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COMPUTATIONAL ANALYSIS OF THE FLOW OVER A ROTORBLADE AND HYDROFOIL PROFILEAbbhelash Sajitha Menon (11851211) 17 December 2021 (has links)
The objective of this study is to computationally investigate the vorticity generated by the wake of a (1) rotor blade and a (2) hydrofoil profile. The first flow is weakly compressible and is inspired by experiments carried out by Dr. Tinney at The University of Texas at Austin aimed at investigating the aeroacoustic effects of blade-vortex interactions. The second flowis inspired by experiments carried out by Dr. Irvine at the University of Chicago where a ring with a hydrofoil-shaped cross-section is pulled in water to create a coherent vortical structure. Simulations have been carried out with the high-order unstructured block-spectral code solverH3AMR. The rotor blade simulations have been performed at the nominal angle of attackof 7.4°where an unsteady vortical wake with quasi-periodic shedding was observed together with a surprising dependency of the lift coefficient on the thermal boundary conditions: the lift coefficient is predicted to increase from 0.96 to 1.14 when switching from adiabatic to isothermal no-slip conditions. The hydrofoil calculations were run with steady free-stream conditions (not matching the experiments) and showed massively separated flow on the suction side due to the high angle of attack.
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Hybridn modely turbulence pro silnÄ zaven© proudÄn / Hybrid turbulence models for strongly swirling flowsKapln, Martin January 2020 (has links)
The aim of this paper is to investigate using of hybrid turbulence models for strongly swirling flows. The work is focused on the possibility of applying a hybrid SBES model to simulate flow around a hydrofoil. The work further describes the creation of a mesh for the solved domain, the setting of boundary conditions and the setting of the solution for the software FLUENT. The simulation results are compared with experimentally measured values. The work also uses and evaluates data from PIV measurements. The knowledge that the paper brings as part of the results of a research project can be applied in the future in the design of blades of water turbines.
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The use of hydrofoil on electric seaplanes in the future transportation system / Användningen av elektriskt foilande sjöflygplan i framtidens transportsystemBroström, Elvira January 2024 (has links)
Runt om Sverige och världen växer efterfrågan av snabba, smidiga och miljövänliga resor och transportsätt. Transporter inom skärgården och över vatten sker till största delen idag med olika färjor och båtar. Dessa transporter är oftast begränsade till vissa sträckor, tar lång tid samt släpper ut gifter i naturen. Genom att använda elektriska sjöflygplan kan möjligheter att transportera sig i skärgården öka kraftigt och öppna möjligheterna att snabbt och miljövänligt, resa långa sträckor över vattnet. Sjöflygplanen, som kommer vara foilande med hydrofoils, ger flera fördelar vid användning. Rapporten ger läsaren en inblick i hur elektriskt foilande sjöflygplan kan komma att användas i framtiden. Genom en litteraturstudie, har empiriska data tagits fram som lagt grund till analys över hur elektriskt foilande sjöflygplan kan användas i framtiden. / <p>Examensarbetet är utfört vid Institutionen för teknik och naturvetenskap (ITN) vid Tekniska fakulteten, Linköpings universitet</p>
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The Design, Verification, and Validation of a Personal Hydrofoil CraftDougherty, Hugh Raymond Robert 02 February 2024 (has links)
The VT i-Ship Lab has been assigned the task of designing and building a Personal Hydrofoil Craft capable of carrying two people, featuring the distinctive capabilities of foiling and diving. This thesis examines the attributes of fully submerged hydrofoils and their prospective advancements. Diverse configurations of fully submerged hydrofoils are scrutinized, accompanied by an exploration of their respective stability characteristics. A comprehensive analysis is conducted on the design space trade-offs, incorporating potential flow-based methodologies such as the lifting line and vortex lattice methods, encompassing considerations for the free surface, structural computations, and propulsion optimization. In conjunction with the design study computational fluid dynamics is employed to verify the estimated values and to fine-tune the system allowing for a robust low-fidelity system that can quickly estimate the appropriate hydrofoil arrangement for the desired conditions. Various hydrofoil and craft configurations are explored discussing the trade-offs with a final design being chosen and a thorough mechanical design pursued. / Master of Science / The VT i-Ship Lab is conducting research on a watercraft known as a "Personal Hydrofoil Craft." This vehicle is designed to carry two people, glide on the water's surface, and dive underwater. Hydrofoil crafts use specialized underwater wings to reduce resistance and enhance efficiency. Our focus is on fully submerged hydrofoils, studying their stability and efficiency. We employ computer simulations and advanced methods to design and optimize these submerged hydrofoils. The goal is to enhance our understanding of their functionality and performance through real-life experiments. This research has the potential to improve watercraft technology, leading to more efficient and stable boats in the future. By exploring the science behind hydrofoil designs, we aim to contribute valuable insights to the field of water transportation.
