Conceptual Wing Sail Design for a Car Carrier

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Conceptual Wing Sail Design

for a Car Carrier

FILIP WÄNGELIN

Master in Naval Architecture Date: April 24, 2020

Supervisor: Mikael Razola, Ulysse Dhome Examiner: Jakob Kuttenkeuler

School of Engineering Sciences Host company: Wallenius Marine AB

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Abstract

Climate change if a fact and the responsibility comes down to the footprint owner. With a possible limitation on carbon oxide emissions and climate de-mands from customers, a change in the shipping industry is evident. A solution to this could be to use a renewable energy created by the nature, the wind, to make the change over to a climate friendly shipping industry. This study aims to find a wind powered solution for a car carriers propulsion. What is the most suitable rig design?

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Sammanfattning

Klimatförändring är ett faktum och ansvaret kommer till ägaren av klimatav-trycket. Med en möjlig begränsning av koldioxidutsläpp och klimatkrav från kunder är en förändring inom sjöfartsbranschen uppenbar. En lösning på det-ta kan vara att använda en förnybar energi skapad av naturen, vinden, för att klara övergången till en klimatvänlig sjöfartsindustri. Denna studie syftar till att hitta en vindkraftlösning för framdrivning av ett biltransportfartyg. Vad är den mest lämpliga riggdesignen?

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Chapter 1 Introduction

In 2005 Wallenius Marine AB presented a conceptual design of a zero emis-sion ship called E/S Orcelle as a final step on their roadmap towards Zero emission shipping. Now in 2019 together with SSPA and KTH this project got funding for further research to realizable the concept. The idea is to de-sign a wind powered car carrier and the goal is to be ready to order the ship from a shipyard at the end of 2020.

The ship is a wPCC (wind powered pure car carrier) with a hull design based on post panamax 7,500 RT PCC with four approximate 80 meter high rigs. The ship has three main propulsion methods, wind power, bio fuel and solar energy. This thesis will focus on the rig design and the functionalities required for a such large wing powered vessel.

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2 CHAPTER 1. INTRODUCTION

1.1 Research Question

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Chapter 2 Background

Seaborne shipping stands for 60% of world merchandise trade or 80% in vol-ume terms. The global shipping trade is growing at the fastest rate in the last five years, it is now at a four percent annually growth rate. According to UNCTAD (United Nations Conference on Trade and Development) the fore-cast showing an annual 3.8 % growth rate between 2018 and 2023 [1]. According to IMO GHG (Greenhouse Gas) Study of 2014 the international shipping carbon dioxide emissions were estimated to be equal to 2.2% of the global human-made emissions [2]. Recently the industry discussed limits to cut levels from a benchmark of 2008 carbon oxide emissions by 50% by the year 2050 [2]. If this limit becomes reality it will make a large impact on how new ships are designed and especially on propulsion choices.

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Chapter 3 Methods

This chapter aims at showing how to provide concepts and how to conceive/create solutions for different functional requirements.

3.1 Pre-study

The thesis work started out with a pre-study on the different wind powered solutions that have been used or conceptually used in the design of a wind powered ship. The aim of the study was to find already thought of/feasible solutions for the project and not "reinventing the wheel"; Some of the obvious concepts has probably already been thought of and if so, then most likely been tested or evaluated.

3.2 Concept design

Conceptual design processes often look the same, you got inputs, tasks and in the end one or more outputs. The same process was used in this report, the detailed view of the process will be explained in this section. The design process starts of with a few inputs such as; revised problem statement, require-ments and statement of deliverables. The task is then to come up with design functions and with those function generate concepts.

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CHAPTER 3. METHODS 5

3.2.1 Inputs

Revised problem statement

The task is to create the desired function/feature with the aim of solving dif-ferent requirements. Then generate conceptual design alternatives with the created functions/features, so the characteristics of the concept meets some or all requirements. The next step of a conceptual design process would be to compare and evaluate the concept designs and pick the best suited.

