INSTRUCTIONAL MANUL
FRANCIS TURBINE
OBJECTIVE:
To study the operation of a Francis Turbine and determine the output power and efficiency of
Francis Turbine.
INTRODUCTION:
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.
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 centre and discharges out axially. It operates under medium heads and requires
medium quantity of water.
DESCRIPTION FRANCIS TURBINE TEST RIG(5 HP):
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 supported 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 head.
Spiral Casing: It is of close grained cast iron with integral legs.
Reaction Turbine
Runner: It is of gunmetal designed for efficient by a hand wheel through a link mechanism.
External dummy, guide vanes working inside the turbine.
Shaft: It is of steel accurately machined and provided with gunmetal sleeve at the stuffing box.
Ball Bearings: 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.
Draft Bend: It is provided at the exit of the runner with a transparent cylindrical window, for
observation of flows pass the runner. To the bend is connected a straight conical draft tube of
mild steel fabrication.
Brake arrangement: 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.
Observation Window: A transparent Perspex hollow cylinder window for observation of flow
passage, through the runner is provided in between the casing and draught tube.
UTILITIES REQUIRED:
I. Francis Turbine (Reaction Turbine)
i) Power output : 1HP
ii) Speed:………… rpm
iii) No. of guide vanes:
iv) Brake drum diameter: 300mm
v) Rope diameter: 15mm
II. Supply Pump set:
i) Power required : …….HP
ii) Type: Centrifugal
III. Flow Measuring Unit:
i) Diameter of Inlet: ………….mm
ii) Diameter of throat: ……. mm
iii) Venturi meter constant : K= 0.013 (Q = K √h) where h in meter of water
EXPERIMENTAL PROCEDURE:
Starting Procedure
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.
Closing Procedure:
1. When the experiment is over, first remove load on dynamometer.
2. Open the by-pass valve.
3. Close the ball valves provided on manometer.
4. Switch OFF pump with the help of starter.
5. Switch OFF main power supply.
TABULATION:
Sl.
No
SPEED
(RPM)
PRESSURE GAUGES
READINGS
INLET
THROAT
PRESSUR
PRESSURE
(P1) IN
(P2) IN
kg/cm2
kg/cm2
NET
(P1-P2)
VACUUM
HEAD
TURBINE
HEAD
APPLIED
WEIGHT
(W1) IN kg
SPRING
WEIGHT
(W2)IN kg
NET
WEIGHT
(W) IN kg
INPUT
POWER
OUTPUT
POWER
CALCULATION:
1) Efficiency =
𝑩𝒓𝒂𝒌𝒆 𝑷𝒐𝒘𝒆𝒓
𝑰𝒏𝒑𝒖𝒕 𝑷𝒐𝒘𝒆𝒓
𝒙 𝟏𝟎𝟎
%
𝟐. 𝝅. 𝑵 .𝑻
2) Brake Power = 𝟔𝟎 ×𝟏𝟎𝟎𝟎 𝑖𝑛 𝐾𝑊
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=
𝒂𝟏 .𝒂𝟐 . √𝟐.𝒈
√(𝒂𝟏 𝟐 − 𝒂𝟐 𝟐 )
;
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.
EFFICIENCY
GRAPHS:
1. Discharge vs efficiency
2. Speed vs Brake Power
3. Speed vs Efficiency
PRECAUTION AND MAINTENANCE INSTRUCTIONS
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.
CONCLUSION: