Study and Analysis of a Power Turbine Preliminary Design for a Small Turboshaft

This work describes the continuous study that is being done in a small gas turbine that can be used for power generation purposes. Previous studies were conducted aiming to develop a gas generator able to be used in both applications, as a turbojet or as a turboshaft. The gas generator was designed, manufactured and is still under test. The thermodynamic cycle calculation was evaluated as a project-based class, hence, a power turbine was specified and its requirements were determined. The outlet conditions from the gas generator were used to perform the preliminary size of the power turbine. At this phase, the students must use 1D design models considering loss modeling to improve the machine design prediction. The meanline technique was used and the calculations at leading and trailing edges were extrapolated from hub-to-tip, using vortex design methods. With the airfoil stacking for each blade row was possible to determine the 3D geometry of the single stage axial flow turbine. This geometry was assembled in a CAD software to start the mesh generation procedure. After this step, a commercial CFD software was used to calculate the continuity, momentum and energy equations from fluid mechanics. The flow was considered fully turbulent and the two-equation SST turbulence model was set to determine the flow eddy viscosity. The results from preliminary design and 3D techniques were compared and evaluated to complete the first round of the design phase. In this work, experiences from the project-based class on turbomachinery design are described together with the challenges and difficulties that appeared during the project.Copyright © 2015 by ASME