An Optimized Modal Balancing Approach for a Flexible Rotor Using a Vibration Response While the Rotor Is Speeding Up

Liqing Li,Shuqian Cao,Yuanhang Hou

doi:10.1155/2022/5261279

Abstract

The modal balancing method (MBM) is an effective method for reducing the vibration caused by the unbalancing of a rotor. A rotor’s modal parameters, especially its modal shapes, need to be accurately calculated in this method. This paper proposes an optimized modal balancing approach for flexible rotors. The vibration modes of the rotor are first obtained with experimental modal analysis based on the rotor’s response signals while the rotor is speeding up. The rotor balancing strategy is subsequently optimized by the sensitivity analysis of the mode shapes. Orthogonal trial masses are obtained based on the orthogonality of each vibration mode, and the correction masses are finally calculated by using the influence coefficients of the trial masses. An experimental result is shown to demonstrate and validate that the proposed approach is able to achieve superior accuracy compared to the conventional MBM.

Highlights

Turbomachinery users are constantly concerned about the increased cost and possible downtime associated with the influence coefficient method (ICM) due to its limitations and difficulties in flexible rotor balancing [14, 15]
The selection of balancing planes is heavily dependent on the operator’s experience. e lack of rotor dynamic characteristics may lead to balance failure [16–18]. erefore, the application of the ICM in flexible rotor balancing is seriously restricted
Determining the mode shapes of a rotor is a key step for modal balancing, and these shapes are generally calculated with the finite element (FE) method

Summary

Introduction

A rotor is the core component of rotating machinery. e main vibration of rotating equipment is caused by the unbalance of a rotor. Determining the mode shapes of a rotor is a key step for modal balancing, and these shapes are generally calculated with the finite element (FE) method. Bertoneri [21] developed a dynamical balancing system by using the FE model to calculate the rotor vibration mode for the correction masses in balancing. Is method uses the vibration response and the accurate FE model of a rotor system to obtain the correction masses of a rotor. In most MBMs, a highly accurate FE model of a rotor is required to obtain the modal information. Irdly, the mode shape sensitivity analysis for the local mass changes of the rotor is used to optimize the balancing strategy in selecting correction planes, and the correction masses are calculated by using the MBM.

Modal Parameter Estimation for the Rotor

Correction Plane Optimization with Sensitivity Analysis

The Optimized Modal Balancing Approach

Experimental Validation

Modal Parameters of the Rotor

Experimental Results of the Rotor Balancing