Download presentation

Presentation is loading. Please wait.

Published byNathan Campbell Modified over 3 years ago

1
Hydrodynamics of Pumps Christopher E. Brennen California Institute of Technology, Pasadena, California With many thanks to Allan Acosta, Dave Japikse, innumerable colleagues, a special group of students at Caltech, and a special debt to NASA Marshall, to Loren Gross, Otto Goetz and Henry Stinson.

2
Prediction of problems: Turbomachine Power proportional to L 5 3 = L 2 ( L) 3 Therefore, same power, same fluid, if L decreases then L must increase and since is prop. to ( L) -2 cavitation must increase Also…

3
Since fluid pressures prop. to ( L) 2 Then blade stresses prop. to ( L) 2 (L/T) 2 And therefore for the same power, same fluid, same geometry, blade stress is prop. to L -4/3

4
Lecture One: Introduction Specific Speed and Pump Design Non-cavitating performance Secondary flows incl. Prerotation

5
Geometric Notation:

9
Streamtube: Velocity Triangle:

10
Incidence Angle Deviation Angle

16
Reynolds Number effects:

17
Non-cavitating pump performance analysis

19
Using Bernoullis equation in rotating coordinates, a simple expression for the viscous losses (f), assuming simple geometry, zero deviation, and no preswirl, leads to a simple pump performance analysis:

21
And with only slightly more complex loss mechanisms (m D ):

23
Deviation from inviscid calculation:

24
Viscous losses in blade wakes (axial cascade):

25
Axial cascade losses:

26
Centrifugal cascade analysis:

27
Displacement component of inviscid flow:

28
Busemann slip factor for inviscid flow:

29
Viscous wakes in centrifugal pumps:

30
Three-dimensional analysis: A radial equilibrium calculation

35
Secondary Flows Some secondary flows : Within the blade passage At inlet – tip clearance flow and backflow for an unshrouded impeller Shrouded centrifugal pump Cutwater separation in volute

39
Prerotation Widespread misunderstanding Prerotation may be caused only by Backflow or Upstream Asymmetry

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google