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Axial Fan High Reliability Requirements

Oct 10, 2017

With a large number of large-capacity thermal generator set to put into production, Axial Fan axial fan with its large flow, small start-up torque, the advantages of the wind duct system change adaptability to gradually replace the centrifugal fan become mainstream. Axial-flow fans have 2 kinds of regulating modes of movable leaves and static leaves. The movable vane adjustable axial fan can change working condition by changing the angle of work blade. No river closure loss, high efficiency, but also to avoid a small flow under the conditions of instability, but its complex structure, the stability and reliability of the adjustment device requirements are higher, Axial Fan the manufacturing accuracy requirements are high, prone to failure, So it is generally used only for air blower and primary fan. The static vane adjustable axial flow fan can change the working condition by changing the flow area and the inlet airflow direction, but its structure is simple and the failure rate of the regulating mechanism is very low, so it is generally used in the bad working environment.

With the wide application of axial-flow fan, the vibration problem corresponding to its structural characteristics is gradually exposed, Axial Fan which is not present or uncommon on centrifugal fan. In this paper, some characteristics of vibration and its causes are summarized and analyzed by summarizing the cases of abnormal vibration of various axial-flow fans.

The movable vane adjustable axial flow fan can change the operating condition of the fan by adjusting the opening degree of the moving vane on line. This is mainly dependent on the hydraulic control mechanism in the hub to achieve, each blade angle adjustment involves a series of adjustment components, so the installation of the components, coordination and parts of the deformation, wear requirements are higher, Axial Fan The hydraulic dynamic vane regulation system structure is shown in Fig. 1. Influence of dynamic vane regulating structure on vibration the main part of the single stage impeller blade opening different steps, two-stage impeller of the blade opening is not synchronized and adjust the parts themselves eccentric 3 aspects.

Single-stage impeller partial blade opening is mainly due to sliding block wear, adjusting rod and crank with loosening, petiole guide bearings and thrust bearings caused by rotation. These components are the driving mating parts between the hydraulic cylinders to the moving blades,Axial Fan will cause some of the fan blade opening is not in place, and the fan blade weight and installation radius are large, some of the fan blade opening inconsistent will produce a serious imbalance in quality, resulting in a high speed fan vibration.

1 The vibration spectrum and ordinary mass are unbalanced, vibration fault spectrum in the main frequency components, at the same time, some of the blade synchronization will produce a certain amount of air pulsation, so that the vibration spectrum of the blade through the frequency and its harmonic, Axial Fan some parts of the wear and loosing will have a certain non-linear impact, so that the vibration spectrum of high-frequency higher harmonic components, This is relatively obvious in the spectrum of vibration velocity, Axial Fan which is almost not observed in the displacement spectrum.

2 The amplitude of the fan is unstable, the amplitude change mainly occurs in the dynamic leaf opening adjustment process, when the dynamic leaf opening degree is stable, the amplitude basically remains stable, Axial Fan sometimes changes gradually with the dynamic leaf opening degree change.

3 at the beginning of the speed to work speed, wind motor leaves open or small, the fan amplitude is generally small.