A comprehensive approach to the analysis of the static and dynamic strength of the rotor of the smoke cleaner

Abstract

The work describes the process of assessing the static and dynamic strength of the rotor of an axial smoke exhauster with twin blades which allow significantly increasing its efficiency. To build a calculation model for the strength analysis, the geometric model was simplified by removing bolted connections, slicing small surfaces, as well as modeling welds in the form of roundings and chamfers. Such simplifications made it possible to build a high-quality finite-element mesh with the sufficient accuracy for performing engineering calculations. Calculation models include a finite-element model of one sector of cyclic symmetry of the impeller of the smoke exhauster, which is used to more accurately determine its stress-strain state and local maximum stresses in the places of their concentration in the root sections of the blades and in the places where they are connected by jumpers due to the action of centrifugal forces, aerodynamic loads on the blade and thermal loads due to wheel heating, as well as a finite-element model of the entire rotor with a less detailed meshing of the impeller, which in this case plays the role of a mass-inertia element, and a more detailed meshing of the shaft to analyze its static strength and reactions in bearing assemblies from the action of gravity and determine natural frequencies and mode shapes of rotor vibrations and the possibility of resonances with multiples of the frequency of excitating loads. The analysis of the static strength of the impeller and the rotor shaft of the smoke exhauster was performed by comparing the von Mises equivalent stresses with the allowable stresses, and the analysis of the dynamic strength of the smoke exhauster rotor was performed by determining the level of detuning of the natural frequencies of vibrations from multiples of the frequency of the excitating load, which in this case was assumed to be the centrifugal forces acting on the unbalance of the rotating rotor. A detailed analysis of the results of calculations made it possible to establish that the elements of the smoke exhauster rotor meet the requirements of static strength under the action of all possible types of loads, and the natural frequencies of the rotor oscillations have a sufficient level of detuning from multiples of the frequency of the excitating load. In this way, a conclusion was made about the static and dynamic strength of the rotor of the smoke exhauster, which affect its resource and durability of operation in the nominal mode.