Using CFD in the analysis of Impulse turbines with a focus ... · PDF fileUsing CFD in the analysis of Impulse turbines with a focus on the high ... SPH and commercial CFD package

Speaker Name: Shaun Benzon

Position: PhD Student (Lancaster University)

Company: Gilkes

Country: England, UK

Using CFD in the analysis of Impulse turbines with a

focus on the high capacity Turgo

• Introduction

• CFD Methodologies

Lagrangian Methods

Eulerian Methods

• The Turgo Turbine

• CFD analysis of the Turgo Turbine

Overview

• CFD covers middle ground between physical testing and

“on paper” analysis

• CFD applies to many branches of engineering

o Energy

o Automotive

o Aviation

o Naval

o Etc

• Must be coupled with understanding of the underlying

physics

Introduction

Finite control

volume fixed

in space

Finite

control

volume

moving with

the flow

(fixed

mass)

Infinitesimally

small

element

fixed in

space

Infinitesimally

small

element

moving

with the flow

(fixed mass)

Eulerian methods Lagrangian Methods

CFD Methodologies

Lagrangian Methods

• Mesh-less Lagrangian methods- particles moving with

flow

• SPH- Smooth Particle Hydrodynamics most popular [1]

• Originally designed for measuring astrophysical

phenomena in the 1970’s [2]. Its application to

engineering was discovered in the 1990’s-2000’s and is

currently being used to simulate a variety of highly

distorting fluids and solids [3].

• The SPH European Interest Community (SPHERIC)

was developed in 2005 to facilitate the spread of SPH

methods

Lagrangian Methods

SPH Methods for flow predictions at a Turgo

Comparative study by P. Koukouvinis et al. in 2011 between standard

SPH and commercial CFD package (ANSYS® Fluent®) [4].

Showed good average however

SPH was less stable with scatter.

Only measures torque on inside

surface of blades.

Eulerian Methods

• Solve governing equations at fixed locations in domain.

• Requires fine mesh in areas of high gradients can result

in high computational cost

• Shown good agreement with experimental results for

Pelton turbines [5, 6] using homogeneous multiphase

models with k-ω SST turbulence models [7]

• Can easily measure the torque on either side of the

runner blades

Eulerian Methods

Numerical Prediction of Pelton Efficiency

Study carried out by D. Jošt, P. Mežnar and A. Lipej in 2010

comparing CFD to experimental results for a Pelton using ANSYS®

CFX-12.1® with k-ω SST turbulence model and free surface flow

using two-phase homogeneous modelling [7].

The Turgo Turbine

The Turgo impulse turbine was invented by Eric

Crewdson, Managing Director of Gilkes, in 1919

and a patent was awarded in 1920.

A paper was presented in 1922 at the Institution of

Civil Engineers: Design and Performance of a New

Impulse Water-Turbine (Crewdson, 1922) [8,9].

Drawing of the 1920 Crewdson Turgo design showing the inlet plane

and cut section with the jet trace on the inlet wheel plane shaded [9]

Elevation and plan view showing the 1920

Crewdson design of the Turgo machine [9]

The Turgo Turbine

A similar turbine of the same capacity was later tested by Dr A. H. Gibson

of Manchester University showing a maximum efficiency of 83.5% under a

head of 200 feet, producing 106HP, at 640rpm (Crewdson, 1922) [9].

The 150HP (at full

load) turbine used

in the initial tests

was tested using a

65kW continuous

current compound-

wound interpole

generator, set up for

220V at 725-

750rpm [9].

The Turgo Turbine

PERFORMANCE ENVELOPE [10]

Head Range: up to 300m [11]

Power Output: up to 10MW

The Turgo Turbine

DESIGN LAYOUT [10]

The Turgo Turbine

The Turgo impulse turbine was developed to provide a simple impulse type

machine with a higher specific speed than a Pelton by inclining the jet to the

runner face [8, 10].

The first Turgo turbine was installed in 1919. Since then Gilkes have

supplied over 900 Turgo turbines producing a total of 300 MW to over 80

countries. Many of the original units are still in operation today [8, 10].

