`
`UTC-2017.001
`
`GE V. UTC
`
`Trial IPR2016-01301
`
`UTC-2017.001
`
`GE v. UTC
`Trial IPR2016-01301
`
`

`

`This book is printed on acid—free paper.®
`
`Copyright © 2008 by John Wiley & Sons, Inc. All rights reserved.
`
`Published by John Wiley & Sons. Inc., Hoboken. New Jersey
`
`Published simultaneously in Canada.
`
`Wiley Bicentennial Logo: Richard .I. Pacifico
`
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`
`library of Congress Cataloging-in-Pubfr‘carion Data:
`
`Peng. William W,
`Fundamentals of tutbomachinery f by William W. Peng.
`p. cm.
`Includes bibliographical references and index.
`ISBN 978—0-470-12422—2 (cloth)
`1. Turbomachines.
`I. Title.
`T1267.P43 2008
`621.406—dc22
`
`2007013502
`
`Printed in the United States of America
`
`10987654321
`
`UTC-2017.002
`
`UTC-2017.002
`
`

`

`66
`
`Centrifugal Pumps
`
`Plot the complete performance curves including the efficiency with a spread sheet (such
`as Excel). Also predict this pump’s performance for N = 1850 rpm.
`
`SOLUTION The relevant formulas are given as
`
`
`pQgH _ 62.4 X 0.00223QH ‘
`”= P..-
`550 Ps
`
`Q2=
`
`
`QiNz
`N;
`
`,H
`
`2
`
`Note: H and PI at Q = 0 are obtained with extrapolation
`
`
`
`QI (gpm)
`0
`
`H, 1ft)
`205
`
`PA.1 (hp)
`28
`
`nl (91;)
`0
`
`Q2 (gprn)
`0
`
`H310)
`384.99
`
`P_..2(hp)
`72.044
`
`n2 (91¢)
`0
`
`285
`
`435
`
`540
`
`785
`
`920
`
`200
`
`195
`
`190
`
`136
`
`172
`
`31
`
`36
`
`42
`
`44
`
`49
`
`46.5194
`
`59.6131
`
`61.8043
`
`83.9558
`
`81.7035
`
`390.45
`
`595.95
`
`739.8
`
`1075.45
`
`1260.4
`
`375.6
`
`366.21
`
`356.82
`
`349.303
`
`79.763
`
`92.628
`
`108.066
`
`113.212
`
`323.016
`
`126.077
`
`46.5168
`
`59.6099
`
`61.8009
`
`83.9512
`
`81.699]
`
`1275
`
`130
`
`58‘
`
`72.3013
`
`1746.75
`
`244.14
`
`149.234
`
`72.2974
`
`r.
`e
`a»
`
`n:
`
`II:
`
`4.4 CAVITATION
`
`
`
`N|=1350rpni
`
`
`
`N2: ISSOrpm
`n. 500
`a: —
`*- 4‘” m—
`
`a.“ 200
`
`
`
`3:
`
`0
`
`0
`
`1000
`Q (sum)
`
`2000
`
`Cavitation is a phenomenon which may occur in all hydraulic machines and systems.
`When the local pressure reaches a certain low value close to the vapor pressure corre-
`sponding to the fluid temperature, part of the fluid will vaporize and cause a change
`of flow pattern. In a centrifugal pump. this happens in the vicinity of the impeller
`inlet. The occurrence of cavitation causes noise, vibration, and deterioration of per-
`formance, as shown in Figure 4.10. In the long run.
`it will also damage the pump
`components, because of the impinging forces resulting from vapor bubbles collapsing
`at the higher pressure regions in the flow passage. This is called cavitation erosion.
`
`UTC-2017.003
`
`UTC-2017.003
`
`

