Francis turbines (which are water turbines) are the modern equivalent of water wheels that have been used over centuries for power generation. These devices are becoming essential for an environmentally-friendly and clean source of power and thus have evolved into complex designs that need to meet certain requirements in terms of performance and power output. This requires an ongoing optimization of the design of different components. Fluid flow simulation (CFD) is an alternative to complex, conventional development processes consisting of design development, prototype construction, and experimental validation. In this webinar, you will learn how the SimScale cloud-based simulation platform enables every engineer in the world to leverage the potential of CFD for their own projects in the field of power generation via water turbines by using a standard web browser (no installation or special hardware required). Follow us on LinkedIn: https://www.linkedin.com/company/simscale-gmbh/ And subscribe to our YouTube for more videos: https://www.youtube.com/channel/UCIi21t-7PVPNECXeAS0z7pw

1. WATER TURBINE DESIGN
OPTIMIZATION WITH CFD
JON WILDE and DARREN LYNCH

2. JON WILDE
Application Engineering Director
15+ years of experience in CFD, application
engineering, and team management.
Before joining SimScale, he worked with
many other CFD solutions and managed a
team of technical support engineers.

3. DARREN LYNCH
CFD Application Engineer
Experienced in CFD and engineering design,
Darren studied Aerospace Engineering at
Brunel University and is part of the
Application Engineering team at SimScale.

4. 1. Benefits of Using Simulation
2. Introduction to SimScale
3. Today’s Topic: Water Turbines
4. Live Demonstration
5. Results Summary
6. Q & A

8. ACCELERATE YOUR
DESIGN PROCESS
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durability or improve design efficiency
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11. WATER TURBINES
● A turbine - a big one!
● 150,000 hp
● This photo was taken on June
25th 1947
● Water turbines have been used
for over 135 years
Source: U.S. Bureau of Reclamation photo archives(Image originally uploaded to en.wikipedia by user
Pud) [Public domain], via Wikimedia Commons

12. GLOBAL ENERGY
● World energy demand is rising
rapidly
● Factors like climate change
require a shift from depleting
fossil fuels to renewable sources
of energy
● Hydropower currently
contributes to 16% of the
world’s power generation
Source: BP statistical review of World Energy, Delphi234 [CC0], via Wikimedia Commons

13. TYPES OF WATER TURBINES
Pelton
Wheel
Francis
Turbine
Kaplan
Turbine
1827
● Water turbines are the most
important component of a
hydropower system
● They are rotary machines that
convert the kinetic and potential
energy of water into mechanical
work
● Primarily used in electric power
generation applications
● Based on the head under which they
operate, they can be classified into
high, medium, and low head
Fourneyron
Reaction
Turbine
1849 1870 1913
(Source: https://media.giphy.com/media/l2JebisijdzVL2Cqs/giphy.gif)

14. KAPLAN TURBINE (0-60m pressure head)
Source: Uploaded by Duk [Public domain], via Wikimedia Commons
● Kaplan turbines are axial flow
reaction turbines
● The pressure of the fluid
changes as it flows through the
turbine
● Power is generated from both
the hydrostatic head and the
kinetic energy of water
● They are suited for low heads
and high flow rates

15. Pelton wheel from Walchensee, GFDL or CC-BY-SA-3.0, via Wikimedia
Commons
PELTON WHEEL TURBINE (300m-1600m pressure head)
● Impulse turbine, extracts energy
from moving water
● Water jets from high pressure
nozzles impinge on the spoon
shaped buckets
● The impulse force on the
buckets causes the disk to rotate
and generate power
● Mainly suited for high head
applications

16. FRANCIS TURBINES (60m-300m pressure head)
Source: Voith Siemens Hydro Power Generation [GFDL (http://www.gnu.org/copyleft/fdl.html) , via
Wikimedia Commons
● Impact & reaction turbine that
operate at a medium head, and
combine axial and radial flow
concepts
● They fill the large gap between high
head Pelton wheel and low head
Kaplan turbines
● The most commonly used water
turbines today, 60% of global
hydropower
● Creating more efficient designs is an
open challenge for engineers today