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Structural Integrity Analysis of Hydrofoil on a marine vesselJonsson, Joel, Hofverberg, Fabian January 2024 (has links)
This study investigates the structural integrity of hydrofoils under three scenarios: regular boating, turning, and collision with an underwater obstacle. To analyse the forces acting on the hydrofoil, calculations were performed and simulations were conducted in SolidWorks using a CAD model of the hydrofoil.The simulations reveal that the weld between the struts and the wing undergoes plastic deformation during both regular boating and turning. This deformation is particularly problematic during turning, as the forces on the weld increase significantly. Under the collision scenario, the bolts at the breakpoint fail before critical damage occurs to the components above.The results highlight the weakness of the weld and the need for a redesign of the hydrofoil to eliminate it. An alternative fastening method, such as bolted joints with watertight sealing, should be considered.
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Multi-Fidelity Structural Modeling For Set Based Design of Advanced Marine VehiclesRaj, Oliver Neal 22 May 2018 (has links)
This thesis demonstrates that a parametrically-modifiable Advanced Marine Vehicle Structural (AMVS) module (that can be integrated into a larger framework of marine vehicle analysis modules) enables stakeholders, as a group, to complete structurally feasible ship designs using the Set-Based Design (SBD) method. The SBD method allows stakeholders to identify and explore multiple solutions to stakeholder requirements and only eliminating the infeasible poorer solutions after all solutions are completely explored. SBD offers the and advantage over traditional design methods such as Waterfall and Spiral because traditional methods do not adequately explore the design space to determine if they are eliminating more optimal solutions in terms of cost, risk and performance.
The fundamental focus for this thesis was on the development of a parametrically modifiable AMVS module using a low-fidelity structural analysis method implemented using a numerical 2D Finite Element Analysis (FEA) applied to the HY2-SWATH. To verify the AMVS module accuracy, a high-fidelity structural analysis was implemented in MAESTRO to analyze the reference marine vehicle model and provide a comparison baseline. To explore the design space, the AMVS module is written to be parametrically modified through input variables, effectively generating a new vessel structure when an input is changed. AMVS module is used to analyze an advanced marine vessel in its two operating modes: displacement and foil-borne. AMVS demonstrates the capability to explore the design space and evaluate the structural feasibility of the advance marine vehicle designs through consideration of the material, stiffener/girder dimensions, stiffener/girder arrangement, and machinery/equipment weights onboard. / Master of Science / In designing large marine products, it is necessary to follow a structured process to ensure the final product adequately meets the needs of a stakeholder’s requirements through engineering verification and validation analyses steps. This thesis demonstrates that the Advanced Marine Vehicle Structure (AMVS) module can be used by marine engineering professionals, in a group, to quickly analyze many structural variations of an advanced marine vehicle without freezing or locking in on an early and potentially suboptimal design. AMVS is intended to be integrated and to work in conjunction with other marine vehicle modules that, together, shipbuilder engineers can use to analyze all major design aspects of the marine vehicle in the total ship design process. Together the modules are implemented as a Set-Based Design (SBD) process to explore multiple total advance marine vehicle solutions to the stakeholder’s requirements and to eliminate the infeasible and worse solutions later during analysis.
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Simulations of a self-stabilizing fully submerged hydrofoil / Simulering av ett självstabiliserande helt nedsänkt bärplanssystemJacobson, Henry January 2023 (has links)
Two models of a self-stabilizing hydrofoil system is developed where the effects from the struts and hydrofoil give torques for angular rotations. Lifting line theory for the hydrofoil which can twist is used. Nonlinear versions of the models are also developed and compared to find that the linear models use valid approximations. Backward Differentiation Formula is used to get numerical solutions, and eigenvalues of linear system matrices are used to get stability regions. The models did not accurately capture what has been seen in testing. / Två modeller för ett självstabiliserande bärplanssystem utvecklas där effekter från stöttor och bärplan ger vridmoment för vinkelrotationer. Lyftande linjeteori för det skevande bärplanet används. Icke-linjära versioner av modellerna tas också fram och jämförs för att finna att de linjära modellerna använder giltiga approximationer. Backward Differentiation Formula används för att fram numeriska lösningar, och egenvärden i det linjära systemetsmatriser används för att hitta stabilitetsregioner. Modellerna fångade inte korrekt vad som har setts i testning.