`

`4.4 Cavitation
`
`cos 2745-2
`
`67
`
`EGOULDS PUMPS CENTRIFUGAL JUMP CHARACTERISTICS
`
`
`
`
`
`RPM 3560
`0100003700
`Size: 1.5X3‘9Nv MSX
`
`Pattern: 55112468026
`
`Area: 8.2 In3
`E
`Prelerrad Opalannq Heqi0_n-. 70 lo 120 ‘20 0! BE;‘
`
`130
`
`160
`
`5ft
`
`l—
`
`l
`43
`
`0
`
`4
`
`an
`
`L
`
`“
`
`Bit
`—l
`l—
`EA'T/ /
`1n
`
`25ft
`
`10ft
`
`5
`
`15‘
`
`~ 140
`'3
`:.
`|~120$
`2
`-
`100 g
`—— "
`
`x
`
`-
`
`5
`
`amp
`
`150
`
`9
`
`m
`
`mm:
`
`——i
`
`|____
`
`— 00
`
`_‘1- 60
`
`jw
`
`r 20
`
`600
`550
`
`500
`
`450
`E
`"
`§4°° 0.2m
`‘ 350
`‘3
`" 300
`
`.
`Bln
`
`250
`200 ?in
`Bin
`
`100
`
`50
`
`
`
`0
`
`.
`1—-
`.
`w—
`.
`u
`0
`40
`30
`120
`150
`200
`240
`280
`0
`10
`20
`30
`40
`00
`Capacity
`(5}
`
`50
`
`320
`
`—1
`?0
`
`gpm
`m3mr
`
`0
`
`CAPACITY— 01%
`so 00100
`200
`-
`'
`-
`
`-
`
`400
`--
`
`10
`
`-
`
`20
`
`r
`
`40
`'
`x
`
`
`
`1200
`1
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`__._
`
`
`
`
`
`201
`-
`
`10.
`10
`
`
`
`
`
`3
`E
`m
`E
`I
`2
`Lu
`f
`20 d:
`I—
`o
`l-
`
`10
`
`_
`
`.-
`
`=
`m E
`
`.
`.
`nun...
`_
`h
`
`H.
`0...
`..
`_.
`' ;, .. r; _y
`.
`__
`
`
`
`
`-
`111149104”
`..
`.00.
`..
`
`
`
`.
`-I- "-
`'- _.__
`..-
`-'
`'
`F
`I IIIM§ha-fl-é_.__
`H -millil‘ ‘Ei’lfiflifllllF
`IL 200 —I_——-__.
`I
`_.__
`__._a
`I
`y
`I
`r; “M :
`..;-:
`1
`1
`._
`~11" 1 *w‘ egn.’1_‘
`I
`n
`.
`‘ "
`‘
`5
`n
`V
`-
`’
`r I»
`'
`‘—
`I 1
`"l—--
`l—IA—“lgld’ E
`I
`-
`2' g'
`.. “a”? H"
`" -——=*'-
`‘
`
`5 70 Mug—r4 -.
`9-
`-
`.____l,_
`so .__
`I_
`..
`--~
`._
`.
`_
`
`50
`-
`.
`40 .
`30?
`
`.
`.5
`
`‘
`
`_+
`
`
`
`.
`
`.= .
`.
`
`-
`
`
`
`
`
`
`
`
`
`
`__ _._____
`._______ .
`.|_ . .___..
`._____. l.. ...I._l_._ __..
`20
`30
`40500070 90
`0000001000
`200 300 400
`2000 30004000 0000 10000
`CAPACITY— GALLONS PER MINUTE
`{D}
`
`__
`
`I
`
`C3560RPM
`
`C 1780 RPM
`
`(a) Performance curves of pump (size 1.5 x 3-9N) with impeller trimmed,
`Figure 4.7
`(1?) Composite petfonnance chart of different sizes of a pump model. (Courtesy of Goulds
`Pumps, ITT Corp. Seneca Falls. NY.)
`
`
`
`UTC-2017.004
`
`UTC-2017.004
`
`

