Valve simulation across the full opening range
Know the flow coefficient, pressure drop and cavitation risk of your valve at every opening, and the forces the trim and body must carry, before a prototype goes on the flow rig.
A valve is judged on a handful of numbers: its Cv or Kv, the shape of its flow characteristic, the conditions at which it starts to cavitate and the thrust or torque needed to move it. Finding those numbers by test means a machined prototype and time on a flow rig for every variant. If the characteristic comes out wrong, or the trim cavitates at part opening, the fix is another prototype.
More about valve simulation
Valve CFD predicts the flow through the body and trim at each opening you choose, giving pressure drop, flow coefficient and the inherent characteristic as a curve. It shows where the jet leaves the seat, where pressure falls lowest and where the flow separates downstream. The same pressure field then becomes the load for a structural study of the plug, disc, stem and body, so actuator sizing and wall thickness are set from the same answers.
Openings, seat profiles and cage designs can be swept in one study, and the preferred seat profile or cage arrives as a modelled part that can go straight into the detailed design, drawings and production of the valve.
Typical valves: globe valves, ball valves, butterfly valves, gate valves, check valves, pressure-reducing and relief valves, and solenoid-operated valves for water, process, hydraulic and gas service.
What a valve study tells you
What is the Cv or Kv at each opening?
The flow coefficient from near-closed to fully open, plotted as the inherent characteristic, so you can see whether it is linear, equal percentage or something in between.
How much pressure does the valve cost the system?
Pressure drop at your design flow and the loss coefficient of the body when fully open, which feeds directly into pump or compressor sizing.
Will it cavitate or flash?
Where local pressure falls to the vapour pressure of the fluid, at which openings and pressure ratios that happens, and whether those regions sit on the seat and trim or in the free jet downstream.
What force or torque does the actuator need?
Flow-induced force on a plug, or dynamic torque on a disc or ball, across the stroke. Added to the seat and packing friction you supply, it sizes the actuator with known margin.
Is the body strong enough at test pressure?
Stress and deflection in the body, bonnet and bolting at working and shell test pressure, set against the allowable stresses in the code or standard you specify.
What we model
Liquid and gas flow
Incompressible flow for water, oils and process liquids; compressible flow for air and process gases, including choked conditions at high pressure ratios.
Opening sweeps
A series of cases from near-closed to fully open, so the characteristic curve is built from predicted points rather than interpolated between two.
Cavitation risk
Regions where pressure falls towards vapour pressure, with a cavitation index for each operating point to compare designs and openings on the same basis.
Trim and seat geometry
Plug contours, cage port shapes, multi-stage pressure-reducing trims, disc profiles and ball port shapes compared on capacity, characteristic and jet velocity.
Hydrodynamic loads
Pressure-integrated forces on plugs, discs and balls, and the resulting stem thrust or shaft torque at each opening.
Body and bonnet stress
Linear and non-linear stress in the pressure boundary, bolted joints and seats under internal pressure, pipe loads and bolt preload.
Thermal and fatigue loading
Thermal gradients in hot service and fatigue from pressure or operating cycles, for valves that open and close many times in their life.
Before you start
What to send us
- CAD of the body, trim and seat, with the stroke or rotation defined (STEP or native)
- The fluid and its temperature, plus density, viscosity and vapour pressure if it is uncommon
- Inlet pressure and either outlet pressure or flow rate for each case
- Openings of interest and the target flow characteristic
- Materials of the body, trim and bolting, with design and test pressures
- Pipe sizes and any fittings close upstream or downstream of the valve
How does CFD give a Cv value?
The study predicts pressure drop at a known flow rate for each opening. Kv follows from Kv = Q × √(SG/Δp), with Q in m³/h, Δp in bar and SG the specific gravity relative to water, and Cv is about 1.16 times Kv.
Can you predict cavitation damage?
We show where and when local pressure reaches vapour pressure and how close each design runs to that point. Erosion rates are a separate question, but moving low-pressure zones off the trim is usually what prevents the damage.
Do gas valves need a different approach?
They need a compressible model, because density changes through the valve and the flow can choke. Mass flow then stops rising as outlet pressure falls, which a liquid-style Cv calculation would miss.
Do we need separate CAD for every opening?
Not usually. If the trim moves by a simple translation or rotation, the openings can be set from one model and the travel you give us.
Can simulation replace flow testing?
No. It narrows the design to one or two candidates and tells you what to expect, so the test confirms a design rather than searching for one. Published ratings should still come from test where your customers or standard require it.
Send us your valve
