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Pump
Integration, Inc., has the capability and experience to conduct a
complete rotordynamic analysis on any horizontal or vertical, single
or multistage pump. This process helps to diagnose the problem and
predict a suitable solution to avoid serious future machinery
problems. PII utilizes state-of the art finite element software
packages to calculate all relevant parameters and solutions of the
following categories:
LATERAL
ROTOR DYNAMICS
PII can model all types
of rotating machinery and accurately predict the critical speed(s),
stability, synchronous response, and time transient response. Our
engineering experience and technology provide a solution that
considers the geometry, material, gravity, rotary inertia,
gyroscopic effects, wear ring seals, and journal bearings. Each
report contains a detailed description of the following results:
STABILITY
ANALYSIS
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Natural
frequencies and mode shapes
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Growth factors/damping ratios
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Rotor orbit directions
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Bearing reaction forces
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Shaft weight, deflection, and slope
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Stability and critical speed maps
UNBALANCE RESPONSE
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Multiple
unbalance forces
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Magnitude
and phase
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Dynamic
forces and moments
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Vibratory
amplitudes and orbits
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Forces
and moments transmitted
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Foundation
vibratory amplitudes
TIME-TRANSIENT RESPONSE
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Gravitational and External force: sinusoidal, step, ramp, & pulse.
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Lateral amplitudes
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Rotor orbits
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Dynamic forces and moments
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Dynamic stresses
TORSIONAL VIBRATION
PII can also calculate the torsional natural frequencies, mode
shapes, and response of single rotors or entire mechanical drive
trains. Along with the basic shaft geometry we also take into
consideration multiple shaft branches, gear tooth flexibility,
external excitation forces, and synchronous motor start-up torque.
BEARING ANALYSIS
This program can model many different types of bearings including
plain journal bearings, grooved, lobed, tapered, and others. A
variable grid finite difference numerical method is employed for
obtaining a solution. The solution generates the associated
stiffness and damping coefficients of the bearings for a given
load/eccentricity. These solutions can help improve on bearing
stability and reduce vibration problems.
WEAR-RING COEFFICIENTS
Pumps normally have higher critical speeds than other rotating
equipment. This is due to the Lomakin Effect. The close running
clearances inside the pump provide additional rotordynamic stiffness
and damping. All our models account for this by calculating the
leakage and coefficients (Stiffness and damping) for turbulent flow
pump seals. The resulting stiffness and damping matrices are
included in the lateral rotor model for each individual seal
station.
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