`

`
`
`
`
`
`
`
`
`
`
`_|
`
`
`
`68
`
`200
`130
`E
`o 1 60
`c
`~0— 140
`E
`g 120
`in.
`g 100
`80
`
`I
`
`Centrifugal Pumps
`
`
`_
`i
`_ 250
`
`
`1 “a =
`900 Double suclion
`159ng Double suction
`m
`3
`fi
`2200
`E
`fi
`5 200
`4
`3000
`o
`4000
`5700 Single suction
`E
`g
`5?00 Single suction
`9200
`9200
`a:
`
`S 150
`8
`$100
`o
`3:?
`0
`o 5
`ix
`9
`m
`
`
`
`—|
`
`600
`
`25
`
`100
`r5
`50
`Capacity. percent or normai
`
`125
`
`1'50
`
`0
`
`25
`
`10°
`75
`59
`Capacrty. percent of normal
`
`‘25
`
`‘50
`
`0
`
`(:3) Brake horsepower vs. capacity
`(3) Head vs. capacity
`Figure 4.8 Effect of specific speed (impeller type) on pump performance curve shapes. (Reprinted by permission
`from Stepanoff. AJ. Centrifugal and Axin Flow Pumps, 2nd ed., John Wiley & Sons. New York, [957.)
`
`
`
`Casing
`
`
`
`Figure 4.9
`
`Flow recirculation at impeller inlet and outlet. for partial through flow rate.
`
`In some high—quality pumps, an inducer such as shown in Figure 4.1110 is installed
`upstream of the impeller to improve the cavitation performance.
`In order to prevent the occurrence of cavitation, a certain minimum pressure must
`be imposed at
`the pump inlet. A parameter called the NPSP (net positive suction
`pressure) or NPSH (net positive suction head = NPSprgJ is used to designate this
`minimum inlet pressure. It
`is defined as NPSP : pm h p1,, where pm is the total
`pressure at the pump suction flange and p... is the vapor pressure corresponding to the
`pumped fluid temperature, which can be obtained from steam tables in the case of
`
`UTC-2017.005
`
`UTC-2017.005
`
`

`

`4.4 Cavitation
`
`69
`
`Without
`cavitation
`
`liead.}i
`
`was
`
`
`
`/\\
`
`cavnanon
`
`
`Howram.Q
`
`Figure 4.10
`
`Performance deterioration due to cavitation.
`
`
`
`lnducers to improve cavitation performance. (Courtesy
`Figure 4.11
`of lngersoll—Rand Company. Phillipsburg. NJ.)
`
`water. For each pump, the required NPSP also varies with respect to the flow rate, as
`shown in Figure 4.70:. It is called required NPSP or NPSPR. Other parameters are also
`used in industry, such as the Thomas parameter or : NPSHI‘H‘ where H is the pump
`discharge head, the cavitation parameter r = NPSP/pU '2 or the suction specific speed
`S = NQ0'5l(NPSH)U'75 in the dimension of rpm{gpm}0'5i’ft0'75. The values of these
`parameters for each pump have to be determined from laboratory tests or empirical
`correlations. The onset of cavitation always takes place at the impeller inlet tip. where
`the relative flow velocity is maximum. but the detailed flow pattern is difficult to
`determine, unless CFD software is used.
`
`A typical cavitation test result is shown in Figure 4.12. Detailed discussion on
`the test facility and procedure will be given in a later section. The required NPSP is
`usually set at a 3% drop in efficiency. The general range of suction specific speeds
`with the dimension indicated above for the properly designed pumps is estimated by
`G. F. Wislicenus11 as follows:
`
`Single—suction pumps with overhung impeller
`Single—stage pumps with shaft running through impeller inlet
`Single-suction high—pressure multistage pumps
`
`7500 < S «c 10000
`6500 < S <
`9000
`5500 < S <
`T500
`
`UTC-2017.006
`
`UTC-2017.006
`
`

