Parametric Study & Performance Improvement of Centrifugal Compressor Impeller of a Turbo-shaft Engine Using 3D Numerical Simulation

In this research, the centrifugal compressor impeller of a turbo-shaft engine is studied. For this purpose, at first, its geometric specifications are exactly measured and then, the impeller geometric model is generated in the Blade-Gen module of Ansys software. This geometry is then reticulated in Turbo-Grid module and is numerically analyzed by applying the boundary conditions that can be obtained from the engine performance. The results are presented in the form of pressure ratio and efficiency curves versus the mass flow. After grid independency, some geometrical parameters (e.g. meridional profiles pages, the axial length and so on) that affect the performance of the compressor are investigated. Finally, the effects of geometric changes on the compressor performance curves are considered and the optimum compressor geometry equivalent to one with higher ratio of pressure and efficiency is introduced. In the modified compressor, the radial region of impeller to the whole ratio is 0.22 and the angle between the end of shroud wall and the vertical line is 6 degrees; moreover, the axial length of impeller increases by 5mm. By applying these modifications to the current compressor, the compressor efficiency and pressure ratio increases by 2.4 and 0.86 percent, respectively.