Kaplan Turbine Experiment 1m3z5k

TESTING OF KAPLAN TURBINE

OBJECTTIVE: To conduct an experiment on Kaplan Turbine.

INTRODUCTION: Turbines are the turbo machines transferring fluid energy into mechanical energy. Axial flow hydraulic turbine is named Kaplan turbine. Rotor blade settings of these turbines are adjustable. Axial flow fixed bladed turbine is Propeller turbine. The main parts of a Kaplan turbine are the rotor, inlet guide vanes and the turbine shaft. The rotor with the adjustable blades is used to transfer the fluid energy into the mechanical energy. The nozzle guide vanes are used to direct the flow onto the rotor and also regulate the power output of the turbine by adjusting the flow rate. The turbine shaft holds the servomechanisms adjusting the blade angle and connects the rotor to the generator. Kaplan turbines are especially adaptable to low total head change and high flow rate water sources.

EXPERIMENTAL SETUP: 1. TURBINE: A reaction with a fixed propeller Kaplan runner is mounted on the setup. It has adjustable nozzle guide vanes. 2. DYNAMOMETER: A friction dynamometer is coupled to the turbine rotor to measure the torque. There is a spring balance at the end of the friction belt and a carrier to hold the dead weights at the other end. The diameter of the friction drum is d=30.5cm. 3. TACHOMETER: it is a mechanical device to determine the rotational speed of the turbine in revolution per minute (rpm). 4. BOURDON INLET PRESSURE GAUGE: It is used for measuring inlet pressures in meters of water column within the range of 0-7.5 m H2O. 5. SURGE TANK: A surge tank with a sight tube to indicate the water level in the tank which is the outlet static head.

Fig: A simple working of Kaplan Turbine

MEASUREMENTS: 1) Set the nozzle guide vane angles to a specified degree by means of the lever. 2) Set the inlet static head of the turbine. 3) Measure the following values: a) The speed of the turbine in rpm (N) b) The dead weight in kg (W) c) The force on the spring balance in kg (F) d) The deflection of U-tube manometer in mm (∆P) e) Inlet static pressure of the turbine in m (Hi)

f) Outlet static pressure of the turbine in m (Ho)

CONSTRUCTION SPECIFICATIONS: a) Spiral Casing: Spiral casing is of close-grained cast iron with flanged inlet, designed for constant velocity water distribution.

b) Runner: Runner is of Gunmetal with four aerofoil blades, designed to the latest hydrodymanic principles. The runner blade pitch can be adjusted by suitable mechanism operating through the hollow shaft.

c) Guide Vane Mechanism: Consists of GM vanes cast integral with their spindles. By suitable external link mechanism these can be at different relative positions, and two external dummy guide vanes are provided to indicate the exact position of the actual guide vanes working inside the turbine, thus showing the relative as water ages through the guide mechanism for the different position of guide vanes.

d) Shaft: Shaft is of high carbon special steel EN-8 and hollow to accommodate the runner blad control mechanism.

e) Ball Bearings: Ball bearings are of heavy-duty type designed for long life. One double row deep grove rigid ball bearings to take care of radial loads and a thrust and self-weight of the rotor assembly are provided in the bearing bracket. A self-aligning type ball bearing is used in the bearing pedestal for trouble-free operation.

f) Draught Tube:

Draught tube is of mild steel fabricated construction. It is provided at the exit of the runner. g) Observation window: A transparent Perspex hollow cylinder window for observation of the flow age through the runner is provided in between the casing and the draught tube.

h) Brake arrangement: Brake arrangement consists of a machined and polished brake drum, pulleys, cooling water supply pipe, internal water scoop, discharge pipe, rope brake etc.

i) pedestal: It is of cast iron, rbust in construction and s the entire turbine assembly, with ports for the study of flow pattern around the runner through the observation window.

