Balanceamento de sistemas rotativos sem massas de triagem

Abstract

Rotating machines are used in several industrial activities with great emphasis on energy generation, in which a series of characteristic problems can arise from a rotating system on flexible, or rigid, supports. In this sense, mathematical models representing the dynamic characteristics of rotors have been developed to simulate their operating conditions. However, a simple consideration of the shaft behaviour is not enough for representing the complexity of this type of machinery. Therefore, other components such as bearings must be also considered. Hydrodynamic bearings have lubricating fluid between its rigid parts in order to eliminate dry friction and decrease operating temperatures and wear of the surfaces. In addition to understanding the rotor’s characteristics, performance improvement and cost reduction are highly desirable. For these, fault detection and identification are paramount. Unbalance is the most common cause of undesirable vibrations in rotating systems. Even small unbalance masses can cause high vibration amplitudes due to its quadratic relationship with the rotating speed, which may be a significant impediment to the safe operation of the machine. Therefore, balancing is essential for any equipment. In this scenario, the modelling of rotating systems supported by hydrodynamic bearings becomes particularly interesting in the analysis of these systems, as well as the solution of the Reynolds equation. The Unbalance Response Function (FRD) is directly used to calculate the unbalance parameters. For this, optimization methods are employed to minimize the differences between the numerical vibrations added by noise (representing experimental tests) and just numerical ones. The proposed methodology has the potential to eliminate the use of trial masses during field balancing tasks, saving precious maintenance time, and is suitable for multi-plane balancing. The methodology presents good convergence, minimizing the errors found for all analyzed cases.