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A passive suspension system for a hydrofoil supported catamaranKopke, Markus 03 1900 (has links)
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2008. / This study investigates practical passive methods to improve the seakeeping of a
Hydrofoil Supported Catamaran (Hysucat). The Hysucat is a hybrid vessel combining
hydrofoil efficiency with the stability of catamarans.
The seakeeping of the Hysucat was initially investigated experimentally to determine
what seakeeping improvements are inherent to the Hysucat design. The results
showed that the seakeeping is improved by 5-30%.
A passive suspension system for the main hydrofoil of the Hysucat was designed and
tested. A concept development strategy was followed for the design of the suspension
system as such a system had never been investigated previously. Detailed
specifications for the design were developed and concepts that could satisfy the
customer and engineering requirements were generated.
Numerical simulation models for the Hysucat and the final concepts were derived
assuming a simplified 2nd order system to describe the seakeeping dynamics of the
demi-hulls. Unknown parameters were determined using parameter estimation
techniques. Representative parameter values were calculated from multiple towing
tank experiments. Theory describing the motion of a hydrofoil in an orbital velocity
wave field was combined with the hull model to simulate the Hysucat as well as the
suspension system concepts.
The models indicated that the concept where the main hydrofoil was attached to a
spring loaded arm, that was free to pivot in response to orbital waves, was the most
feasible in damping out vertical transmitted accelerations. Experimental tests indicated
that little improvement was achieved with the suspension system at low frequencies. At
resonance the suspension system was effective in decreasing the heave of the vessel
by up to 27%. The pitch and acceleration response results showed improvements at
the higher encounter frequencies of up to 50%. The calm water resistance of the vessel
increased by 10% over the Hysucat with rigidly attached hydrofoils; however was still
24% less than the hull without foils.
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Design and optimization of hydrofoil-assisted catamaransMigeotte, Gunther 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: This work is concerned with the hydrodynamic design of hydrofoil-assisted catamarans.
Focus is placed on the development of new and suitable design methods and
application of these to identify the most important geometric parameters of catamaran
hulls and hydrofoil configurations that influence efficiency and performance. These
goals are pursued by firstly gaining a thorough understanding of the governing hydrodynamic
principles involved in the design process. This knowledge is then applied to
develop new and improved experimental techniques and theoretical methods needed
for design. Both are improved to the extent where they can be applied as design
tools covering the important semi-displacement and semi-planing speeds, which are
the focus of this study.
The operational speed range of hydrofoil-assisted catamarans is shown to consist of
three distinct hydrodynamic phases (displacement, transition and planing) and that
different hydrodynamic principles govern vessel performance in each phase. The hydrodynamics
are found to differ substantially from that of conventional high-speed
craft, primarily due to the interaction between the hull and the hydrofoils, which
is found to vary with speed and results in the need for more complex experimental
procedures to be followed if accurate predictions of resistance are to be made.
Experimental predictions based on scaled model tests of relatively small hydrofoilassisted
catamaran models are found to be less accurate than that achievable for
conventional ships because of the inability to correct for all scaling errors encountered
during model testing. With larger models scaling errors are encountered to a lesser
degree. The most important scale effect is found to be due to the lower Reynolds
number of the flow over the scaled foils. The lower Reynolds number results in higher
drag and lower lift coefficients for hydrofoils compared with those achieved at full
scale. This effect can only be partially corrected for in the scaling procedure using
the available theoretical scaling methods.
Presently available theoretical methods commonly used for the design of conventional
ships were found to be ill adapted for modeling the complex hydrodynamics
of hydrofoil-assisted catamarans and required further development. Vortex lattice
theory was chosen to model the flow around hydrofoil-assisted catamarans as vortex
theory models the flow around lifting surfaces in the most natural way. The commercial
code AUTOWING is further developed and generalized to be able to model the
complex hull-hydrofoil interactions that change with speed. The method is shown to
make good predictions of all hydrodynamic quantities with accuracies at least as good
as that achievable through model testing and therefore fulfills the requirements for a
suitable theoretical design tool.
The developed theoretical and experimental design tools are used to investigate the
design of hydrofoils for hydrofoil-assisted catamarans. It is found that the main parameter
needing consideration in the hydrofoil design is selection of a suitable hydrofoil
lift fraction. A foil lift fraction in the order of 20-30% of the displacement weight
is needed if resistance improvements using hydrofoil assistance are to be obtained
over the hull without foils. It is often more favorable to use higher foil lift fractions
(50%+) as the resistance improvements are better, although careful attention should
then be given to directional and pitch-heave instabilities. The Hysuwac hydrofoil
system patented by the University of Stellenbosch is found to be hydrodynamically
optimal for most hullforms.