Rig requirements

Wallenius started the thesis by setting up some requirements on the rig. Those requirements was seen as a basis for desired features. The rig would most likely not have all of the requirements, but ideally a few important ones. Some of them contradicts each other, but whats important to look at is the benefit of the requirement. It is impossible to both have a symmetric and cambered profile at the same time, but maybe it is possible to have the benefits of both. So a work around these requirements was a good start, trying to find solutions to a desired requirement. The feasibility and the complexity of the deliverable features was a key factor of the importance of a desired feature. The stated requirements was:

• Variable area - Able to decrease the area and therefor decrease the force acting on the rig

• Variable height - Lower the total height of the ship when passing a bridge or when staying in port

• Twist - Control the load distribution along the height of the rig by either control or having a fixed twist on the longitudinal axis

• Symmetric wing profile - The ease of being able to tack without chang-ing the shape of the rig

• Camber Profile - Higher lift coefficient wich can result in smaller/fewer rigs

• Passive vaneing - Safety feature that allows the rig to vane when in a dead ship condition for instance

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6 CHAPTER 3. METHODS

• Lockable rotation anywhere/anytime - Control the angle of attack with precision and not having intervals of locking points

• Operational during harsh climate (ice, snow, rain) - A design which will not depend on optimal conditions regarding wind and to many exposed moving parts

• Accessible for maintenance and inspection - E.g by having control me-chanics and moving parts reachable from the deck with reasonable main-tenance equipment

• Structural design against loads exposed to - Reasonable volumes for structural components (beams etc)

• Adjustable angle of attack - Being able to change the lift/drag generated by the rig

Statement of Deliverables

The aim of this report is to generate many feasible solutions to the set require-ments, preferably complete concepts and evaluate those to get the benefits and drawbacks of each generated solution. This will help the future work to evalu-ate and compare different solutions. The aim is not to pick the most promising concept but to widen the ideas for further work in the design of the rig for the next Wallenius ship.

3.2.2 Task

Establish desired design features

One conceptual design contains of one or more features with one or more func-tions. E.g if a car is seen as a concept then the headlights is a feature with the function of lighting up the street at night. So by looking at the requirements set from Wallenius the idea is to solve a feature that fulfills the required func-tion. One feature could be to mount a flap to an airfoil, with the function of manipulate the lift-/drag coefficient of the wing.

Generate conceptual design alternatives

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CHAPTER 3. METHODS 7

concepts less is truly more when looking how feasible the generated concept are. A full catalog of generated designs is presented in Appendix A.

3.3 Mechanical design

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Chapter 4 Results

The result of this thesis is two concepts who stuck to be interesting throughout the thesis period and a catalog of concepts that could be used for further work of finding the optimal wing solution for the next Wallenius ship. The catalog is presented in Appendix A.

4.1 Retractable flap

The idea behind having a retractable flap is to decrease area, but also to be able to increase lift coefficient by deflect the flapped surface. The wing will go from a symmetric profile to a cambered and thus give higher lift coefficient. This concept has been looked in to deeper due to its potential to fulfill a few of the requirements. A illustrative figure is presented below.

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CHAPTER 4. RESULTS 9

Figure 4.1: Symmetric wing profile with a retractable flap

Mechanical solution

The mechanical problem is to be able to actuate the flap with a simple but robust solution. The Solution is based on gears with tracks, so the flap will be actuated with gears on the flap running on tracks inside the slot of the wing. A internal view of the mechanical design is shown in the figure below.

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10 CHAPTER 4. RESULTS

4.2 Telescopic retractable rig

The telescopic retractable rig is a feature more than a concept even tho it al-ready fulfills a few desired functions. The obvious ones being "Variable area" and "Variable height". The effect of being able to reduce the area and doing so in the height is extremely beneficial in stormy conditions. To illustrate this, a simple structural study was made.

Figure 4.3: Telescopic retractable rig

Structural study

The study substitute the wing with a cantilever beam with variable cross sec-tions. The load acted on the beam is calculated with DNV-GL’s upper bound of an extreme load, which in this case is an apparent wind speed of 56 m/s at 110m over the sea. The wing is assumed to be a squared 2000 m2 _{rig with}

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Figure 4.4: Beam dimensions

The figure below shows the comparison of the deflection on a retracted versus extended beam.

Figure 4.5: Extended vs Retracted telescopic mast

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12 CHAPTER 4. RESULTS

We see that the maximum bending stress gets up to 800 Mpa which is way over the yield tensile strength of normal steel (about 350 Mpa). If we look at the same example but with a retracted rig.

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the yield tensile strength of steel. Looking at this comparison it is easy to see the benefit of having a retractable wing. The difficult part is to make the mechanical solution simple enough to withstand the load and be operational in harsh conditions.

Mechanical solution

A large inspiration source to the solution comes from cranes, mobile crane in particular. Looking at the dimension they are pretty similar, the bigger ones can extend up to 100m and weighs around 100 tonnes. The biggest difference is the load cases. The load on a wing will always be in radial direction of the mast, except the weight of the wing itself. But for the mobile cranes the load is a combination of axial and radial loads, with most of the load being in axial direction. So a mast would be taking higher bending moments than the mobile crane.

Figure 4.8: Loads action on the rig

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Chapter 5 Discussion

The results might suggest that the most important property of a wing design is its ability to depower or control the load exposed to. However, it depends on the type of demand from the buyer. For this kind of a ship, safety is key and there is not enough knowledge of what kind of performance is expected. In the start of the study a lot of performance enhancing designs were thought of, but as time went, depower and twist came up as the most interesting properties. Looking at the resulting concepts it might look like a hard wing sail type rig is more of a suitable design alternative than soft sail designs. That is not nec-essarily true in every case. Why soft sails were almost completely ruled off in the report was due to the ship which is designed to be out sailing day and night and with sails that needs to be changed every 3500 hours (which is the normal life span of soft cloth sails). That would mean a yearly change of sails. If one want to design a rig for a ship that has a up-time of a few hours a week, soft sail are probably the cheapest and best solution.

The deciding factor of what solution to work further on and which solution that got scraped in an early stage was the feedback from Wallenius Marine. So the results has been shaped by both the study and the desire of the company. The telescopic solution was something that very early on was an interesting concept. But in that case the mechanical solution was important to understand to be able to evaluate the concept. Therefore a deeper study was made on the mechanical solution and how it could be made. The application was used in mobile cranes and they were too expecting heavy loads, the main different is the uncontrolled loads with wind and weather changes. The concept also checked off most requirements set in the beginning, the obvious ones being:

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CHAPTER 5. DISCUSSION 15

"Variable area and height", "Symmetric wing profile", "360 degrees swivel", "Lockable rotation", "Adjustable angle of attack". The ones that is more diffi-cult to say at this stage is "Operational during harsh climate", "Accessible for maintenance" and "Structural design against loads exposed to".

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Bibliography

[1] United Nations. “Development in International Seaborne Trade”. In:

RE-VIEW OF MARITIME TRANSPORT. 2018.

[2] International Maritime Organization. “CO2 emissions from international shipping”. In: Third IMO Greenhouse Gas Study. 2015.

[3] VPLP Design. “Ocenawing”. In: https://vplp.fr/realisation/oceanwings/58.html. 2017.

[4] Magma Structures. “Dyna-rig”. In:

http://www.magmastructures.com/project/superyacht-dynarigs/. 2018.

[5] Dykstra Naval Architects. “Ecoliner”. In:

http://www.dykstra-na.nl/designs/wasp-ecoliner/. 2018.

[6] Cruisingworld. “How Long do Sails Last?” In:

https://www.cruisingworld.com/how-long-do-sails-last/. 2016.

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Appendix A

Conceptual Designs

This appendix is meant to be a catalog of concepts generated during the design process. The thought process behind the solutions and the benefits/drawbacks is presented on each solution.

