Pump impeller simulation, from head curve to blade stress
Predict the head, efficiency and suction performance of a pump before it is cast, and see which blade, volute and inlet changes move the best efficiency point to where your system needs it.
A pump’s performance is set by geometry that is hard to change once patterns or tooling exist: blade angles, blade count, outlet width, the volute throat and the clearance at the cutwater. Testing each variant means casting or machining an impeller and booking time on a test loop, so most designs see only a few iterations. The result is often a pump that meets its duty point but runs less efficiently than it could, or cavitates earlier than it should.
More about pump impeller simulation
Pump impeller simulation models the flow through the inlet, the rotating impeller and the volute or diffuser at each flow rate you choose. It gives head, hydraulic efficiency and shaft power as curves, showing where the best efficiency point falls and how the pump behaves at part load. Pressure on the blade surfaces shows where cavitation is most likely to start, and loads from the flow study, with the centrifugal load, can be applied to a structural model of the impeller.
Each blade or volute variant gets a full curve, so designs are compared across the flow range as well as at the duty point. SixGate™’s engineers are designers first, and the comparison ends with a preferred impeller.
Typical pumps: end-suction and split-case centrifugal pumps, multistage high-pressure pumps, circulators, process and chemical pumps, submersible and dewatering pumps, and coolant pumps for electric vehicles.
What a pump impeller study tells you
What head and efficiency will it deliver?
Head, hydraulic efficiency and shaft power from part load to beyond the best efficiency point, with head H = Δp/(ρg) taken from the total pressure rise across the pump.
Is the best efficiency point in the right place?
Where peak efficiency falls relative to your duty point, and which outlet angle, outlet width or volute throat changes would move it.
How close is it to cavitating?
Where the lowest pressures sit on the blade leading edges and how they change with flow, so designs can be compared on how close they run to cavitation at the NPSH available in your system.
What loads reach the shaft and bearings?
Radial and axial hydraulic forces at each flow. In a single volute pump, the radial force grows as operation moves away from the best efficiency point.
Will the impeller crack or resonate?
Stress from centrifugal and pressure loads, and natural frequencies set against running speed and blade pass frequency.
What we model
Rotating impeller flow
The impeller in a rotating frame with the stationary inlet, volute or diffuser around it, as a steady or transient model depending on the question.
Performance curves
Head, power and efficiency over a range of flows and speeds, for radial, mixed flow and axial pumps, single stage or multistage.
Blade design
Inlet and outlet angles, blade count, wrap, thickness, leading edge shape and splitter blades compared on efficiency and suction performance.
Volute and diffuser
Throat area, cutwater clearance and diffuser vane design, which govern the best efficiency point, radial load and pressure pulsations.
Cavitation risk
Low-pressure regions on the blades and at the eye across the flow range, used to compare designs on how early cavitation would begin.
Impeller stress
Centrifugal and hydraulic loads on blades, shrouds and hub, including stress at blade roots and around balance holes.
Vibration
Natural frequencies and mode shapes of the impeller and rotor, compared with running speed, blade pass frequency and their harmonics.
Before you start
What to send us
- CAD of the impeller, volute or diffuser and inlet (STEP or native)
- Rated speed, duty point and the flow range of interest
- The liquid, its temperature and vapour pressure
- NPSH available in the installation, if suction performance matters
- Impeller material and any limits on diameter, speed or casting
- Existing test curves, if you are improving a current pump
Can you predict the effect of trimming the impeller?
Yes. The affinity laws give a first estimate, with flow, head and power scaling roughly as D, D² and D³, but trimming also changes the blade outlet and its gap to the cutwater, so efficiency shifts in ways those laws miss. Simulating the trimmed impeller shows the real curve.
Can simulation predict NPSH required?
Pumps are usually rated by NPSH3, the net positive suction head at which the pump’s head has fallen by 3%. A single-phase study does not give that figure directly, but it shows where the lowest pressures sit and how they spread as suction pressure falls, which is a sound basis for comparing inlet and blade designs on cavitation risk.
Do you model the whole pump or just the impeller?
Usually the inlet, impeller and volute or diffuser together, because the casing shapes the flow the impeller sees. Wear ring and balance hole leakage can be added where efficiency or axial thrust is the question.
Can you study viscous liquids as well as water?
Yes. Oils and other viscous liquids reduce head and efficiency compared with water, and simulating the actual liquid shows by how much at your duty point.
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