Prototype Support Structure for Seabed Mounted Tidal Current Turbines

2005 ◽  
Vol 219 (4) ◽  
pp. 173-183 ◽  
Author(s):  
A Owen ◽  
I G Bryden
Keyword(s):  
Steel Structure ◽  
Field Measurements ◽  
Model Fit ◽  
Scale Model ◽  
Conceptual Basis ◽  
Simple Mathematical Model ◽  
Low Aspect Ratio ◽  
Induced Drag ◽  
Tidal Turbine ◽  
Drag And Lift

This paper introduces the patented concept of the Sea Snail, a pin-jointed tubular steel structure carrying an array of symmetrical section hydrofoils, which is used as a means of fixing a tidal turbine, or other devices, to the seabed. The concept is evaluated as a simple mathematical model, tested as a one-eighth-scale model and subsequently developed into a 21 t model fit for sea trials. Pressure differences created by the flow over the upper and lower surfaces of the hydrofoils generate negative lift, or downforce, which is communicated to the supporting structure. The effects of induced drag on low-aspect-ratio hydrofoils are discussed. This paper gives an overview of the evaluative techniques employed in the Sea Snail's concept and design. The need for the device is outlined and its conceptual basis discussed. In particular, the response of a hydrofoil to increasing angles of attack within a steady flow is examined. Field measurements of the drag and lift forces applied to an NACA0013 section hydrofoil is presented in the context of the Sea Snail. The fundamental design criteria are discussed and the Sea Snail's ability to match these criteria is demonstrated.

Modeling IACC Sail Forces by Combining Measurements with CFD

1993 ◽  
Author(s):  
Jerome H. Milgram ◽  
Donald B. Peters ◽  
D. Noah Eckhouse
Keyword(s):  
Scale Model ◽  
Force Model ◽  
Actual Performance ◽  
Force Coefficients ◽  
Prediction Program ◽  
Induced Drag ◽  
Load Cells ◽  
Velocity Prediction ◽  
America’S Cup ◽  
Parasitic Components

A sailing dynamometer with a 42% scale model of an International America's Cup Class rig is used to measure sail forces and moments in actual sailing conditions. The sailing dynamometer is a 35-foot boat containing an internal frame connected to the hull by six load cells configured to measure all the forces and moments between the frame and the hull. All sailing rig components are attached to the frame, so that the sail forces are measured. Sail shapes in use are determined by computer-interfaced video. Computational fluid dynamics performed on the measured shapes provides the induced drag. This allows the measured drag to be decomposed into induced and form-and-parasitic components, which is necessary for generating a mathematical sail force model for a velocity prediction program (VPP). It is shown that VPP results using these new sail force coefficients are in better agreement with actual performance than are VPP results based on traditional sail force coefficients.

Experimental investigation on the structures and induced drag of wingtip vortices for different wingtip configurations

2020 ◽  
pp. 095441002094791
Author(s):  
Ze-Peng Cheng ◽  
Yang Xiang ◽  
Hong Liu
Keyword(s):  
Growth Rate ◽  
Form Factor ◽  
Drag Coefficient ◽  
Particle Image ◽  
Vortex Center ◽  
Streamwise Location ◽  
Induced Drag ◽  
Wingtip Vortex ◽  
Image Velocimetry ◽  
Drag And Lift

As an effective method to reduce induced drag and the risk of wake encounter, the winglet has been an essential device and developed into diverse configurations. However, the structures and induced drag, as well as wandering features of the wingtip vortices ( WTVs) generated by these diverse winglet configurations are not well understood. Thus, the WTVs generated by four typical wingtip configurations, namely the rectangular wing with blended/raked/split winglet and without winglet (Model BL/ RA/ SP/NO for short), are investigated in this paper using particle image velocimetry technology. Comparing with an isolated primary wingtip vortex generated by Model NO, multiple vortices are twisted coherently after installing the winglets. In addition, the circulation evolution of WTVs demonstrates that the circulation for Model SP is the largest, while Model RA is the smallest. By tracking the instantaneous vortex center, the vortex wandering behavior is observed. The growth rate of wandering amplitude along with the streamwise location from the quickest to the slowest corresponds to Model SP, Model NO, Model BL, Model RA in sequence, implying that the WTVs generated by model SP exhibit the quickest mitigation. Considering that the induced drag scales as the lift to power 2, the induced drag and lift are estimated based on the wake integration method, and then the form factor λ, defined by [Formula: see text], is calculated to evaluate the aerodynamic performance. Comparing with the result of Model NO, the form factor decreases by 7.99%, 4.80%, and 2.60% for Model RA, Model BL, Model SP, respectively. In sum, Model RA and BL have a smaller induced drag coefficient but decay slower; while Model SP has a larger induced drag coefficient but decays quicker. An important implication of these results is that reducing the strength of WTVs and increasing the growth rate of vortex wandering amplitude can be the mutual requirements for designing new winglets.

