at an increased frequency in a base portion of the blade where thermal stress of large magnitude is likely to occur. An object of the invention is to provide a cooled moving blade for a gas turbine which has a blade profile capable of more effectively reducing thermal stress in a blade base portion, and thus, prevent cracks from occurring. A moving blade (1) is fixedly secured to a platform (2). On the other hand, a cooling air passage (3) is formed in a serpentine pattern inside of the blade for cooling with cooling air. The moving blade (1) has a base portion of a profile formed by an elliptically curved surface (11) and a rectilinear surface portion (12), wherein the rectilinear surface portion (12) is provided at a hub portion of the blade where thermal stress is large. In the conventional moving blade, the base portion is formed as an elliptic fillet R presenting a arcuate profile protruding convexly inward. The cross-sectional area of the blade is increased by providing the rectilinear surface portion (12). The heat capacity is increased compared with the conventional blade, due to the increased cross-sectional area of the blade. This in turn results in a decrease of the temperature difference due to the thermal stress. Thus, the thermal stress can be suppressed more effectively than with the conventional blade.