Post on 14-Mar-2021
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
ASYMMETRIC SPINNAKERS:DOWNWIND RACING YACHT SAILS RESEARCH AND FINDINGS
1 0 T H S E P T E M B E R 2 0 1 9
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
ASYMMETRIC SPINNAKERS:DOWNWIND RACING YACHT SAILS RESEARCH AND FINDINGS
1 0 T H S E P T E M B E R 2 0 1 9
JB
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
CONTENTS
3
1. History
2. Upwind vs Downwind Sailing
3. Wind Tunnel Testing of Yacht Sails
4. Aerodynamics of the Circular Arc
5. Leading Edge Vortex
6. Conclusions
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
1. HISTORY
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 5
HISTORY
Round the world racing with very close finish?
2012-2013 Vendee Globe: 3 hours 17 min between the first and second after 78 days at see
1866 – Tea Race, Taeping won by 28 minutes after 99 days at sea
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 6
HISTORY
Catamaran for the America’s Cup?
2010s
1877 – Herreshoff proposed AC catamaran
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 7
HISTORY
Foiling Yachts?
Latest trend
Started in 1898
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 8
HISTORY
Canting keel yachts?
1930s
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
2. UPWIND VS DOWNWIND SAILING
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
UPWIND WIND TRIANGLE
VTVA
βT
βA
True Wind Speed
(TWS)VT
Velocity of the wind relative to a
stationary object.
True Wind Angle
(TWA)βT
Angle between TWS and yacht’s
heading.
Boat Speed VB Velocity of the yacht.
Apparent Wind
Speed (AWS)VA
Velocity wind relative to a moving
object.
Apparent Wind
Angle (AWA)βA
Angle between AWS and yacht’s
heading.VB
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
UPWIND SAILING EQUILIBRIUM
CL
Boat Track Yaw
VA
βA
Sail Lift
Sail Drag
Aerodynamic ForceSail Side Force
Keel Side ForceHydrodynamic Force
Drive
Drag
𝑭𝑫 = 𝑳𝒔𝒊𝒏𝜷𝑨 −𝑫 𝒄𝒐𝒔 𝜷𝑨
𝑺𝑺𝑭 = 𝑳 𝐜𝐨𝐬𝜷𝑨 +𝑫 𝐬𝐢𝐧 𝜷𝑨
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
DOWNWIND SAILING
Historically: Vessels sailing downwind
1865: First spinnaker, dedicated downwind sail
1970s: Symmetric spinnakers
1990s: Asymmetric spinnakers (aka Gennaker)
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
SYMMETRIC SPINNAKER
Drag generating sail
VB
VT
VA
Drag
Lift
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
ASYMMETRIC SPINNAKER
Lift generating sail
VB
VT
VA
Drag
Lift
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
ASYMMETRIC SPINNAKER
Lift generating sail
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
3. WIND TUNNEL TESTING OF YACHT SAILS
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 17
THE IMPORTANCE OF SAIL FORCES
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 18
THE IMPORTANCE OF SAIL FORCES
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 19
TWISTED FLOW WIND TUNNEL
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 20
TWISTED FLOW WIND TUNNEL
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 21
TWISTED FLOW WIND TUNNEL
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 22
TWISTED FLOW WIND TUNNEL
Atmospheric boundary layer effect
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 23
TWISTED FLOW WIND TUNNEL
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 24
TWISTED FLOW WIND TUNNEL
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 25
TWISTED FLOW WIND TUNNEL
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 26
VELOCITY PREDICTION PROGRAM
The output from the wind tunnel testing then feature in the Velocity Prediction
Program (VPP)
Surge (x): Longitudinal movement of the yacht
Sway (y): Transverse movement of the yacht
Heave (z): Vertical movement of the yacht
Roll (ϕ): Rotation about the longitudinal axis
Pitch (θ): Rotation about the transverse axis
Yaw (β): Rotation about the vertical axis
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 27
POLAR PLOT
The polar plot resulting from the VPP presents: True Wind Angle
Boat Speed
Speed achieved with a particular sail…
… in a particular True Wind Speed
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 28
POLAR PLOT
It is also used to assess the best Velocity Made Good (VMG)
VB
VTVA
VMG
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 29
VELOCITY MADE GOOD
Wind
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
REAL TIME VPP
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019
WIND TUNNEL TESTING
BUT…
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
4. AERODYNAMICS OF THE CIRCULAR ARC
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 33
BACKGROUND
Wind Tunnel assumption: the flow is turbulent (at the scales
typically tested in dedicated wind tunnel facilities)
Inconsistencies noticed in the pressure distribution on wind
tunnel tested models Some exhibit laminar separation bubbles while others do not.
This is characterized by a plateau in the spanwise pressure coefficient
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 34
BACKGROUND
Low Reynolds number: discontinuity in the lift and drag (Lombardi, 2014)
Abrupt change in separation point at the same angle (Martin, 2015)
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 35
HYPOTHESIS
Hypothesis: these is a combination of critical Reynolds number and critical angle of
attack that will trigger transition.