Playcard 1 - Flapped wing

Airfoil design with a flap mechanism that can increase/decrease area and/or lift coefficient

Figure A.1: Flappeded wing

This concept aims to have a wide range of optimal wind speeds, with the core function to decrease the area of the wing in harsh conditions. There are alternative designs to this concepts one being able to deflect the flap when fully extended (See figure below). This will create a cambered wing profile but still keep the benefits of having a symmetric wing. The cambered wing

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18 APPENDIX A. CONCEPTUAL DESIGNS

will have a higher lift coefficient and therefore be well suited for low wind speed condition.

Figure A.2: Flap deflection

Another alternative design is to split the flap up in to sections each be con-trolled individual (See figure below). This could both be used with or without flap deflection. The benefit of this is that one can control the load distribution over the length of the mast. Not only controlling the area distribution of the wing but also controlling the lift coefficient over the length of the mast.

Figure A.3: Flap sections

Benefits: This concept has the ability to change its characteristics depending

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APPENDIX A. CONCEPTUAL DESIGNS 19

gives the opportunity to sail in a wide range of wind speeds. It has the benefits of a symmetric wing when looking at tacking and gybing due to the asym-metry being controlled with the flap. By having the flap in sections it is also possible to have load distribution control.

Drawbacks:This concept has no full depower solution without being forced

to fold the whole structure. This threat is common in hard wing sails but still a big concern. A large portion of the weigh in this design could come from structure holding the flap and the actuation behind that. This could result in large mass being place high up, which has negative aspects to the ships stabil-ity.

Playcard 2 - Multi wing

Double airfoil configuration with control of the relative angle towards each other

Figure A.4: Multi wing configuration

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control of load distribution (See figure below).

Figure A.5: Twist crontrol

Another alternative is to have the second wing in a flexible/foldable surface that can be furled down to decrease the area of the wing. This is shown in figure below. This will effectively reduce a big portion of the area for harsh conditions. The drawback being that the second wing will have higher wear and need for replacement due to the short lifespan of softer sails.

Figure A.6: Twist crontrol

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Figure A.7: OceanWing

Benefits: The key benefit of this concept is its performance, different

calcu-lations has shown a lift coefficient of close to double the lift of a symmetric airfoil of same size. This combined with the ability fully depower with a fold-able solution is very promising. With the angle control its also easy to tack or gybe since the wing is able to mirror the desired shape.

Drawbacks: There is not in this concept any solution to reduce height. The

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Playcard 3 - Morphing

Airfoil with active morphing shape

Figure A.8: Morphing wing

This concept is using a thin flexible surface wrapped around a mast and control rods going out horizontally of the trailing edge of the mast. The shape of the airfoil is changed with the rods holding on to the trailing edge of the surface. The result is a airfoil that can both be symmetric and asymmetric depending on the desired lift. The effect is not as huge as the previous concepts but can make a difference in sizing of the wings. A comparison of a Naca 0012 and a Naca 6409 (which is a common symmetric vs a common asymmetric airfoil profile respectively) is shown below.

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An addition to this concept would be to have the surface in a soft cloth that can be furled into the mast much like modern sail yachts have today. If the rods also is retractable the sail could have variable area by partly furl in the cloth and thus reduce cord length.

Benefits: "Best of two worlds" by having a symmetric wing with the

abil-ity to morph into a cambered one. Easy to tack and gybe with higher lift than a symmetric wing profile. The soft surface allows for twist which i great for load distribution control. This combined with variable cord length gives op-portunities for operability in a wide range of weather conditions.

Drawbacks: The softer sails has a shorter lifespan due to the easy wear of

the cloth. This might result in more maintenance and longer down times. The surface is also weak against tears and rips if a cloth is used, which makes it less robust compared to a composite surface. The composite surface would of course not be furlable and thus not reefable though.