The hullform and in particular the curvature of the aft buttock lines of the hull are
found to have an important influence on the achievable resistance improvements and
behaviour of the hydrofoil-assisted hull at speed. Hull curvature is detrimental to
hydrodynamic performance as the suction pressures resulting from the flow over the
curved hull counter the hydrofoil lift. The hullform best suited to hydrofoil assistance
is found to be one with relatively straight lines and hard chine deep- V sections.
The main conclusion drawn from this study is that hydrofoil-assistance is indeed
suitable for improving the performance and efficiency of catamarans. The design and
optimization of such vessels nevertheless requires careful consideration of the various
resistance components and hull-foil interactions and in particular, how these change
with speed. The evaluation of resistance for design purposes requires some discipline
between theoretical analysis and experimental measurements as the complexity of
the hydrodynamics reduce the accuracies of both. Consideration of these factors
allows hulls and hydrofoils to be designed that are efficient and also free of dynamic
instabilities. / AFRIKAANSE OPSOMMING: Hierdie studie is gerig op die hidrodinamiese ontwerp van hidrovleuel-gesteunde katamarans.
Daar word gefokus op die ontwikkeling van nuwe en geskikte ontwerpmetodes,
asook die toepassing van hierdie metodes om die belangrikste geometriese parameters
van katamaranrompe en hidrovleuel-konfigurasies wat 'n invloed op doeltreffendheid
en werkverrigting het, te identifiseer. As aanloop tot die studie is 'n deeglike begrip
van die onderliggende hidrodinamiese beginsels bekom. Hierdie kennis is toegepas om
nuwe en verbeterde eksperimentele en teoretiese tegnieke te ontwikkel wat nodig is vir
die ontwerp van hidrovleuel-gesteunde katamarans in die belangrike deels-verplasing
en deels-planering spoedbereike.
Daar word getoon dat die bedryfspoedbereik van 'n hidrovleuel-gesteunde katamaran
uit drie onderskeibare hidrodinamiese fases bestaan, naamlik verplasing, oorgang en
planering, en dat verskillende hidrodinamiese beginsels die vaartuig se werkverrigting
in elke fase bepaal. Daar is ook gevind dat die hidrodinamika wesentlik verskil van dié
van konvensionele hoëspoed-vaartuie, hoofsaaklik as gevolg van die interaksie tussen
die romp en die hidrovleuels wat wissel na gelang van die spoed. Hierdie interaksies
moet in ag geneem word gedurende die ontwerpproses en beide eksperimentele en
teoretiese metodes is nuttig om die omvang daarvan te bepaal.
Daar is gevind dat die eksperimentele voorspellings gebaseer op toetse met relatief
klein skaalmodelle van hidrovleuelgesteunde katamarans minder akkuraat is as dié wat
bereik kan word met konvensionele skepe. Dit is omdat al die skaalfoute wat tydens
die toetsing met die model ontstaan, nie gekorrigeer kan word nie. Die belangrikste
skaaleffek is as gevolg van die laer Reynoldsgetal van die vloei oor die afgeskaalde
vleuels. Groter modele Die laer Reynoldsgetal lei tot hoër sleur- en hefkoëffisiënte in
vergelyking met dié vir die volskaal-hidrovleuels. Wanneer die beskikbare teoretiese
metodes gebruik word, kan daar slegs gedeeltelik vir hierdie effek in die skaalprosedure
gekorrigeer word. Daar is ook vasgestel dat die skaaleffekte op die Reynoldsgetal
verminder word wanneer die hidrovleuels baie nabyaan die vrye oppervlakte is. Dit
lei daartoe dat eksperimentele voorspellings van werkverrigting meer akkuraat is vir
die ontwerpe waar die hidrovleuels nie so diep onder die water is nie.
Daar is gevind dat die teoretiese metodes wat tans beskikbaar is en algemeen vir
die ontwerp van konvensionele skepe gebruik word nie die komplekse hidrodinamika
van hidrovleuel-gesteunde katamarans kan modelleer nie. Die werwelroosterteorie is
gekies om die vloei om hidrovleuel-gesteunde katamarans te modelleer aangesien dié
teorie die vloei om hefvlakke op die natuurlikste manier weergee. Die kommersiële
kode AUTOWING is verder ontwikkel en veralgemeen om ook die komplekse spoed-afhanklike interaksies van die romp en hidrovleuel te kan modelleer. Hierdie metode
lewer goeie voorspellings van al die hidrodinamiese maatstawwe met akkuraathede
wat ten minste so goed is soos di wat met modeltoetsing bereik word en voldoen
daarom aan die vereistes vir 'n geskikte teoretiese ontwerpmetode.
