Increase of an Impeller Machine Efficiency by Proper Selection of a Blade with Minimal Aerodynamic Drag

Abstract

Abstract This work deals with a problem of an impeller machine efficiency increase by proper selection of blade geometry. Impeller machines like fans, turbines, compressors, pumps etc. are the most commonly used devices in power, extractive, oil and gas and other branches of industry. It is well known that surface boundary layer formed on a blade surface is unstable that can results in separation, vortex structures formation and subsequent loss of a total pressure. All this phenomena decrease device efficiency and can cause emergency situations. In this work a mathematical model and corresponding numerical algorithm for fluid flow around a single blade or blade cascade are developed. This approach provides the possibility of blade profile optimization and device efficiency increase. Two fluid flow models are considered: Potential fluid flow around a blade or in blade cascade with subsequent boundary layer parameters and separation points exact location calculations (methods 1, 2).Numerical simulation of a blade profile or blade cascade based on solution of Navier-Stokes equations for viscous and turbulent flows (methods 3). Solution strategy is based on sequential application of both mentioned above methods: starting from very fast potential flow calculation (few seconds are needed to obtain a results) and continuing with full set of Navier-Stokes equations simulation refining preliminary obtained results that can take dozens of hours. Such algorithm is especially important for problem of profile optimization while fast enough shift of a separation point in trailing edge direction is one of main goals. Subsequent profile improvement via solution of viscous fluid flow problem demands noticeably smaller time in comparison with direct profile optimization started from viscous Navier-Stokes equations simulation. Obtained results verification by available experimental data shows high efficiency of the proposed scheme. This approach applicability can be significantly expanded to areas where hydrodynamic processes accompanied by separation are of especial importance.