Playcard 4 - Vane

Freely rotatable airfoil design with a controllable flap which is used to set the angle of attack

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This concept used a rigid symmetric wing which can rotate freely, the only rotational force comes from its flap. So it works like a vane, used to show the direction of the wind. If the freely rotatable mast is placed at the aerodynamic center and the flap has and some deflection the wing itself will get an angle of attack. Since the lift will act on the centre of rotation it will not create any rotation. It is therefore self adjusting with fixed angle of attack. An alternative to this concept would be to split the top part of the wing into sections. Those section would then be used to allow for twist (See figure below).

Figure A.11: Vane wing with sections

Another interesting aspect of having the wing in sections is the possibil-ity for telescopic retraction. This adds both variable area and variable height which is two functions that is sought-after.

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Another option would be to add flaps to each sections, so that each sections can be controlled individually and passive (See figure below). This only makes sense if you think of the wind direction changing with altitude. Which in this case can be quite a lot in work cases.

Figure A.13: Fully vaneing sections

This concept could be combined with other wing designs. The idea is to have one vaneing wing that controls the angle of attack of all wings. So by connecting the rotation of all of the wings and have one wing vaneing with a flap. Configuration is shown in figure below. This can benefit from having three high performance wings and one controlling one. This configuration does not have the same clearance issues as it would with four vaneing wings.

Figure A.14: Fully vaneing sections

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sumption during "flight". One big benefit to this concept is in a "dead ship" condition. The sails could have a safety feature that sets the angle of attack to zero and leaving the sails vaneing in to the wind creating zero lift.

Drawbacks: The concept assumes a symmetric wing which has relative low

lift coefficient compared to a flap/asymmetric wing design. Without the tele-scopic retraction there is no reefing or control of lift except angle of attack. So it needs to be folded in a tilting motion to depower i port. Since the flap bene-fits from being as far from the wing as possible a rotational clearance is a treat in this design. It is difficult to make four of these sails in a row configuration without clearance issues.

Playcard 5 - Stacking wing

Stack-able and reversible asymmetric wing

Figure A.15: Stack-able wing design

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Figure A.16: Flap/slat wing design

Benefits: This concept can be fully depowered which a lot of concepts do not

have. This is not only a huge benefit in port but also in conditions were sailing would be dangerous. Another benefit is that the profile could be design how-ever the shipowner would like, if lift force is the key property then a cambered profile with both slats and flaps can be used.

Drawbacks: One big disadvantage of this design is that each section will

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Playcard 6 - Dynarig

Conventional squared rig with booms and soft sails

Figure A.17: Dynarig

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Figure A.18: Ecoliner

Benefits: The obvious one being that it exist and in about the same scale. The

cloth can be furled and there for has a full depower setting, a key requirement in port or when operating in heavy wind. Since the sails are split up into five smaller sails the load on each sail is smaller and can therefor be made in a thinner and lighter material.

Drawbacks:Same as every concept with soft sails the maintenance is a large

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Appendix B

Detailed view of the telescopic

lock pin mechanism

This appendix is a guide how the internal mechanism of the pinned boom func-tions.

The first figure shows a zoomed in view of the internal cylinders and piston in the center of the lower section. First we got a hydraulic piston (in torques color) which can extend one section in length. So one full telescopic extension cycle would include one full extension plus retraction of the piston per section.

The cycle starts of with the hydraulic piston locking into the first section

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APPENDIX B. DETAILED VIEW OF THE TELESCOPIC LOCK PIN

MECHANISM 31

of the wing with the pin. Then extends until it lines up its lowest edge to the second section’s top edge.

At this point the red actuator locks the first to the second section with the pin. So by now the top section is locked in place. The piston can now detach the pin and retract down.

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32 APPENDIX B. DETAILED VIEW OF THE TELESCOPIC LOCK PIN MECHANISM

actuator. It is because the actuators fork shaped connection to the pin with a matching slot.

Conceptual Wing Sail Design for a Car Carrier