Experiment No 04 Francis Turbine 225wc

c cc c PERFORMANCE CHARACTERSTICS OF FRANCIS TURBINE .

cc: To study the operation of a Francis Turbine and determine the output power and efficiency of Francis Turbine.

Francis Turbine named after James Bichens Francis, 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 wheels 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.

c 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 centre and discharges out axially. It operates under medium heads and requires medium quantity of water.

c cc The present set up consists of a runner. The water is fed to the turbine by means of Centrifugal pump, radially to the runner. The runner is directly mounted on one end of a central SS shaft and other end is connected to a brake arrangement. The circular window of the turbine casing is provided with a transparent acrylic sheet for observation of flow on the runner. This runner assembly is ed by thick cast iron pedestal. Load is applied to the turbine with the help of brake arrangement so that the efficiency of the turbine can be calculated. A draught tube is fitted on the outlet of the turbine. The set up is complete with guide mechanism. Pressure and vacuum gauges are fitted at the inlet and outlet of the turbine to measure the total supply he ! "#$ It is of close grained cast iron with integral legs.

% &'(#)*#% )##% It is of gunmetal designed for efficient by a hand wheel through a link mechanism. External dummy, guide vanes working inside the turbine. + ,' It is of steel accurately machined and provided with gunmetal sleeve at the stuffing box.

!! % #$" It is of double a row deep groove rigid type in the casing and double row self aligning type in the bearing pedestal both of liberal size. ,' %#- It is provided at the exit of the runner with a transparent cylindrical window, for observation of flows the runner. To the bend is connected a straight conical draft tube of mild steel fabrication.

.% #$%/%#' It consists of a machined and polished cast iron brake drum, cooling water pipe, discharge pipe, internal water scoop, dead weights, spring balance rope brake, etc arranged for loading the turbine. *"%0 '(#1#-(2 A transparent Perspex hollow cylinder window for observation of flow age, through the runner is provided in between the casing and draught tube.

cc3c #&")*#%% &'(#)*#% i) Power output : 5HP ii) Speed: 1250 rpm iii) No. of guide vanes: 10 iv) Brake drum diameter: 300mm v) Rope diameter: 15mm

)!4)/"%' i) Power required : 15HP ii) Type: Centrifugal !(2% ")#$#' i) Diameter of Inlet: 100mm ii) Diameter of throat: 59.16 mm iii) Venturi meter constant : K= 0.013 (Q = K ¥h) where h in meter of water

c cc cc ' '#$(&%-)% 1. Clean the apparatus and make tank free from dust. 2. Close the drain valve provided. 3. Fill sump tank ¾ with clean water and ensure that no foreign particles are there. 4. Ensure that there is no load on the brake drum. 5. Switch ON the pump with the help of the starter. 6. Open the Pressure gauge valve slowly. 7. Now turbine is in operation. 8. Apply load on hanger and adjust the spring balance load by hand wheel just to release the rest position of the hanger. 9. Note the manometer reading, pressure gauge reading and vacuum gauge reading. 10. Measure the RPM of the turbine. 11. Note the applied weight and spring balance reading. 12. Repeat the same experiment for different load. 13. Regulate the discharge by regulating the guide vanes position. 14. Repeat the experiment for different discharge. !("#$(&%-)%: 1. When the experiment is over, first remove load on dynamometer. 2. Open the by- valve. 3. Close the ball valves provided on manometer. 4. Switch OFF pump with the help of starter. 'm m





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1) Efficiency =

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2) Brake Power =

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Where, T= Torque in N.m T= ( W1-W2 )x Re , Where Re= (D + d) / 2 is the effective radius of the brake drum with rope in mtrs.(0.165m) D= Dia. Of Brake drum (0.30 m) d= Dia. Of rope (0.015 m) N= Speed in Rpm. 3) Input Power = wQH in KW Where, w= specific weight of water = 9.81 KN/m3 Q= Discharge in m3/sec. = K¥h Where, K=

R R R R R

;

a1 = 7.854 x 10-3 m2( pipe dia. 100mm) a2 = 2.752 x 10-3 m2 (throat dia. 59.16mm) h= (P1 ± P2) x 10 m. of water. H= Head in meters = (Suction head, hs + Delivery Head(or Turbine head) hd ) m. of water.

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1. Discharge vs efficiency 2. Speed vs Brake Power 3. Speed vs Efficiency

ccc 1. Never run the apparatus if power supply is less than 390 volts and above 420 volts. 2. To prevent clogging of moving parts, run pump at least once in a fortnight. 3. Always use clean water. 4. Drain the apparatus completely after experiment is over. 5. Always keep apparatus free from dust.