`

`70 Centrifugal Pumps
`
`N: const.
`
`“X”.
`DrainorI)HIH,
`
`NPSH 0W1
`
`Figure 4.12 Typical cavitation test result.
`
`The lower value of suction specific speed means poor cavitation performance, since
`it requires higher NPSH.
`
`In selecting a pump for a hydraulic system, the pressure at the pump inlet should be
`such that its corresponding available NPSP be greater than the required NPSP specified
`by the pump manufacturer, that is, NPSPA > NPSPR. The available NPSP or NPSPA
`can be calculated according to the system condition. Two examples are illustrated in
`Figure 4.13. If the pump is required to pump water from an open tank, the available
`NPSP at the pump inlet is
`
`NPSPA = P01 - p..- : p] + 501’? — p1. 2 pa i- ng — Pf — p...
`
`where the minus sign is for the lift when the pump centerline is above the tank water
`level and the plus sign is for the head when the pump centerline is below the tank
`water level. Whiie pf is the pressure drop due to friction in the suction pipe, pa is the
`atmospheric pressure, which will be lower at higher altitude. Or pa = p,
`is the tank
`pressure for an enclosed tank.
`to have a lower required
`To improve a pump‘s cavitation performance, that is,
`NPSP, it is important to streamline the flow at the suction area. For the high-specific-
`speed pumps (mixed- or axial-flow impeller), a higher number of vanes will help. For
`the low-specific~speed pumps (radial—flow impeller), removal of some vanes at the lead-
`ing edge to increase flow passage area can generally improve cavitation performance.
`Also, to reduce the noise and vibration due to cavitation, a small amount of air can be
`
`l
`
`introduced to reduce the collapsing forces of vapor bubbles.
`
`Example 4.3
`
`Plot the performance curves of the pump with 8—in.
`typical form shown in Figure 4.6%).
`
`impeller in Figure 4.70:
`
`in the
`
`
`
`(a) Lift
`
`(a) Head
`
`Figure 4.13 Available NPSP with system lift and head.
`
`UTC-2017.007
`
`UTC-2017.007
`
`

`

`4.4 Cavitation
`
`71
`
`The expression P5 = pQgHI‘n = 62.4 x 0.00223QH1’1} is used to
`SOLUTION
`calculate the shaft power for all finite flow rate conditions. For the shutoff condition,
`since I} is zero, P5 has to be extrapolated. Also 0.1H is plotted, instead of H in the
`same chart. because its order of magnitude is higher than the others.
`
`
`
` Q (gpm) 1010 (0) eff (96) NPSHR (m Ps (hp)
`
`
`
`
`
`
`
`40
`30
`120
`
`27
`26.5
`25.5
`
`30
`42.5
`52
`
`5
`55
`6.1
`
`9.103
`12.62024
`14.88808
`
`17.13439
`7.5
`56.7
`24
`160
`19.08596
`11.5
`57
`21.5
`200
`
`220 20.42569 20 54.5 16
`
`
`
`
`Pump performance curves
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`o HMO (ft)
`- eff (%)
`n NPSHR (ft)
`0 PS (hp)
`
`
`
`HHOflI).eff(%).NPSHRm).Ps(hp}
`
`
`
`
`
`0
`
`SU
`
`150
`100
`Flow rate Q {gpml
`
`200
`
`250
`
`Note: The efficiency and NPSHR are read from the constant contours with inter—
`polation and P5 is calculated with the above equation.
`
`Example 4.4
`
`The pump with impeller trimmed to 8-in. in Figure 4.7a is
`selected for the system shown. Read the head, flow rate,
`and NPSHR at the hop. Determine the minimum height Z
`required if the tank pressure is 20 psia, friction loss in the
`suction line is 1.5 psi at 50 gpm. and water temperature is
`150°F.
`
`
`
`UTC-2017.008
`
`UTC-2017.008
`
`