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 36
GEOMETRY
Specifications: Highly cambered: 22.32%
Thin: 1.8mm thick
Chord: 200m
Sharp leading edge
Manufacturing: Carbon prepreg
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 37
FORCE MEASUREMENTS
Force measurements undertaken in Solent University’s Hydrodynamic Test Centre: Reynolds numbers: 53k, 68k, 150k and 220k
Angles of Attack: 5 to 20 (5 to 25 at 53k) in 1 degree increments
Angle of attack of 11 degrees for 130k < Re < 160k
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 38
FORCE MEASUREMENTS VALIDATION
Validated against Velychko’s (2014) wind tunnel experiment.
Velychko, 2014
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 39
FLOW DIAGNOSTICS – PARTICLE IMAGE VELOCIMETRY
Current flume at the University of
Edinburgh
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 40
FLOW DIAGNOSTICS – PARTICLE IMAGE VELOCIMETRY
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 41
PARTICLE IMAGE VELOCIMETRY – FLOW FIELDS
Delayed separation consistent with the values of Martin (2015) and reduced wake,
characteristic of laminar to turbulent transition.
Sub-Critical
AoA = 14ºSuper-Critical
AoA = 15º
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 42
PARTICLE IMAGE VELOCIMETRY – FLOW FIELDS
Delayed separation consistent with the values of Martin (2015) and reduced wake,
characteristic of laminar to turbulent transition
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 43
NON-DIMENSIONAL TURBULENT KINETIC ENERGY
𝑢′2 + 𝑣′2 2𝑈∞2
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 44
NON-DIMENSIONAL TURBULENT KINETIC ENERGY
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 45
NON-DIMENSIONAL TURBULENT KINETIC ENERGY
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 46
IDEALISED MODEL
Idealised Lift Coefficient:
The flow is turbulent above a critical Reynolds
number of 220k irrelevant of the angle of
attack
Below 220k, there is a combination of
Reynolds number and angle of attack that will
induce transition
What angle of attack is needed to inflate
a soft spinnaker?
And what is the associated Reynolds
number to guarantee a turbulent flow?
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 47
IDEAL ANGLE OF ATTACK
11 degrees is the ideal angle of attack
A minimum Re of 144k (±2k) is required
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 48
APPLICATIONS
Now allows to explain the inconsistencies noticed: Model & full-scale experiments with a high enough Reynolds number are still valid
Model scale experiments at too low a Reynolds number should be discarded
Interesting case of Bot et al. 2014: LSB at the shallowest AWA
Suggest the critical AoA for that Reynolds
number was not reached yet
Higher AWA however appear to be above the
critical AoA to trigger transition
We can now ensure model scale
experiments appropriately replicate the
full-scale turbulent separation on
spinnakers
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
5. LEADING EDGE VORTEX
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 50
BACKGROUND
Leading Edge Vortex (LEV): Coherent vortex formed by a roll up of vorticity at the leading edge
Vorticity convected towards the centre of the vortex
If vorticity if extracted from the axis of the vortex, a stable LEV is achieved
Vorticity is typically extracted inside the vortex core towards the tip of the wing
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 51
BACKGROUND
Evidence of LEV on: Delta Wings (1960s)
Insects (1996)
Birds (2004)
Spinnakers (2014) – Numerically
Spinnakers (2017) - Experimentally
“Birds can’t fly”
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 52
LEADING EDGE VORTEX
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 53
LEV ON SPINNAKERS
Current research question: LEV on thin wings with a sharp leading edge?
How to promote the development and stability of the LEV?
Design characteristic affecting the LEV and its stability?
Performance gain?
Up to +25% Lift
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 54
OTHER APPLICATIONS
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 55
OTHER APPLICATIONS ?
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
Mercedes-AMG Petronas
Aerodynamic Department Lecture
SOLENTU N I V E R S I T Y
6. CONCLUSIONS
Jean-Baptiste R. G. Souppez Mercedes-AMG Petronas Aerodynamic Department Lecture – 10th September 2019 57
CONCLUSIONS
1. History
2. Upwind vs downwind
3. Wind tunnel testing
4. Aerodynamics of the circular arc
5. Leading edge vortex
Reference: Souppez, J.-B. R. G., Arredondo-Galeana, A. & Viola I. M.,‘Recent Advances in Downwind Sail Aerodynamics’, The 23rd Chesapeake Sailing Yacht Symposium,
Annapolis, Maryland, United States, 2019.
Souppez, Arredondo-Galeana & Viola, 2019.
SOLENTU N I V E R S I T Y
Jean-Baptiste R. G. Souppez
Senior Lecturer in Yacht Design and Composite Engineering
jean-baptiste.souppez@solent.ac.uk
THANK YOU