Mnc flow measurements by vinod thombre patil
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Flow measurement techniques
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Mnc flow measurements by vinod thombre patil
- 1. Flow MeasurementsFlow Measurements ByBy Vinod Thombre - PatilVinod Thombre - Patil
- 2. Obstruction MetersObstruction Meters Orifice Meters Venturi Meters Flow Nozzles
- 3. Flow through a NozzleFlow through a Nozzle 2211 21 222111 21 vAvA ibleincompress vAvA Avm mm = ρ=ρ ρ=ρ ρ= = 1 1 1 1 v A m ρ 2 2 2 2 v A m ρ Basic Equations: a.) Continuity: mass in = mass out b.) Bernoulli’s Eqn. Total pressure is constant throughout
- 4. pressuredynamicv 2 1 pressuretotalP pressurestaticP PPv 2 1 Pv 2 1 Pv 2 1 .constessurePrTotalP Bernoulli 2 0 02 2 221 2 11 2 0 =ρ = = =+ρ=+ρ +ρ= == Flow through a NozzleFlow through a Nozzle
- 5. ρ ∆ − = ρ ∆ − == ρ ∆ − = P2 A A 1 1 YCAQ FlowalReFor Ideal P2 A A 1 1 AvAQ RateFlow P2 A A 1 1 v 2 1 2 2 2 1 2 222 2 1 2 2 Flow through a NozzleFlow through a Nozzle
- 6. ∆P21 2 1 22 2 2 2 2 1 2 1 2 22 2 11 2 2221 1 2 1 2 1 2 1 2 1 2 1 ρρ ρ ρρ ρρ = −= −= −=−=∆ when A A v v A A v vvPPP Flow through a NozzleFlow through a Nozzle
- 7. Y = Compressibility Factor =1 for incompressible flow or when ∆P<< Pabs C= Discharge Coefficient =f(Re) and nature of specific flow meter ∆P Flow through a NozzleFlow through a Nozzle P
- 8. Flow through a Venturi MeterFlow through a Venturi Meter In a venturi, 0.95 < C < 0.98 Advantage: Pressure recovery Uses little power
- 9. Flow through a Venturi MeterFlow through a Venturi Meter C Re 2 x 105 µ ρ = 11vd e R 0.98 Based upon the conditions in the pipe approaching the meter
- 10. Back to the NozzleBack to the Nozzle P1 P2 P P1 P2
- 11. Shorter and cheaper than venturi But larger pressure drop. Thus, more power lost in operating. The Nozzle FlowmeterThe Nozzle Flowmeter C 0.86 0.98 103 105 Re
- 12. Flow Through an Orifice MeterFlow Through an Orifice Meter
- 13. Flow Through an Orifice MeterFlow Through an Orifice Meter P1 P2 P P1 d D
- 14. Flow Through an Orifice MeterFlow Through an Orifice Meter -Cheapest and Simplest -But biggest pressure drop and power lost (C~0.6 - 0.7) -Side Note: Pressure drop caused by friction and turbulence of shear layer downstream of vena contracta CM A A C = − 2 1 2 1 1 0.6 0.85 β=d/D0.1 0.8 Re 100k 5000 10k
- 15. Elbow Flowmeter
- 18. Rotameter, variable-area-flowmeterRotameter, variable-area-flowmeter Force balance Drag Force Gravity Buoyancy (usually negligible) cal use caluse mm ρ ρ = Derived on next slide
- 19. D MgA D Mg Am D Mg V Mg V DF VAm 2 2 22 2 2 ρ ρ ρ ρ ρ ρ == = == = For a fixed x-position, A is fixed. Then cal use caluse caluse mm mm ρ ρ ρρ = = Rotameter Equations
- 20. Turbine Flow MetersTurbine Flow Meters
- 21. Vortex meters operate on the principle that when a non-streamlined object is placed in the middle of a flow stream, vortices are shed alternately downstream of the object. The frequency of the vortex shedding is directly proportional to the velocity of the liquid flowing in the pipeline.
- 23. Based upon Faraday’s Law The fluid is the conductor, must be electrically conductive. E=BDVx10-8 E=voltage, volts B=magnetic flux density, gauss D= length of the conductor, cm V=velocity of the conductor, cm/sec Magnetic flowmeterMagnetic flowmeter
- 25. Coriolis Mass Flow MeterCoriolis Mass Flow Meter
- 26. Coriolis Mass Flow MeterCoriolis Mass Flow Meter Vibrating Flow Tube Fluid Force is Reacting to Vibration of Flow Tube End View of Flow Tube Showing Twist Twist Angle Twist Angle Flow Force Flow Force Flow Flow
- 27. Coriolis Mass Flow MeterCoriolis Mass Flow Meter