17. COMPONENTS OF THE FRANCIS TURBINE
Runner
Guide
Vanes
Draft
Tube
● Inlet Duct
● Spiral Casing
● Guide Vanes
● Runner & Runner Blades
● Draft Tube
Inlet
Outlet

18. COMPONENTS OF THE FRANCIS TURBINE
● Spiral Casing
● Guide Vanes
● Runner and Runner Blades

19. FRANCIS TURBINE IN OPERATION
Streamlines through a Francis turbine
● Water flows through a spiral casing
into the guide vanes (static)
● The guide vanes control the angle of
flow of water towards the runner
blades (moving)
● Water forces the runner to rotate
through a combination of impact and
reaction forces
● It then exits the runner to a draft tube
that discharges it to the environment

20. 1. CAD IMPORT
Upload your CAD model
or import it from other cloud
services into SimScale.
2. SIMULATION SETUP
All steps to define and run
a simulation are done
within SimScale.
3. DESIGN DECISION
Use simulation insights
to make better and faster
design decisions.
3

21. BOUNDARY CONDITIONS
● Inlet – volume flow rate
○ (8-16 m³/s)
● Outlet – static pressure (0Pa)
● Rotational speed (350 rpm)

24. FLOW THROUGH THE INLET DUCT
INLET DUCT
Draws water into the casing of the turbine
Has a converging passage area, to increase the kinetic energy of the water
Velocity within the inlet duct

25. ● The casing directs the water from the
inlet duct to the stator guide vanes
● The fluid velocity should be fairly
constant along its path towards the
guide vane
● The cross sectional area decreases to
maintain the velocity
FLOW THROUGH THE CASING
Flow through the casing

26. FLOW AROUND THE BLADES
Stator vanes guide the fluid onto the
runner blades at the angle appropriate to
the design
Due to the angle of incidence, the flow around the
second stator row experiences large separation

27. STATIC PRESSURE ON THE BLADES
Careful design should ensure that
the pressures on the blades do not
fall below vapor pressure of water,
as this would lead to cavitation.
Pressure Side
(front)
Suction Side
(rear)

28. ● The draft tube decelerates the
fluid from the exit of the runner
to the discharge
● This increases pressure and
minimizes the loss of kinetic
energy
● A good design is critical here to
avoid cavitation
FLOW THROUGH THE DRAFT TUBE
Static Pressure
Contour
Velocity Contour

29. ● There is a large recirculation
region in the tube caused by high
pressure gradients
● Let’s optimize the design here
FLOW THROUGH THE DRAFT TUBE
3D streamlines, showing the recirculation in the draft tube

30. Initial Design Modified Design
FIRST DESIGN MODIFICATION: DRAFT TUBE DESIGN

31. SECOND DESIGN MODIFICATION: STATOR ROW ANGLES
Initial Design Modified Design

32. DESIGN COMPARISON: FLOW THROUGH THE STATOR VANES
Initial Design Modified Design

33. DESIGN COMPARISON: FLOW THROUGH DRAFT TUBE
Initial Design Modified Design

34. DESIGN COMPARISON: FLOW THROUGH DRAFT TUBE
Initial Design Modified Design

35. DESIGN COMPARISON: PERFORMANCE CURVES
● The design modifications
implemented have led to an
increase of 1.5% in the peak
efficiency of the turbine
● Equivalent to an additional 450
Kwh of energy

36. ● We have improved the design
through CFD
● We also learned how to make a
design worse
○ This is the beauty of CFD
○ Parallel runs on the cloud
● We identified some issues and
know where to focus for further
efficiency gains
LESSONS LEARNED

37. ● The original design was not
optimum
● The draft tube modification
shows great promise
● The changes made to the stator
were less effective, we should
test again without these
modifications
LESSONS LEARNED
(Source: https://media.giphy.com/media/3HoB7BmMnKMdq/giphy.gif)