BISOPE series
45- A Collection of Vibration Causes of Fluid Machines
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In rotating machines, vibration occurs due to
centrifugal force due to mass imbalance and friction and impact between solids,
but there is another source of vibration. It is self-excited vibration caused
by friction between a solid and a fluid. This self-excited vibration is a type
of nonlinear vibration that is difficult to predict and is accompanied by
various causes and results. The root cause is that dynamic loads (mass and
velocity) also exist in the fluid.
Representative fluid machines have a fan and a pump, and
are classified according to whether the transported fluid is gas or liquid.
Blower (more than 0.1kg/m²) and Compressor (more than 1kg/m²) are also called
names.
Types of Fluid Vibration
Fluid vibration occurs in various ways, such as when the
fluid is caused by an ideal balance of pressure, when irregular vibration is
induced by the occurrence of turbulence, or when it is generated on the rear
surface by friction with a solid.
The vibration time waveform shows irregularity, and the
form of the spectrum has various expressions, such as when floor noise is
large, when a frequency group is formed over a certain period (wide band), or
when it appears as narrow-band discrete frequencies. The following table
summarizes various phenomena of fluid vibration.
|
type of vibration |
Causes and Symptoms |