`

`72
`
`Centrifugal Pumps
`
`SOLUTION From Figure 4.70. H = 235 ft, Q = 170 gpm at b.e.p. of 57.5%. The
`corresponding NPSHR is 8.7 ft. From the steam table we have 3)., = 3.73 psia at T =
`150°F and NPSPA = p, —- p; + ng — pr 3 NPSPR. So we have
`9
`*
`pg
`[0
`X (50
`62.4
`144
`170 "
`p! _ pf _ .01:
`Z>NPSHR—-————————=8.7— 2 —1.5 x —3.73 ——,
`
`orZ 3 8.7 + 2.5 = 11.2ft.
`
`4.5 PERFORMANCE MODIFICATIONS
`
`toward reduced efficiency, head, and capacity.
`
`4.5.] Effects of Viscosity
`
`increases.
`
`UTC-2017.009
`
`UTC-2017.009
`
`

`

`SOLUTION The specific speeds for all three options are calculated as follows:
`
`References
`
`105
`
`_ 3600 x 5000‘5
`_
`0.5
`.
`_ 995 rpm x gpm /f
`N“, _
`350035
`4320 X 5000‘5
`167
`4
`N
`600 (mm)
`N ,
`3500,75
`,=__———:119.
`“=3
`From Figures 4.20 and 4.36. we obtain 11., = 0.75, Dm = 1.7. m, = 0.78. D53, 2 1.4, at =
`0.80, D... = 1.1, and the diameters D, = D_.,.Q°-5tH02-‘ = 1.7(5000-5t3500-25} = 8.8 in..
`D5 = 7.2 in., and Dc 2 6.8 in. The output hydraulic power can be calculated as
`
`=
`
`3.
`
`0.?5
`
`
`500‘15
`
`Pt = ngn = 500 x 0.00223 x 62.4 x 350 : 24,352ft-lbf/s = 44.3 hp = 33 kW.
`
`i
`
`Hence the electrical power required P9 = P;.l(npump >< rim, x ammo.) can be calculated
`for the three options as
`
`P— 33 —489kw
`“‘0.75x0.9‘
`‘
`
`‘
`
`-495kW
`3’3
`P—
`”_0.7sx0.95x0.9_‘
`33
`P..=———-=45. w.
`0.80x0.9
`8k
`
`‘
`
`REFERENCES
`
`l. Karassik. I. .|.. Krutzsch, W. C., Fraser. W. H., and Messina. J. P. (Ed). Pump Handbook.
`McGraw-Hill. New York. 1976.
`2. Stepanoff. A. J.. Centrfugal arid Axial Flow Pumps. John Wiley & Sons, New York,
`1957'.
`3. Hydraulic Institute. Hydraulic lnstitute Centrifugal Pumps Tests—2000. Hydraulic Institute,
`Parsippany. NJ.
`4. Hydraulic Institute. Hydraulic institute Vertical Pump Tests—2000. Hydraulic Institute. Par—
`sippany. NJ.
`5. Peng. W. W. and Jenkins, P. 15., “Hydraulic Analysis on Component Losses of Centrifugal
`Pumps." Symposium Proceeding of Perfomiance Characteristics of Hydraulic Turbines and
`Pumps, pp. 121-125, ASME Annual Meeting, Boston. MA. Dec. 1983.
`6. Goulds Pumps, Industrial Products Groups. Goulds Pump Manual GPM5. Goulds Pumps,
`IT'T Corp.. Seneca Falls, New York. 1983.
`"i. Fraser. W. H. “Recirculation in Centrifugal Pumps.” Proceeding of IO" Annual Turbo-
`machinery Symposium. pp. 95—100, Dec. 1981. Texas A&M University, College Stat-
`ion, TX.
`.I. “Inlet Recirculation in Centrifugal Pumps," Symposium Proceeding of Per-
`8. Tuzon. J.
`fonnance Characteristics of Hydraulic Turbines and Pumps, pp. 195—200. ASME Annual
`Meeting, Boston. MA. Dec. 1983.
`9. Alpan. K. and Peng W. W., "Suction Reverse Flow in an Axial-Flow Pump," J. Fluids
`Eng. ASME Trans. Vol. ll3. N0. 1. pp. 90—97. Mar. 1991.
`
`UTC-2017.010
`
`UTC-2017.010
`
`

