Effect of Scallop on the Performance of Radial-Type Turbine

The radial-type turbines have been used not only for aviation but also for small power generation. In particular, it is applied as a core part of the turbocharger used to improve the performance of the transportation engine. Recently, according to the rise of research on renewable energy, it is also widely used as a generator of the organic Rankine cycle. However, the axial thrust on the radial turbine applied to the organic Rankine cycle is greatly increased because the working fluid must not be leaked to the outside the turbine. Therefore, the purpose of this study is to investigate the reduction of axial thrust as well as the reduction of efficiency when a rotor of the radial-type turbine is scalloped. For this purpose, three rotors having different scallop ratios were designed and analyzed numerically with an non-scalloped rotor. As a result, when the scallop ratio was 0.45, the efficiency was reduced by about 4%, and the axial thrust was reduced to 29%.