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Axial Flow Impeller Simple Structure Data Requirements Are Very High
Aug 04, 2017

Axial Flow Impeller, the use of a very wide range, that is, with the fan axis of the same direction of the air, such as electric fans, air conditioning fan is the way the fan running fan. It is called "axial flow" because the gas flows parallel to the fan shaft. Axial Flow Impellers are often used in situations where the flow rate is high and the pressure is low. The Axial Flow Impeller is fixed and moves the air. Axial Flow Impeller is mainly composed of fan impeller and housing, simple structure but the data requirements are very high,

Ordinary Axial Flow Impellers can be used in general factories, warehouses, offices, residential and other places of ventilation, can also be used for chillers (air coolers), evaporators, condensers, spray down, etc., there are mining shaft Flow fan,

Anti-corrosion, explosion-proof Axial Flow Impeller with anti-corrosion materials and explosion-proof measures, and match the explosion-proof motor can be used to transport explosive, volatile, corrosive gas,

Require the axial flow of the gas should be no significant dust, no sticky and fiber material; motor direct-type temperature does not exceed 40 ℃, belt drive type temperature does not exceed 60 ℃. The amount of dust transported to the gas shall not exceed 150mg / m3,

Axial Flow Impeller is mainly composed of impeller, chassis, motor and other components, the use of steel and the stent duct connection. One of the anti-corrosion type Axial Flow Impeller impeller, the chassis are made of glass fiber reinforced plastic, other types of Axial Flow Impellers are generally made of steel.

With the construction of a large number of large-capacity thermal power units put into operation, the Axial Flow Impeller with its flow, starting torque is small, the advantages of adaptability to the wind system changes gradually replace the centrifugal fan mainstream. Axial Flow Impellers have two kinds of adjustment methods: moving leaves and stationary leaves. Adjustable axial flow fan by changing the angle of work leaves to change the working conditions, there is no closure loss, high efficiency, but also to avoid instability in the small flow conditions, but its complex structure, the stability of the regulator and Reliability requirements are higher, the manufacturing accuracy requirements are higher, prone to failure, it is generally only used for blowers and a fan. The adjustable axial flow fan is changed by changing the flow area and the inlet airflow direction to change the working conditions. There is a loss of the cutoff, but its structure is simple and the failure rate of the regulating mechanism is very low. Therefore, it is generally used for the induced draft fan with poor working environment.

With the extensive application of Axial Flow Impellers, vibration problems corresponding to their structural characteristics are gradually exposed, and these problems are not present or less common in centrifugal fans. In this paper, we summarize the cases of abnormal vibration faults of various Axial Flow Impellers, and summarize some of the vibrations and their causes.

Adjustable fan-flow fan through the line to adjust the opening degree of the fan to change the operating conditions of the fan, which mainly rely on the wheel of the hydraulic control mechanism to achieve the adjustment of the various blade angle involves a series of adjustment components, Parts of the installation, with the parts of the deformation of their own, high wear requirements, hydraulic leaf adjustment system structure shown in Figure 1. The influence of the structure of the blade on the vibration is mainly that the partial leaf opening of the single stage impeller is not synchronized, the blade opening degree of the two impeller is not synchronized and the eccentricity of the regulating part itself is three.

Single-stage impeller part of the blade opening is not synchronized due to the slider wear, adjust the rod and crank with loose, petiole-oriented bearings and thrust bearings caused by poor rotation. These components are hydraulic cylinder to the moving blade between the moving parts, will lead to part of the fan blade opening is not in place, and the fan blade weight and installation radius are larger, part of the fan blade opening inconsistency will produce serious quality imbalance, Resulting in significant vibration of the fan at high speeds.

Single-stage impeller part of the blade opening is not synchronized caused by the main vibration characteristics are as follows.

1) vibration spectrum and general quality are unbalanced, vibration fault spectrum is mainly frequency components, while some of the leaves will not produce a certain degree of air flow pulsation, so that the vibration spectrum of the blade through the frequency and its harmonics, part of the wear and tear And loose will produce a certain degree of non-linear impact, so that the frequency spectrum of high frequency harmonic components, which in the vibration frequency spectrum was relatively obvious in the displacement spectrum is almost impossible to observe.

2) The amplitude of the fan is unstable, and the amplitude change mainly occurs in the process of adjusting the opening of the leaf, and the amplitude is stable when the stability of the moving blade is stable, and sometimes changes with the change of the leaf opening.

3) just to speed to the working speed, the fan is not open or open the smaller, the fan amplitude is generally small.