`

`106
`
`Centrifugal Pumps
`
`10.
`
`ll.
`12.
`
`l3.
`
`14.
`
`15.
`
`l6.
`
`17.
`
`18.
`
`19.
`
`20.
`
`ingcrsoil-Rond's High Speed Pump: Your Logical Choice.
`Ingersoll—Rand Pumps,
`Ingersoll—Rand Company. Phillipsburg, NJ, 1983.
`Wislicenus, G. P., Fiuia' Mechanics of Turbomocninerv, McGrawvHill, New York, 1947.
`Sheth, K. K., Morrison, G. L. and Peng, W. W., “Slip Factors of Centrifugal Slurry Pumps,"
`J. Fluids Eng. ASME Trans, Vol. 109, pp. 313-318, Sept. 1987.
`Peng, W. W.. "Nonequilibrium and Dissolved Gas Effects on Cavitation in Centrifugal
`Pumps," Proceeding of Cavitation and Polyphase Flow Forum, pp. 46—48, ASME Fluids
`Engineering Meeting. June 1983.
`Church, A. H., Centrifiigol Pumps and Blowers, Robert E. Krieger Publishing, Huntington,
`NY, 1972.
`Hydraulic Institute, Hydrouiic Institute Engineering Data Book, Hydraulic Institute, Parsip~
`pany, NJ, 1979.
`American Petroleum Institute, Centrifitgoi Pumps for Petroleum, Heavy Duty Chemicoi and
`Gas industrv Services, AP! Standard 610. 8’” Ed, American Petroleum Institute, Washington,
`DC, 1995.
`Neerkcn, R. F., “Selecting the Right Pump,” in Fluid Movers. Pumps, Compressor. Fons
`and Biowers, J. Matley and the staff of Chemical Week Associates (Eds), McGraw—Hill,
`New York, 1979, pp. 122—133.
`Peabody Floway, Inc., Turbine Data Handbook. i“ coi, Peabody Floway, Inc'., Fresno, CA,
`1987.
`Schivley, G. P. and Dussourd, J. L., “Analytical and Experimental Study of a Vortex Pump,“
`J. Basic Eng. ASME Trans. pp. 889—900, Dec. 1970.
`Balje. O. E., Turbomocht’nes. John Wiley & Sons, New York, 1981.
`
`PROBLEMS
`
`4.1
`
`Test results on a single-stage, single—suction mixed—flow water pump operating at 575 rpm
`are given as follows:
`
`7600
`7000
`5000 6000
`4000
`3000
`2000
`1000
`0
`Flow rate (gpm)
`16
`19.2
`27
`23.5
`30
`32.5
`35.0
`37.2
`39.5
`Head (ft)
`81
`86
`84
`88
`75.5
`65.6
`50.0
`27.6
`0
`Efficiency (“/20
`_______________———————-
`
`(a) Plot curves for these values and the brake horsepower curve.
`{13) On the same sheet. draw the brake horsepower curve when the liquid pumped has a specific
`gravity of 0.9 but otherwise is the same as water.
`
`4.2
`A centrifugal pump whose performance curves are shown in Figure 47.1 is used to pump
`water of 150°F from a tank as shown. If an impeller trimmed to 8—in.
`is used, determine the
`flow rate and the motor power input at the best efficiency point and the minimum tank pressure
`required to avoid cavitation at the pump inlet (friction loss in the suction pipe is 0.8 ft).
`
`UTC-2017.011
`
`UTC-2017.011
`
`