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Guide vanes in Francis turbines

Date post: 04-Jan-2017
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Guide vanes in Francis turbines
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  • Guide vanes in Francis turbines

  • El Cajon, HONDURAS

  • Revelstoke, CANADA

  • P = 169 MWH = 72 mQ = 265 m3/SD0 = 6,68 mD1e = 5,71mD1i = 2,35 mB0 = 1,4 mn = 112,5 rpm

    La Grande 3, Canada

  • La Grande 3, Canada

  • La Grande 3, Canada

  • Guide vane cascade, Francis

  • Guide Vane End Seals

    High efficiency Less erosion Less leakage in closed pos.

  • Guide vanes

    Main function:Adjust the turbine load

    The guide vanes consist of number of blades that can be adjustedin order to increase or reduce the flow rate through the turbine. The vanes are arranged between two parallel covers normal to the turbine shaft.

  • Pressure distribution and torqueLL

    DD

    Torque

    Arm

    LL

    DD

  • Guide vanes in closed position

    ZDl 0= lBHgF 00 =

    000 aFMTorque ==

  • Guide vanes in open positionTr

    ailin

    g ed

    ge

    Trai

    ling

    edge

    Contour of the guide vane

    Pressure distribution along the contour of the guide vane:

    =

    +

    +=

    g2c

    g2cHh

    lossesg2

    chH

    22

    2

    Pressure distribution can be found using Bernoullis equation:

  • Pressure distribution along the contour of the guide vane:

    Stagnation-Point at Leading Edge

    Small flow rateLarge flow rate

    Guide vane contour

    gc2

    2

  • Variation of the torque when the guide vane opening changes:

    ( )02 0m fQDM2C =

    =

    0

    3

    4

    1

    2

    Sin 0

  • c m1

    cm145s H

    Horsepowernn =

    0nsPowerplant0nsPowerplant

    38365Solbergfoss34198Nore II37346Gravfoss23113Grnsdal

    36,5308Fiskumfoss18104Rssga40,5308Fiskumfoss1378Mesna31,5269Iverland1372Hol I38,5264Oltesvik1269Nedre Vinstra27,5208Dynjafoss1266Skjrka

  • 38365Solbergfoss14

    34198Nore II7

    31,5269Iverland10

    38,5264Oltesvik9

    27,5208Dynjafoss8

    36,5308Fiskumfoss12

    40,5308Fiskumfoss11

    37346Gravfoss13

    0nsPowerplant

    23113Grnsdal6

    18104Rssga5

    1378Mesna4

    1372Hol I3

    1269Nedre Vinstra

    2

    1266Skjrka1

    The guide vane maximum angle 0 at full load

    NB: This is for Norwegian designed GE-turbines

    45s HHorsepowernn =

    Specific speed, ns

    Guide vane angle

  • The servos work

  • The servo has to:Take care of the torque from all guide vanesfor all guide vane angles

    The torque consist of:Hydraulic torqueFriction torque

  • Hydraulic torque

    20m

    QDC2M

    =

    ( )0m fC =The hydraulic torque can be found from a CFD-analysis

  • Friction torque

    ( )Z

    DBHd,fM ff

    =

    d

    ff (,)= empirical value = friction factor

    H = Head

  • Stroke

    Friction

    Closing

    Opening

    Hydraulic forces

    Fully

    ope

    n

    Opening

    High head Francis turbineMeasurements of the servos work

    Forc

    e in

    100

    0 kg

  • Horse shoe vortex damage

  • Cavitation damage

  • Sand erosion in the guide vanes

    Jhimruk Hydro Power Plant

  • Head coverHead cover

    k

    Bottom cover

    Guide vane shaft

    Head cover

  • Z

    Y

    1 2

    The deflection of the head cover

    H = 435, P = 25 MW

  • Reduction of clearance

  • Efficiency of repaired turbine

    [MW]

    H = 430 m

  • Design of the Guide Vane Inlet Angle

    The inlet angle can be calculated by assuming a free vortex from the flow coming from the spiral casing

    StayVaneinletStayVaneinletuGuideVaneinletGuideVaneinletu rCrC =

    BDQCGuideVaneinlet

    GuideVaneinletm = Dinlet Guide Vane

    rinlet Stay Vane

    B

  • Design of the Guide Vane Outlet Angle

    The outlet angle can be calculated by assuming a free vortex from the flow in the gap between the runner and the guide vanes

    110 rCrC uou =

    00 BDQCmo

    =

    D0

    r1

    B0

  • Design of the Guide VanesHow to choose the number of vanes

    The number of guide vanes has to be different from the number of runner vanes.

