Stress-Strain State and Critical Rotational Velocities of Air Blower Rotor Part of a High Boost Engine

Abstract

The stress-strain state and critical rotation speeds of the air blower rotor part of highly forced engine are investigated. For this purpose, their parametric geometric and finite-element models are built. Due to the high speeds of rotation, the impeller disk acquires an umbrella-shaped deformed shape. This deformation can cause a gap to be selected between the impellers and the stator of the supercharger. In areas of abrupt change of shape on the impeller there is a concentration of stresses. In addition, the supercharger impeller is located cantilevered. This causes low critical speeds. These frequencies may fall within the operating range of angular velocities of the supercharger rotor. All these factors in the complex within a single calculation model were not previously taken into account. Instead, taking into account the dependences of stress, strain and critical velocity levels on the design parameters is of interest in the development of supercharger designs. In particular, the stiffness characteristics of the elastic rotor bearings were varied. The influence of these parameters on the critical rotation speeds of the rotor part of the air supercharger is determined. Recommendations have been developed for debugging from hazardous supercharger modes. In particular, it is proposed to reduce the radial stiffness of the shaft bearings by using elastic flexible rings. This can reduce critical rotor velocities beyond the operating range. In addition, a lighter material can be used to increase the strength of the impeller. It is also possible to limit the operating range of the angular rotational velocities of the rotor part of the investigated air blower. Analysis of the stress-strain state and the critical rotational velocities of the rotor were carried out on the basis of a unified generalized mathematical and numerical model. Keywords: rotor system, air blower, impeller, stress-strain state, critical rotation speed