Development of Methods for Reducing Aerodynamic Impact on Turbomachine Blades

The forced response under the action of aerodynamic forces is one of the main sources of high cycle fatigue in turbomachines impellers. Especially in the case of resonance, the vibrations of the blades caused by the gas flow can become dangerous. It is not always possible to avoid resonant states, therefore it is necessary to reduce the level of aerodynamic exciting forces acting on the working blades in operation. There are many factors that affect the intensity of aerodynamic impact in the working blades: gas temperature and pressure, rotor rotation speed, aerodynamic damping, geometric parameters of the nozzle array... On this basis, many authors have proposed and developed some methods: changing the operating conditions: geometric intentional detuning, asymmetric design of the stator blades and increased damping of the blades. This paper presents a literature review of methods for reducing the level of aerodynamic exciting forces on the working blades and a recommendation for further research. In this paper also were shown results of a numerical study on two variants of geometric intentional mistuning: a change in the angle of installation of the profile in the grid and the ratio of the steps of the working and guide blades.