    Integerzz

    VanesRunner

    VanesGuide

  • Design of the Guide VanesHow to choose the number of vanes

    The number of guide vanes has to be different from the number of runner vanes.

    Integerzz

    VanesRunner

    VanesGuide

  • Design of the Guide VanesHow to choose the guide vane maximum

    angle 0 at full load

    ( )11344 2 ++=o

  • Design of the Guide VanesOverlapping of the guide vanes

  • Design of the Guide VanesNumber of guide vanes

    16

    18

    20

    22

    24

    26

    28

    30

    0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

    Speed Number

    Num

    ber o

    f Gui

    de V

    anes

  • Design of the Guide VanesDiameter of guide vane shaft

    1,0

    1,1

    1,2

    1,3

    1,4

    1,5

    1,6

    1,7

    0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

    Speed number

    Dia

    met

    er R

    atio

    D0/D

    1

    D1

    D2

    07,129,01

    0 +=DD

  • Statement of ProblemGivens Net head...201.5m

    Flow rate...2.35m3/sTurbine speed.1000rpm

    Work out Design of Runner, Guide vanes,Stay vanes, Spiral casing andDraft tube

    Compare Design output with Jhimruk turbines

    Calculations - based on hydraulic principles only,

    Thickness of runner blades - neglected,

    Designs of components - done for the best efficiency point,

    Other several assumptions - mentioned locally in calculations.

    Design Considerations

  • Design of Guide Vanes

    .

    1,0

    1,1

    1,2

    1,3

    1,4

    1,5

    1,6

    1,7

    0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6

    Speed numberD

    iam

    eter

    Rat

    io D

    0/D1

    D

    1

    D

    2

    07,129,01

    0 +=DD

    Diameter of guide vane axisD0 = D1 (0.29 +1.07)

    = Q

    602 n

    =

    gH2/ =

    66.1=

    gHQQ 2/=

    319.0=

    Chosen:Nos. of guide vanes z =20

    mD 011.10 =

    037.0=

    Q

    = Q

  • Design of Guide Vanes

    .

    Tangential and meridional velocities

    05.11

    )(CuC gvou = smC gvou /64.39)( =

    smC gvom /58.8)( =

    Assuming gap between runner and guide vanes5% of the runner inlet diameter.

    [ (( )

    =

    11

    )( )Cosz

    Qt

    DBC

    gvogvo

    gvom

    tan (gvo) = Cm(gvo)/Cu(gvo)(gvo) = 12.210

    Value of gvo in full guide vane open position is selected 180

  • Design of Guide Vanes

    .

    Velocities at outlet, axis and inlet of guide vanes(depending on varing values of and t)

    Outlet agvo=12.210 tgvo=5mmCm(gvo) = 8.582 m/secCu(gvo) = 39.65 m/secCgvo = 40.56 m/sec

    Axis agvc=28.040 tgvc=30mmCm(gvc) = 9.521m/secCu(gvc) = 17.87 m/secCgvc = 20.25 m/sec

    Inlet agci=340 tgvi=15mmCm(gvi) = 7.864 m/secCu(gvi) = 11.65 m/secCgvi = 14.06 m/sec

    Cm(gvi)=7.86 m/secCgvi=14.06 m/sec

    Cu(gvi)=11.65 m/secCgvc=20.25 m/secCm(gvc)=9.521 m/secCu(gvc)=17.87 m/sec

    Cgvo=40.56 m/sec

    Cm(gvo)=8.58 m/secCu(gvo)=39.65 m/sec

    L = 204

  • Design of Guide Vanes

    Guide vane at DesignPosition = 12.21

    Guide vane at closed position

    Guide vane at Max. openPosition = 18

    .

  • Guide vanesGuide vanesGuide vanesGuide vanesGuide vanesGuide vanes

    Runner inlet ( 0.870m)

    Guide vane outlet for design) ( 0.913m)

    ClosedPosition

    Max. Opening Position

  • R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanes

    R a d i a l v i e wrunner guide vanes and stay vanesR a d i a l v i e wrunner guide vanes and stay vanes

    Water from spiral casing

    Water particle


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