Abstract
In recent years, the flow characteristics research of the interstage region in counter-rotating axial fans in terms of fluid dynamics has attracted much attention. Especially, the dynamic relationship between interstage pressure pulsation and blade vibration in counter-rotating axial fans has not yet been clarified. This paper performs the signal processing method of wavelet decomposition and reconstruction in time-frequency analysis process. Under different flow conditions, weak-coupling numerical simulation program is employed to analyze the fluid-structure coupling interaction between interstage pressure pulsations and blade vibrations in counter-rotating axial fans. The results indicate that the fluid-structure coupling interaction field in the interstage of counter-rotating axial fans mainly excites the first-order vibration of the second-stage blade. At the same time, the consistency between the pulsation frequency and the vibration frequency of the airflow reflects the good coupling property. Two stage blades cut the airflow to cause field changes and airflow pulsation, and then, airflow pulsation causes blades deformation and produces vibrations of the same frequency at the blade. The deformation of the blades, in turn, causes the flow field changes. Rotating stall, vortex movement and breakdown produced low-frequency airflow pulsation and vortex vibration of the blade.
Highlights
Rotation machinery, such as steam turbine, gas turbine, fan, compressor and so on, are employed in many industries [1, 2]
The aerodynamic performance of the fan measured by u-shape tube manometer, vibration measured by KD1005 acceleration sensor and uT4304 multifunction pre-amplifier, airflow pulsation measured by CYB11 pressure sensor and pre-regulator, noise measured by AWA14425 microphone and AWA14604 pre-amplifier
The signal processing method of wavelet decomposition and reconstruction in time-frequency analysis process are presented experimentally and numerically in the contrarotating fan, and the following conclusions can be received that: 1. The instability of the flow field initially appears around the blade tip, and the flow regime of the blade tip is more complex than that of the blade root, which is mainly caused by the Contra-rotating fan interstage pressure pulsation and blade vibration based on wavelet reconstruction existence of a blade tip leakage flow
Summary
Rotation machinery, such as steam turbine, gas turbine, fan, compressor and so on, are employed in many industries [1, 2]. Counter-rotating axial fans, compared with general axial fans, can provide higher transmission efficiency, higher counter air volume and smaller structure size, which will become increasingly more important in axial fan develop process. The failure rate of counter-rotating axial fans is higher than that of general axial fans because of the particular nature of the structure, which is always the main source of decreased efficacy [3]. It is very important to improve the reliability of counter-rotating axial. Contra-rotating fan interstage pressure pulsation and blade vibration based on wavelet reconstruction no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
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