FRANCIS TURBINE TEST RIG

FRANCIS TURBINE TEST RIG:OBJECTlVE: To study the operation of a Francis Turbine.

A1M: To determine the output power of Francis Turbine. To determine the efficiency of the Francis Turbine.

INTRODUCTION:Francis Turbine, named after James Bichens Fransis, is a reaction type of turbine for medium high to medium low heads and medium small to medium large quantities of water.The reaction turbine operates with its wheel submerged in water. The water before entering the turbine has pressure as well as kinetic energy. The moment on the wheel is produced by both kinetic and pressure energies. The water leaving the turbine has still some of the pressure as well as kinetic energy.

THEORY:Originally the Francis turbine was designed as a purely radial flow type reaction turbine but modern Francis turbine is a mixed flow type in which water enters the runner radially inwards towards the center and discharges out axially. It operates under medium heads and requires medium quantity of water.

DESCRIPTION:The Francis Turbine consists of spiral casing, an outer bearing pedestal and rotor assembly with runner shaft and brake drum, all mounted on a suitable sturdy cast iron base plate. A straight conical draft tube is provided for the purpose of regaining the kinetic energy from the exit water and also facilitating easy accessibility of the Turbine due to it locating at higher level than the tailrace. A transparent hollow Perspex cylinder is provided in between the draught bend and the casing for the purpose of observation of flow at exit of runner. A rope brake arrangement is provided to load the Turbine. The output of the turbine can be controlled by adjusting the guide vanes for which a hand wheel and a suitable link mechanism are provided. The net supply head on the turbine is measured by a pressure and vacuum gauge.

UTILITIES REQUIRED:1. Water supply (400 ltrs)2. 3 phase supply, 440 volt AC3. Drain4. Space required: 2.2m x 1 m

EXPERIMENT AL PROCEDURE:Starting Procedure: 1. Clean the apparatus and make Tank free from Dust.2. Close the drain valve provided.3. Fill Sump tank 3/4 with Clean Water and ensure that no foreign particles are there.

4. Fill manometer fluid i.e. Hg. in manometer.5. Now switch on the Main Power Supply (440 V AC, 50 Hz).6. Switch on the Pump with the help of Starter.7. Open the Air release Valve provided on the Manometer, slowly to release the air from

Manometer.8. When there is no air in the manometer, close the Air release valves.9. Now regulate the Guide Vanes position with the help of a Hand Wheel provided for

this purpose.10. Now turbine is in operation.11. Regulate the discharge by regulating the Guide Vanes position.12. Load the turbine with the help of hand wheel attached to the Spring Balance. 13. Note the Monometer Reading.14. Note Pressure gauge reading.15. Note Vacuum gauge Reading. 16. Note the RPM of the Turbine.17. Note the Fixed and Adjustable Balance Readings.18. Repeat the same experiment for different load and different discharge.

Closing Procedure:1. When the experiment is over, first remove load on dynamometer. 2. Close the ball valves provided on manometer.3. Switch OFF Pump with the help of starter.4. Switch OFF main power supply.

SPECIFICATION:

Pump = Centrifugal typePump = A.C. 15 HP / 13.75KW, 3 Phase, 440 Volts.Spring Balance = 10kgRunner diameter = 162 mmNos. of Guide Vanes = 10 nos

FORMULAE:

Total Head H = 10 * P m of waterDischarge Q = A * V (m3/sec)

Where V = Cd √ [2gh {(m / w)-1}] (m/sec)

Turbine Input = w Q H / 75 watt

Turbine output = [(w1 + w3 - w2) Re 2N] / 4500 HP

efficiency % = (output / input) 100

Re = (D + 2d) / 2 = 0.165 m

OBSERVATION & CALCULATION:

DATA:Flow measurement = Pitot tube in 108 mm diameter pipeA = Cross-section area of pipe = 0.00916 m2

g = Acceleration due to gravity = 9.81 m/s2

m = Density of water = 1000 kg.m3w = Density of Manometer fluid i.e. Hg = 13550 kg/m3D = Diameter of Brake Drum = 0.3 mCpitot = Co-efficient of pitot tube = 0.98d = Diameter of rope = 15 mmRe = Effective radius = 0.165 mW3 = Weight of hanger = 1.0 kg

OBSERVATION TABLE:

S. N. RPM (N) Pr. Gauge reading P (kg/cm2)

Differential Pr. H (m)

Dead weight w1 (kg)

Spring balance w2 (kg)

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CALCULATION TABLE:

S.N. Total Head H

Velocity v

Discharge Q

Output Input Turbine Efficiency %

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NOMENCLATURE:

A = Cross-sectional area of pipeP = Pressure gauge reading, kg.cm2

V = Vacuum gauge readingm = Density of water w = Density of Manometer fluid i.e. Hg