CFD analysis of the Turgo Turbine

Using Eulerian Method

1. Mesh Independence Study

2. Design Optimisation

CFD analysis of the Turgo Turbine

Mesh Independence Study

Mesh sizing for 2 bladed mesh study- 2.67M elements

CFD analysis of the Turgo Turbine

Mesh Independence Study

CFD analysis of the Turgo Turbine

Design Optimisation

CFD analysis of the Turgo Turbine

Design Modification

Blade geometry is split into a series

of control curves which can be

used to adjust the shape of the

runner.

The changes can be based on

analysis from flow visualisation or

using a systematic analysis such as

a Design of Experiments study.

CFD analysis of the Turgo Turbine

Mesh Generation

Inflation layers wrapping around the

trailing edge with the maximum prism

angle set to 180deg

Mesh sizing and quality is very important

in order to capture the flow correctly.

CFD analysis of the Turgo Turbine

Pre-processing

• Solver settings e.g. timestep

• Turbulence model e.g. k-ω SST

• Multiphase model e.g. Homogeneous

• Fluid pairing i.e. surface tension

• Interphase transfer e.g. Free-surface

• Boundary conditions- e.g. wall conditions

CFD analysis of the Turgo Turbine

Post-processing

Pressure profiles Velocity profiles

CFD analysis of the Turgo Turbine

Post-processing

Inlet

view

Outlet

view

1. Marongiu, J., C., Leboeuf, F. and Parkinson, E., 2007. Numerical simulation of the flow in a Pelton turbine using the meshless method smoothed particle hydrodynamics: a new simple solid boundary treatment. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 2007.

2. Gingold, R. A. and Monaghan, J. J., 1977. Smoothed Particle Hydrodynamics: Theory and Application to non-Spherical Stars. Monthly Notices of the Royal Astronomical Society, vol. 181, Nov. 1977, p. 375-389.

3. SPH European Research Interest Community, 2011. SPHERIC Home Page. [online] Available at: <http://wiki.manchester.ac.uk/spheric/> [Accessed 15 February 2012]

4. Rafiee, A., S. Cummins, et al. (2012). "Comparative study on the accuracy and stability of SPH schemes in simulating energetic free-surface flows." European Journal of Mechanics - B/Fluids 36(0): 1-16.

5. Koukouvinis, P. K., J. S. Anagnostopoulos, et al. (2011). SPH Method used for Flow Predictions at aTurgo Impulse Turbine: Comparison with Fluent. World Academy of Science, Engineering and Technology 55 2011.

6. Zoppé, B., Pellone, C., Maitre, T. and Leroy, P., 2006. Flow analysis inside a Pelton turbine bucket. Trans. ASME J. Turbomach., 2006, 128, 500–511.

7. Jošt, D., Mežnar, P. and Lipej, A., 2008. Numerical Prediction of Efficiency, Cavitation and Unsteady Phenomena in Water Turbines. Proceedings of the 9th Biennial ASME Conference on Engineering Systems Design and Analysis. ESDA08. July 7-9, 2008, Haifa, Israel.

8. Benzon, D., Aggidis, G., Martin, J., Scott, J., Watson, A., 2013. State of the art & current research on Turgo impulse turbines. Clean Power Africa-Africa Utility Week, 14-15th May 2013 Conference, Cape Town, South Africa. Esi-Africa Online Power Journal http://www.esi-africa.com/wp-content/uploads/i/p/tech/Shaun-Benzon_HydroW.pdf [accessed 24/04/14]

9. Crewdson, E. (1922). Design and Performance of a New Impulse Water-Turbine. Minutes of Proceedings of the Institution of Civil Engineers, The Institution of Civil Engineers.

10. Gilbert Gilkes and Gordon Ltd, 2014. Gilkes Hydropower Brochure- Hydro turbine range http://www.gilkes.com/user_uploads/gilkes%20hydro%20brochure%202011.pdf [accessed 24/04/14]

11. Lancaster University Renewable Energy Group (LUREG). Hydro Resource Evaluation Tool: engineering options. [Internet]. [Cited 2014 April 18]. Available from: http://www.engineering.lancs.ac.uk/lureg/nwhrm/engineering/index.php?#tab

References