Fig: A simple construction of Kaplan Turbine

TECHNICAL SPECIFICATIONS: 1) Kaplan Turbine:

Rated Supply head : 5m Discharge: 6000 LPM Rated Speed: 1500 RPM Power output: 3.75 kW Brake Drum Diameter: 300mm Rope Diameter: 16mm

2) Guide vane: No. of guide vanes operating inside: 16

The turbine profile: Aerofoil Width: 65mm Depth: 76mm Adjustment: 20o (max)

3) Runner: No. of vanes: 4 Material: Gunmetal Width: 127mm Depth: 52mm Angle Adjustment: 15o max Hub outer dia: 200mm Hub inner dia: 110mm

PROCEDURE: Make sure before starting that the pipelines are free from foreign matter. Also note whether all the ts are watertight and leak proof. Fill up clear cold fresh water through vertical column up to the top level, so that supply pump, delivery piping, turbine, and sump are filled with water. The guide vanes in the turbine should be in the closed position while starting the pump. Then slowly open the butterfly valve to regulate the discharge and net supply head on the turbine in relation to the spear settings. Run the turbine at around 1500 rpm for sometime to check whether all the parts are working fine. The turbine is now gradually loaded and the readings are taken. To load the turbine standard dead weights are provided with the unit. Load the turbine gradually and do not load it suddenly. Load the turbine gradually and at the same time open the guide vanes to run the turbine at normal speed.

EXPERIMENT: Turbine shall first be tested at constant net supply head by varying the load, speed and fluid vane setting and the runner blade position. However the net supply head on the turbines may

be reduced and the turbine tested in which case the power developed by the turbine and the best efficiency speed is also reduced. The output power from the turbine is calculated from the readings taken in the brake and the speed pf the shaft. The input power supplied to the turbine is calculated from the net suppy head on the turbine and discharge through the turbine. Efficiency of the turbine being the ration between the output and input and can be determined from these two readings. The discharge is measured by the venturimeter and with the manometer fitted with scale. Supply head is measured with the help of the pressure gauge. After starting and running the turbine at normal speed for sometime, load the turbine and take readings.

Note the following: 1.

Net supply head

2.

Discharge

3.

Turbine shaft speed

4.

Brake weight

5.

Spring balance reading

For any particular setting if the guide vanes and runner blades, first run the turbine at light load and then gradually load it, by adding dead weights on the hanger. The net supply head on the turbine shall be maintained constant at the rated value, and by adjusting the gate valve fitted just before the turbine. IMPORTANT FORMULAE:

Where; •

N = turbine speed in RPM

•

T = torque in kgm i.e. T = W x Re

The value of the constant depends on the unit in which power is measured. The value of the constant for different units of power is given below:

1) Power in kilowatts = constant 6120 2) Power in metric H.P. = constant 4500 3) Power in British H.P. = constant 4560

Fig: Propeller of Kaplan turbine

OBSERVATION TABLE:

S.NO.

SHAFT SPEED (RPM)

MANOMETER READING P1 Kg/cm2

P2 Kg/cm2

∆P Kg/cm2

1 2 3

CALCULATIONS: 1. Net head of turbine

Where; Hi = Inlet total head of turbine Ho = Outlet total head of turbine

BRAKE WEIGHT (Kg)

SPRING WEIGHT (Kg)

NET BRAKE WEIGHT (Kg)

SUPPLY HEAD (m)

2. Discharge

Where; k = 0.0197; ∆h is in mm.

3. Power extracted from fluid

Where; ρ = density of water (1000 kg/m3) g = gravitational acceleration Q = discharge ∆H = net head of turbine

4. Brake power

Where; T = torque (=g.D.(W-F)) N = speed of shaft

5. Efficiency

Where; Psh = Brake power Ph = Power extracted from fluid

RESULT: S.NO.

MANOMETRIC HEAD ∆h (m)

DISCHARGE (m3/s)

IPNUT POWER (KW)

BRAKE POWER (KW)

EFFICIENCY Ƞ (%)

1 2 3

The average efficiency of the Kaplan Turbine is found out to be: Ƞ avg = _________%

PRECAUTION: 1. The turbine parts must be oiled properly. 2. Clean water should be filled in.

3. There should not be any foreign particle in the transmission line or in the turbine. 4. Proper guidelines should be followed while operating the turbine. 5. The machine should be handled carefully. 6. Overheating of rope brake should be avoided. 7. Turbine should not be loaded suddenly. 8. Turbine should be run at normal speed.