Abstract
Unbalanced mass identification is important for rotor systems. Current methods normally use sensors, which only detect vibration in two-dimensional (2D) space. Actually, the rotor systems vibrate in three-dimensional directions. In this paper, a non-contact method is developed to identify unbalanced mass of rotor systems in 3D space. A stereo video system with a pair of synchronized high-speed cameras is established and a feature point is employed to replace traditional contact transducer for measurement. Checkerboard target on a vibration table is used to implement dynamic calibration. The proposed method is compared with eddy current method and laser displacement method. The comparison experiments verify the detection ability of the unbalanced mass for the proposed method. Overall, the proposed method can provide more information than 2D detection methods, which has the great potential for fault diagnosis of rotating machinery.
Highlights
Rotor systems play an important role in gas turbine, aircraft engine, industrial compressors, and many other machineries
The videometric measurement system is more intuitive for monitoring the operational status of rotor machinery because 3D motion of rotary structure is observed at the same time
The dominant frequency components are marked and the results show that the amplitude of the marked peak decreases with the adding unbalanced mass
Summary
Rotor systems play an important role in gas turbine, aircraft engine, industrial compressors, and many other machineries. A typical rotor failure is the nonconforming response problem caused by unbalanced mass. Measuring the unbalanced mass of rotating machinery under operating conditions is difficult. Most contact measurement methods are unavailable for operating rotor systems [2,3]. Traditional contact transducers are directly attached to the structure to measure vibrations, which results in unwanted mass-loading that affects the whole dynamic system. The non-contact sensors, typically eddy current sensors, measure the vibration in one- or two-dimensional dynamical responses for rotor systems. Based on the 1D or 2D vibration information, two groups of identification methods have been developed: model-based methods [4] and statistical methods [5]. The model-based methods, for example, the classical influence coefficient method [6]
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