Flow Measurement · Glossary

What is Turbulent Flow?

Re above about 4000Flow Measurement

Turbulent flow is chaotic flow with eddies and mixing across the pipe, found at high Reynolds numbers.

Turbulent Flow Explained

Most industrial water, steam and gas flows are turbulent. Eddies mix the fluid across the pipe, giving a flatter velocity profile than laminar flow.

Most flow meters are calibrated for fully developed turbulent flow. Bends, valves and tees upstream distort the turbulent profile, which is why straight pipe runs and flow conditioners are specified.

Turbulent Flow: Typical Values

Average to centreline velocity	roughly 0.8 to 0.87, rising with Re
Friction factor	depends on Re and pipe roughness (Colebrook equation)

Calculators for Turbulent Flow

CalculatorReynolds Number CalculatorFree online calculator with formula and worked example.CalculatorFriction Factor CalculatorFree online calculator with formula and worked example.CalculatorPipe Pressure Drop CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is Turbulent Flow?

Turbulent flow is chaotic flow with eddies and mixing across the pipe, found at high Reynolds numbers.

What causes turbulence?

High velocity, large pipe size and low viscosity, which together give a high Reynolds number.

Does turbulence cause noisy readings?

Some fluctuation, yes. Damping in the transmitter smooths it; strong noise usually points to swirl or a disturbance close upstream.

Learn more on the blog

What factors affect the stability of flow meter readings?

A practical guide on instrumentationblog.in with more detail on turbulent flow and how it is applied on real plants.

Read Full Article

More Flow Measurement Terms

Flow termBernoulli's EquationBernoulli's equation states that pressure, kinetic and elevation energy along a streamline add up to a…Flow termBeta RatioBeta ratio is the bore diameter of an orifice, nozzle or venturi throat divided by the pipe internal diameter.Flow termDischarge CoefficientDischarge coefficient is the ratio of actual flow to the theoretical flow through a DP flow element.Flow termExpansibility FactorExpansibility factor corrects DP flow equations for the drop in gas density as gas expands through the…Flow termVena ContractaVena contracta is the point just downstream of an orifice where the jet is narrowest and the pressure is…Flow termPermanent Pressure LossPermanent pressure loss is the part of the DP across a flow element that is not recovered downstream and…

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