Centrifugal Pump Volute Design

[Ángel Martin]

From the Author's Engineering Collection - and Available on the ETSII4 Module (ETI4 on the CL library).

This program calculates the geometric dimensions of centrifugal pump Volutes with Circular, Rectangular or Trapezoidal sections - reflecting a given configuration and performance conditions of the pump, as follows:

- Nominal flow thru the impeller, QR
- Impeller outer diameter, D2
- impeller rotating speed in rpm
- Impeller outer width, b2
- impeller blade exit angle, beta2
- impellers’ Pfleiderer’s coefficient, mu
this can also be calculated as function of number of blades, ZR - and internal diameter, D1)
- The friction losses coefficient in the volute, lambda3 (should be zero for circular volutes)

- If a diffuser is installed, the outer diameter of the diffuser, D3
if it has blades, the fluid exit radial speed, V3u
without blades, the friction coefficient in the diffuser, lambda2

- For Circular section volutes, the volute width at the tongue, bc

- For trapezoidal volutes, the volute width at the tongue, bc - and the aperture angle, delta

Once these data are entered the program will prompt for the angle to calculate the outer radius of the volute. This can be repeated for many angles in a loop to further characterize the volute geometry along the interval [0, 360], i.e. from the tongue to the throat. All angles are entered in degrees, and a homogeneous unit system is to be used (SI recommended).

Program Details.

Data Entry requires functions PMTK and ARCLI from the AMC_OS/X Module.

The PPC root-finding “SLV” routine is used for each calculation of the results in rectangular and trapezoidal section volutes. It is included in the ETSII4 module as well. Routines “R”, “T”, “T0” are used to describe the equation to solve, depending on the diffuser type.

The routine “NT” (NewType) allows for different types of volutes (Rectangular, Trapezoidal, or circular), and different design parameters known.


Example.
Calculate the dimensions of the three volutes types (use delta = 15 for trapezoidal) for a centrifugal pump with impeller rotating at 1450 rpm, without a diffuser and with the following configuration:
Qr = 52 l/s
D2 = 350 mm
b2 = bc = 10 mm
beta2 = 30 deg
mu = 0.809
lambdac = 0.04

The solutions are given in the table below;

Code:

Angle (deg)     Rectangular     Trapezoidal     Circular (center)     Circular radius
-------------------------------------------------------------------------------------------------------------
  0 (tongue)    R=0.1750        R=0.1750        a=0.1750             r=0.0000
 90             R=0.3167        R=0.2230        a=0.1924             r=0.0174
180             R=0.8965        R=0.2555        a=0.2000             r=0.0250
270                             R=0.2843        a=0.2060             r=0.0310
360 (throat)                    R=0.3115        a=0.2111             r=0.0361

[Dieter]

(11-02-2016 08:12 AM)Ángel Martin Wrote:  This program calculates the geometric dimensions of centrifugal pump Volutes with Circular, Rectangular or Trapezoidal sections

Please excuse me if this is a very dumb question, but... where is the program?

(11-02-2016 08:12 AM)Ángel Martin Wrote:  The solutions are given in the table below;

This will actually show up as a formatted table if you use a fixed-width font and an external editor. It will not work with hpmuseum's message editor and "visual formatting", especially not with a mixture of tabs and spaces.

Code:

Angle (deg)     Rectangular     Trapezoidal     Circular (center)     Circular radius
  0 (tongue)    R=0.1750        R=0.1750        a=0.1750             r=0.0000
 90             R=0.3167        R=0.2230        a=0.1924             r=0.0174
180             R=0.8965        R=0.2555        a=0.2000             r=0.0250
270                             R=0.2843        a=0.2060             r=0.0310
360 (throat)                    R=0.3115        a=0.2111             r=0.0361

I hope this is what you wanted to show, but I'm not sure since there are some characters that cannot be displayed.

Dieter

[rprosperi]

(11-02-2016 08:44 PM)Dieter Wrote:  Please excuse me if this is a very dumb question, but... where is the program?

I very nearly added the same comment, but certain that Angel would not simply forget, I re-read the post and there you'll find at the top it says "Available on the ETSII4 Module (ETI4 on the CL library)."

[Ángel Martin]

(11-02-2016 08:44 PM)Dieter Wrote:  This will actually show up as a formatted table if you use a fixed-width font and an external editor. It will not work with hpmuseum's message editor and "visual formatting", especially not with a mixture of tabs and spaces.

I hope this is what you wanted to show, but I'm not sure since there are some characters that cannot be displayed.

Thank you, that's exactly what I tried to show - this business with the fixed pitch font always trips me up/

As you see there are two omissions for rectangular volutes - the routine didn't converge to a sensible value. I tried with SOLVE instead of "SV" and the same issue showed up. The formulas appear to be ok, so I'm thinking the model may have some limitations for rectangular cases wide exit blade angles.

[Ángel Martin]

(11-02-2016 11:06 PM)rprosperi Wrote:  

(11-02-2016 08:44 PM)Dieter Wrote:  Please excuse me if this is a very dumb question, but... where is the program?

I very nearly added the same comment, but certain that Angel would not simply forget, I re-read the post and there you'll find at the top it says "Available on the ETSII4 Module (ETI4 on the CL library)."

Yes sorry if it wasn't clear enough - thing is I didn't feel like retyping the 400+ program steps... although I should have because I found two typos in the original code. An updated ROM was sent to Monte, and it's also attached here.

BTW I intend to follow up with the documentation for some of the other programs included in this collection, but it'll take a while. Not that simple to figure out some things after 30 years!

[SlideRule]

ALL

Centrifugal pumps: design & application 2e
Val S. Lobanoff, Robert R. Ross
Copyright© 1985, 1992 by Butterworth-Heinemann

Centrifugal Pumps 3e
Johann Friedrich Gülich
ISBN 978-3-642-40113-8
ISBN 978-3-642-40114-5 (eBook)
DOI 10.1007/978-3-642-40114-5
Springer Heidelberg Dordrecht London New York
Library of Congress Control Number: 2013951850
© Springer-Verlag Berlin Heidelberg 2008, 2010, 2014

Kreiselpumpen
Handbuch für Entwicklung, Anlagenplanung und Betrieb
4., aktualisierte und erweiterte Auflage
ISBN 978-3-642-40031-5
ISBN 978-3-642-40032-2 (eBook)
DOI 10.1007/978-3-642-40032-2
© Springer-Verlag Berlin Heidelberg 1999, 2004, 2010, 2013

are ALL excellent reference material for this topic.

BEST!
SlideRule

[Ángel Martin]

(11-03-2016 09:49 PM)SlideRule Wrote:  ... ALL excellent reference material for this topic.
SlideRule

Sure there's got to be good reference materials nowadays, thanks for the suggestion. Back in the day we used two books, one by a French author (Marcel Sedille) - "Turbo-Machines, Hydrauliques et Thermiques"; and the Spanish bible-reference "Turbomáquinas Hidráulicas", by Claudio Mataix.

The funny thing was the French book was already out of print even then, but the teacher insisted it was "the one" - probably because he used it to study the subject himself. Needless to say that not having the text widely available didn't make it easier on the students, which I always suspected was part of the same plot ;-)