Turbinas - Donado

7/29/2019 Turbinas - Donado

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HYDRAULIC TURBINE

BASIC HYDRAULICS


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ASSISTANT PROFESSOR

http://sites.unal.edu.co/a/bt.unal.edu.co/lddonadog

Leonardo David DONADO-GA


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CLASIFICATION

IMPULSE REACTION
http://www.youtube.com/watch?v=HzQPNpP55xQ&NR=1


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PELTON WHEELS

So called in honor ofLester A. Pelton (1829-1908)

Patent in 1880 on animproved with a splitter in

the middle. W.A. Doble brought out

the ellipsoidal buccket,basis of the modern forms
http://www.youtube.com/watch?v=4vGeUmbvcDk&feature=fvw


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KAPLAN TURBINES


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THE HYDRAULIC IMPULSE TURBIN

HORIZONTAL Single Nozzle

Single-overhu

Double-overh

VERTICAL SHA

Multiple Nozz


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SETTINGS

www.geppert.at


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HEAD ON IMPULSE TURBINE


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HEAD ON IMPULSE TURBINE

22 2 2

2 1 2 2

1

1

1 1 2 2 2 2

= + = + +

B B

v

p V A V v Vh k

g C A g g

Where:C

vis the coefficient of velocity of the nozzle

A2

is the cross sectional flow area of the jet

A1 is the cross sectional flow area of the pipe upstream of the nozzleV1

is the velocity of jetv2

is the velocity of water relative to bucket at exit from bucketV2

is the absolute velocity of water leaving the bucketh is the energy head delivered to the bucketsk is the bucket friction loss coefficient [0.2 0.6]


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NOZZLES

In order to maintain a constant

speed of rotation Size can vary with the position of

the needle

Shape of both nozzle tip andneedle should cause a minimumfriction loss and avoid cavitation

damage The main idea is having all

particles of water moving inparallel lines, with no spreadingout.

2=jet VP Q

energy.saving.nu/hydroenergy/


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EXAMPLE

A 6-in-diameter pipe (f = 0.020) of lengthdelivers from a reservoir with a water-surfaceof 500 ft to a nozzle at elevation 300 ft. Ththe nozzle is used to drive a small impulse tthe head loss through the nozzle can be exp0.04 of the kinetic energy of the jet, findiameter that will result in maximum powerNeglect the head loss at entrance to the pipereservoir. Evaluate the power in the jet.


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HOMEWORK

How is regulated the

speed in an impulseturbine?

How are constructed thewheels?

How is determined thewheel diameter?

Efficiency variation withsize and head


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ACTION OF THE JET

Bucket velocity, u

Abs

Jet v

Relative

Bucket velocity, v1


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ACTION OF THE JET


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TORQUE AND POWER FOR IDEAL C

v2V2

u

V2= u + v

2

v1

V1

u

V1= u + v1

2 1 2 = = V V V

( ) 2 = =uF Q V

2= = u

DT F QD

1 20 180 = =


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v2

V2

u

V2= u + v

2

v1

V1

u

V1= u + v

1

2

2

cos1

1

=

+ uF Q

k

2cos2 1

1

= +

h k

1 20 165 = =


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ACTUAL TORQUE AND POWER


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EXAMPLE

Find the torque and power transferredbuckets of an impulse wheel with 1=0, k= 0.44, =0.46, Cv=0.98, a jet diameterand a pitch diameter of 10 ft. Findhydraulic efficiency, and, expressedpercentage of the total head, find: the hebucket friction, the energy head lossdischarge, and the head loss in the nozzle.


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SPECIFIC SPEED

A turbine is to o

400 rpm under aof 1320 ft. If ain-diameter jetfind the specificthe machine

Cv=0.98, =0=0.85. Findrequired pitch dthe wheel.


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REACTION TURBINES

Francis

10 < Ns < 100

Radial-flow

Mixed-flow

Kaplan:

100 < Ns < 250

Axial-flow


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SPECIFIC SPEED

For a small power under high head a Peltwith its low specific speed is used torotative speed down to a suitable value, wlarge power under a low head a reactiowith its higher specific speed is used torotative speed to a suitable value.

A lot of possible combinations of N and P twith the fixed H.


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REACTION TURBINES


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REACTION TURBINES


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TUBE TURBINE

10 < h < 60Axial Flow


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SETTINGS


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DRAFT TUBES

Integral part of the

turbine and a desi Enable the turbine

above the tail watwithout losing any thereby

Reduce the head losubmerged discharthereby increase thavailable to the ru( ) 2 21 1 2

1

2 2

abs atmL

p p V Vz h

g g = + +


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DRAFT TUBES


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NET HEAD

22

2 2

CB BB

Vp Vh zg g

= + +

( ) ( )2 2

1 2 2

2 2

CV V V V h h k

g g

= +

O A ON A N S


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OPERATION AT DIFFERENT SP

For the inward-

Francis turbine

centrifugal acti

decreases the f

increasing whee

Francis: 0.7 <

Kaplan: 1.4

Turbinas - Donado

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