This presentation deals with CONSTANT HEAD,CONSTANT SPEED,CONSTANT EFFICIENCY & CAVITATION in hydraulic turbines

1. Performance curves for turbines

2. Why?? Or Need??
• Turbines are designed for specific conditions of
Power , speed ,discharge called as designed
conditions
• But most of time of working turbines are required
operated at conditions other than designed
conditions
• Performance curves are important in order to
study performance of turbines at such conditions
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3. Types of curves
• Constant Head curves or Main curves
Head Maintained Constant
• Constant speed curves or operating curves
Speed Maintain Constant
• Constant efficiency or isoefficiency curves
efficiency maintained constant
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4. Constant Head Curves
• Procedure
For obtaining these curves test is carried out with
changing only load on turbine in steps &
corresponding Power, speed, discharge are
measured for a particular gate (or spear rod)
opening
Repeating the same procedure for different gate
opening values
After test ,Results are plotted in terms of following
3 graphs
1. Unit discharge Vs Unit speed
2. Unit Power Vs Unit speed
3. Efficiency Vs Unit speed
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5. Constant Head curve–For Pelton Wheel
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6. Constant Head curve–For Pelton Wheel
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7. Constant Head curve–For Pelton Wheel
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8. Constant head curves
for
REACTION TURBINES
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9. Constant head curves
for
Reaction Turbines
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10. Constant Speed Curves
• Procedure
This test is carried out maintaining speed
constant (by increasing discharge) while
increasing load in steps
After test ,Results are plotted in terms of
following 3 graphs
1. Efficiency Vs Discharge
2. Power Vs Discharge
3. Efficiency Vs part load conditionsPRATIK ACADEMY,SANGLI 9422378762 10

11. Constant Speed Curves
Discharge to
overcome friction PRATIK ACADEMY,SANGLI 9422378762 11

12. Constant Speed Curves
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13. Efficiency Vs % of Load
• As % of load increases efficiency also increases
• At full load conditions efficiency is maximum for
almost all turbines
• KAPLAN ,PELTON maintains high efficiency over
large load range
• Francis and propeller turbines give poor
performance at part load conditionsPRATIK ACADEMY,SANGLI 9422378762 13

14. ISO-Efficiency Curves
• These curves are obtained from speed Vs
efficiency & Speed Vs Discharge
• These curves gives zones of constant
efficiency and predicting performance of
turbine at various efficiencies
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17. PRATIK ACADEMY, SANGLI
Dear All , follow below link to find video lecture on
“Hydraulic Turbine Performance Curves”
• https://www.youtube.com/watch?v=LeQVz0vSBjw&list
=PLM38cEkdDRfTXmEB49EiP6WQzCkizLbsx&index=22
Cavitation in Hydraulic Turbines
• https://www.youtube.com/watch?v=5dqJkkaEotk&list=
PLM38cEkdDRfTXmEB49EiP6WQzCkizLbsx&index=23
Please Like and subscribe Our Channel
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18. At installation
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19. CAVITATION !!!
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20. CAVITATION !!!
• Mean???
• Why???
• Where???
• Effects???
• How to avoid??
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21. • Formation ,growth and collapse of bubbles of water @ low
pressure regions of machine
• Pressure at section falls below saturation pressure
corresponding to given temperature
• low pressure regions such as turbine outlet and draft tube
inlet
• vibration, noisy operation, hydraulic losses ,erosion of
surface
• controlling discharge pressure ,using high strength
materials ,selecting proper speed of turbinePRATIK ACADEMY,SANGLI 9422378762 21