Thermo-structural analysis of HP stage gas turbine blades having helicoidal cooling ducts

In most of the practical gas turbines, the turbine blades of HP stage are usually too small to employ the turbine blade cooling techniques effectively. The growing need for effective blade cooling techniques is a direct consequence of the continuous quest for greater fuel economy. It is very well known that the thermal efficiency and power output of gas turbines increase with increasing turbine entry temperature (TET). The current TET level in advanced gas turbines is far above the melting point of the blade material. An attempt has been made in this paper to computationally analyze the thermo-structural analysis of HP stage turbine blade for effective cooling using innovative cooling passages within the blade. A helicoidal shaped duct has been analyzed corresponding to different cross section, diameters and pitch length. It is found from the analysis that helicoidal cooling duct of circular cross section of pitch length 6 mm radius 2 mm having turbulators (e/D = 0.08 and 0.75 mm rib thickness) and helicoidal cooling duct of elliptical cross section of pitch length 6 mm, major axis 2 mm and minor axis 2.5 mm result in better cooling effects and in turn reduces structural distortion.