Rotating machinery simulation, from the flow to the shaft
Understand how a fan, pump, mixer or rotor moves fluid, what torque and power it draws, and whether its blades, hub and shaft will stand up to the loads at speed.
Rotating equipment is judged on two things at once: what it does to the fluid and what the fluid does to it. The flow sets the duty, the power drawn and the efficiency. The same flow, together with centrifugal load, sets the stresses in blades, hubs and shafts, and its pulsations can excite vibration that a steady-state view never reveals.
More about rotating machinery simulation
Rotating machinery simulation covers both sides. CFD with a rotating reference frame or a fully rotating mesh gives flow rate, pressure rise, torque and power across the operating range, including the effect of the housing, inlet and outlet the machine sits in. Loads from the flow study, with the centrifugal load, are then applied to the structural model for stress and deflection, and a modal analysis shows whether any natural frequency of the rotating parts sits near running speed or blade-pass frequency.
Design options are compared on flow, power and stress together, because a blade change that gains efficiency can also raise the stress at its root or move a natural frequency. SixGate™’s design engineers turn the results into specific geometry, such as a blade angle, hub section, tip clearance or stiffer mounting, which can go straight into the detailed design, drawings and production of the machine.
Typical equipment: industrial and cooling fans, blowers, process mixers and agitators, centrifugal and axial pumps, and the rotors, drums and impellers of food, water and process plant.
What a rotating machinery study tells you
Does it deliver the duty?
Flow rate and pressure rise at your operating points, including losses from the inlet, housing and outlet it is installed in.
What torque and power does it draw?
Shaft torque and power from the fluid loads, which sizes the motor, gearbox and coupling with a known margin.
Where is efficiency being lost?
Recirculation, blade separation, tip leakage and poor inlet conditions located in the flow, so the fix targets the cause.
Will the rotating parts carry the load?
Stress in blades, hubs, keyways and shafts from centrifugal and fluid loads, set against the material’s strength and fatigue properties.
Is there a vibration risk?
Natural frequencies of blades, impellers and shafts compared with running speed, its harmonics and blade-pass frequency across the speed range.
How well does a mixer circulate the tank?
Flow pattern, circulation and dead zones in a stirred vessel, with torque and power number at each impeller speed.
What we model
Rotating reference frames
Steady studies that represent the rotor in a rotating frame, suited to comparing designs across the operating range.
Transient rotor-stator flow
A fully rotating mesh for the interaction between blades and stationary parts, giving pressure pulsations and fluctuating loads.
Fans in their installation
Axial and centrifugal fans inside the enclosures, ducts or heat exchangers they serve, with installation effects included.
Mixers and agitators
Impellers in baffled or unbaffled tanks, with circulation, dead zones, torque and power draw.
Centrifugal stress
Stress and radial growth in blades, hubs and rotors at running speed and overspeed, including the interference fit of a hub on its shaft.
Modal and harmonic response
Natural frequencies, mode shapes and the response of rotating parts and their supports to running-speed and blade-pass excitation.
Fatigue from fluctuating loads
Cyclic stress from start-stop cycles and blade-pass pressure pulsations, assessed for fatigue life.
Before you start
What to send us
- CAD of the rotor, housing and surrounding flow path (STEP or native)
- Operating speeds, including overspeed and start-up cases
- Duty points, or a description of the system it serves
- Fluid properties, including viscosity for process fluids
- Materials for blades, hub and shaft
- Any known issues: vibration, noise, cracking or a shortfall in duty
What is the difference between a frozen rotor and a transient study?
A frozen rotor, or rotating reference frame, study holds the rotor at one position and is efficient for comparing designs. A transient study turns the rotor and captures the pulsations and fluctuating loads that drive noise and fatigue.
Can you assess an existing machine that keeps failing?
Yes. With the geometry, operating data and a description of the failure, we can show the loads and frequencies involved and propose a change that addresses the cause.
Can you include the motor or drive?
The motor is usually represented by its speed and torque characteristic. Its own electromagnetic and thermal behaviour is covered by our electric motor simulation work.
How does this differ from turbomachinery simulation?
Turbomachinery work concentrates on blade and stage design for aerodynamic or hydraulic performance. Rotating machinery studies cover the whole machine as installed, including torque, structural strength and vibration of the rotating parts.
Send us your rotating machine