Die teoretiese en eksperimentele ontwerpmetode wat ontwikkel is, word gebruik om
die ontwerp van hidrovleuels vir hidrovleuel-gesteunde katamarans te ondersoek. Daar
is gevind dat die belangrikste parameter wat in die hidrovleuel-ontwerp in ag geneem
moet word, die keuse van 'n geskikte hidrovleuelhefverhouding is. Om in rompe met
hidrovleuelsteun verbeterings in die weerstand te kry in vergelyking met rompe sonder
vleuels, is 'n vleuel-hef-verhouding van 20-30 persent van die verplasingsgewig
nodig. Dit is dikwels beter om hoër vleuel-hef-verhoudings (van 50 persent of meer)
te gebruik omdat die verbetering in weerstand dan groter is. Daar moet dan egter
gewaak word teen rigtings- en hei-hef-onstabiliteite. Daar is gevind dat die Hysuwachidrovleuel-
stelsel wat deur die Universiteit van Stellenbosch gepatenteer is, hidrodinamies
optimaal is vir die meeste rompvorms.
Daar is gevind dat die vorm van die romp en veral die kromming van die lyne gevorm
deur vertikale snitte deur die romp (Engels: "aft buttock lines") van die romp 'n
belangrike invloed het op die bereikbare weerstandsverbeterings en die gedrag van die
hidrovleuel-gesteunde romp wat op spoed is. Die kromming van die romp is nadelig
vir die hidrodinamiese werksverrigting aangesien die suigdruk as gevolg van die vloei
oor die gekromde romp die hefkrag van die hidrovleuels teenwerk. Die rompvorm wat
die geskikste is vir hidrovleuel-ondersteuning is 'n romp met relatiewe reguit lyne en
skerp hoekige diep- V seksies.
Die belangrikste gevolgtrekking waartoe tydens die studie gekom is, is dat hidrovleuelondersteuning
wel geskik is vir die verbetering van die werkverrigting en die doeltreffendheid
van katamarans. Die ontwerp en optimering van sodanige vaartuie verg
nogtans die noukeurige oorweging van die verskeie weerstandskomponente en rompvleuel-
interaksies en veral hoe hierdie interaksies verander met spoed. Die evaluering
van die weerstand vir die doeleindes van ontwerp verg dissipline tussen die teoretiese
analise en die eksperimentele metings aangesien die kompleksiteit van die hidrodinamika
die akkuraatheid van die algemeen-gebruikte teoretiese en eksperimentele
metodes vir die hidrodinamiese ontwerp verminder. As hierdie faktore in ag geneem
word, kan rompe en hidrovleuels ontwerp word wat doeltreffend is en ook vry is van
dinamiese onstabiliteite.
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Experimental Investigation Of The Agitation Of Complex FluidsYazicioglu, Ozge 01 July 2006 (has links) (PDF)
In this study, agitation of solutions using different impeller and tank geometry were investigated experimentally in terms of hydrodynamics, macromixing time and aeration characteristics. In the first set of experiments a cylindrical vessel equipped with two types of hydrofoil and a hyperboloid impeller or their combinations were used. Vessel and impeller diameters and water level were 300, 100 and 300 mm, respectively. At the same specific power consumption, 163 W/m3, the so called hydrofoil 1 impeller provided the shortest mixing time at 7.8 s. At the top hydrofoil 1 impeller submergence of 100 mm, the hyperboloid impeller combination of it was the most efficient by a mixing time of 10.0 s at 163 W/m3. Ultrasound Doppler velocimetry and the lightsheet experiments showed that the hydrofoil 1, hydrofoil 2 impellers and the stated impeller combination provided a complete circulation all over the tank.
Macromixing measurements were performed in square vessel for Generation 5 low and high rib and Generation 6 hyperboloid impellers. Vessel length, impeller diameters and water level were 900, 300 and 450 mm, respectively. At the same specific power consumption, 88.4 W/m3, Generation 6 mixer provided the lowest mixing time at 80.5 s.
Aeration experiments were performed in square tank for Generation 5 low rib and Generation 6 hyperboloid impellers equipped with additional blades. With increasing flow number, the differences between the performances at different rotational speeds became smaller for each type of mixer. At similar conditions the transferred oxygen amount of Generation 6 impeller was about 20% better.
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