Numerical Study in Wing Tip Vortex for a Modified Commercial Boeing Aircraft

2008 ◽  
Author(s):  
Ricardo Hernandez-Rivera ◽  
Abel Hernandez-Guerrero ◽  
Cuauhtemoc Rubio-Arana ◽  
Raul Lesso-Arroyo
Keyword(s):  
Numerical Study ◽  
Tip Vortex ◽  
Total Drag ◽  
The Core ◽  
Induced Drag ◽  
Wing Tip Vortex ◽  
Drag And Lift ◽  
Wing Tips ◽  
Wing Tip ◽  
Constant Mach Number

Recent studies have shown that the use of winglets in aircrafts wing tips have been able to reduce fuel consumption by reducing the lift-induced drag caused by wing tip vortex. This paper presents a 3-D numerical study to analyze the drag and lift forces, and the behavior of the vortexes generated in the wing tips from a modified commercial Boeing aircraft 767-300/ER. This type of aircraft does not contain winglets to control the wing tip vortex, therefore, the aerodynamic effects were analyzed adding two models of winglets to the wing tip. The first one is the vortex diffuser winglet and the second one is the tip fence winglet. The analyses were made for steady state and compressible flow, for a constant Mach number. The results show that the vortex diffuser winglet gives the best results, reducing the core velocity of the wing tip vortex up to 19%, the total drag force of the aircraft up to 3.6% and it leads to a lift increase of up to 2.4% with respect to the original aircraft without winglets.

scholarly journals Towards a turbulence characterization in tidal energy sites. First results of THYMOTE project

2019 ◽  
Vol 261 ◽  
pp. 05002 ◽  
Author(s):  
Sylvain Guillou ◽  
Jean-François Filipot ◽  
Jérôme Thiébot ◽  
Grégory Germain ◽  
Nicolas Chaplain ◽  
...  
Keyword(s):  
Free Surface ◽  
Numerical Modelling ◽  
Physical Modelling ◽  
Field Measurements ◽  
Tidal Energy ◽  
Turbulence Level ◽  
High Current ◽  
First Results ◽  
Tidal Turbine ◽  
High Turbulence

Tidal turbine will be installed in area with high current and high turbulence level. A characterisation of this last is required. The aim of the project THYMOTE is to characterize and understand the generation of eddies from smaller to several tens of meters. Three technics are used: Numerical modelling, Physical modelling, field measurements. Physical and numerical modelling show clearly the appearance of the eddies close to the bottom in presence of dunes or rocks and their motion towards the free surface.

Optimization of CO2 Foam EOR Processes: A Case Study from Lab-scale Model Fit to Field-Scale Development Planning

2019 ◽  
Author(s):  
Mohammad Izadi ◽  
Phuc H. Nguyen ◽  
Hazem Fleifel ◽  
Doris Ortiz Maestre ◽  
Seung I. Kam
Keyword(s):  
Scale Development ◽  
Development Planning ◽  
Model Fit ◽  
Scale Model ◽  
Field Scale ◽  
Co2 Foam ◽  
Eor Processes

scholarly journals Lifting-Line Predictions for Induced Drag and Lift in Ground Effect

2013 ◽  
Vol 50 (4) ◽  
pp. 1226-1233 ◽  
Author(s):  
W. F. Phillips ◽  
D. F. Hunsaker
Keyword(s):  
Ground Effect ◽  
Induced Drag ◽  
Drag And Lift ◽  
Lifting Line

Three-Dimensional Numerical Simulation of the Flow around Two Side-by-Side Cylinders of Different Diameters

2014 ◽  
Vol 721 ◽  
pp. 199-202
Author(s):  
Zhen Xiao Bi ◽  
Zhi Han Zhu
Keyword(s):  
Numerical Simulation ◽  
Flow Direction ◽  
Three Dimensional ◽  
Cross Flow ◽  
Simulation Method ◽  
Scale Model ◽  
Hydrodynamic Characteristics ◽  
Eddy Simulation ◽  
Drag And Lift ◽  
Different Diameters

This paper presents the calculation of hydrodynamic characteristics of two side-by-side cylinders of different diameters in three dimensional incompressible uniform cross flow by using Large-eddy simulation method based on dynamical Smagorinsky-Lilly sub-grid scale model. Solution of the three dimensional N-S equations were obtained by the finite volume method. The numerical simulation focused on investigating the characteristic of the pressure distribution (drag and lift force), vorticity field and turbulence Re=. Results shows that, the asymmetry of the time –averaged velocity distribution in the flow direction behind the two cylinders is very obvious; the frequency of eddy shedding of the small cylinder is about twice of the large one. The turbulence of cylinders is more obvious.

Multi-scale pulsatile CFD modeling of thrombus transport in a patient-specific LVAD implantation

2017 ◽  
Vol 27 (5) ◽  
pp. 1022-1039 ◽  
Author(s):  
Ray O. Prather ◽  
Alain Kassab ◽  
Marcus William Ni ◽  
Eduardo Divo ◽  
Ricardo Argueta-Morales ◽  
...  
Keyword(s):  
Field Measurements ◽  
Lumped Parameter Model ◽  
Scale Model ◽  
Cfd Modeling ◽  
Patient Specific ◽  
Physiological Data ◽  
Peripheral Vasculature ◽  
Ventricular Assist ◽  
Content Type ◽  
Multi Scale

Purpose Predictive models implemented in medical procedures can potentially bring great benefit to patients and represent a step forward in targeted treatments based on a patient’s physiological condition. It is the purpose of this paper to outline such a model. Design/methodology/approach A multi-scale 0D-3D model based on patient specific geometry combines a 0-dimensional lumped parameter model (LPM) with a 3D computational fluid dynamics (CFD) analysis coupled in time, to obtain physiologically viable flow parameters. Findings A comparison of physiological data gathered from literature with flow-field measurements in this model shows the viability of this method in relation to potential predictions of pathological flows repercussions and candidate treatments. Research limitations/implications A limitation of the model is the absence of compliance in the walls in the CFD fluid domain; however, compliance of the peripheral vasculature is accounted for by the LPM. Currently, an attempt is in progress to extend this multi-scale model to account for the fluid-structure interaction of the ventricular assist device vasculature and hemodynamics. Originality/value This work reports on a predictive pulsatile flow model that can be used to investigate surgical alternatives to reduce strokes in LVADs.

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