ultrasonic flowmetering
DESCRIPTION
Ultrasonic FlowmeteringTRANSCRIPT
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Ultrasonic Flowmeters
M Suresh, CRE.
F l u i d C o n t r o l R e s e a r c h I n s t i t u t e
Bringing Research Resources to Industry
Coverage
• Basic Requirements in Flowmeters
• Ultrasonics and its behaviour in media
• Flow measurement principles by
Ultrasound
• General Installation criteria
• Diagnostics
� High Accuracy
� High Turn-Down Ratio
� Low Cost
� Low Pressure Loss
� No Moving Parts
� Ability to Calibrate
� Easy Integration with Piping System
� Resistant to Corrosion and Erosion
� Low Sensitivity to Dirt or foreign Particles
� High Accuracy
� High Turn-Down Ratio
� Low Cost
� Low Pressure Loss
� No Moving Parts
� Ability to Calibrate
� Easy Integration with Piping System
� Resistant to Corrosion and Erosion
� Low Sensitivity to Dirt or foreign Particles
Desirable: A Flowmeter that has..
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1. Coriolis vibrating tube
2. Electro-magnetic
3. Flow Nozzles
4. Orifice plate
5. Venturi
6. Elbow Tap (Elbow Meter)
7. Pitot Tube
8. Velocity-Area Averaging
9. Positive Displacement
10. Reciprocating Piston
11. Oval Gear
12. Turbine
13. Nutating Disk
14. Rotary Vane
15. Target
16. Thermal Dispersion
17. Ultrasonic Doppler
18. Ultrasonic Transit Time
19. Variable Area
20. Vortex
21. Swirl
22. Fluidic Oscillation
(Coanda Effect)
23. Cross-Correlation Method
Flow Metering in Conduits
Ultrasonics• Ultrasound: sound of frequency > 20 kHz
• A sound wave is a pressure disturbance that
travels through a medium by means of particle-to-
particle interaction.
• Speed of wave depends upon properties of the
medium.
� inertial properties (e.g density)
� elastic properties (e.g Modulus of Elasticity)
• �����, � = λ; Speed = frequency x wavelength
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• Generated using piezo-electric materials.
• Piezo-electricity:
� Observed as occurrence of electric dipole moments
in crystalline solids
� Charge accumulates in crystal in response to
applied mechanical stress
� Conversely, applying electric potential causes
material to undergo deformation
Piezo-electricity
• First demonstrated by Pierre Curie and Jacques
Curie, 1880
• Naturally occuring materials:
� tourmaline, quartz, topaz, cane sugar, Rochelle
salt (sodium potassium tartrate tetrahydrate)
• Converse piezo-electicity: Gabriel Lippmann, 1881
• Woldemar Voigt , 1910: Lehrbuch der Kristallphysik
(Textbook on Crystal Physics)
Piezo-electric Materials
• Paul Langevin, 1917, developed ultrasonic
submarine detector
• World War II: piezoelectric constants for synthetic
materials (ferroelectrics) >> natural materials
• Piezo Ceramics e.g. barium titanate (BaTiO3), lead
metaniobate (PbNb2O3), lead zirconate titanate
(PZT), etc.
• Polymer material e.g. PVDF
Piezo-electric for Ultrasonics
Acoustic impedance
piezoelectric ceramics 2.6 × 10.7kg/m2s,
air 4.3 × 10.2kg/m2s.
Match acoustic impedance by bonding acoustic matching
layer to piezoelectric ceramics