A Prescribed-Wake Vortex Lattice Method for Preliminary Design of Co-Axial, Dual-Rotor Wind Turbines

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Aaron Rosenberg ◽  
Anupam Sharma
Keyword(s):  
Wind Turbines ◽  
Vortex Lattice ◽  
Navier Stokes ◽  
Wake Vortex ◽  
Preliminary Design ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Trailing Vortices ◽  
Computational Fluid Dynamics Cfd ◽  
Reynolds Averaged Navier Stokes

This paper extends the prescribed-wake vortex lattice method (VLM) to perform aerodynamic analysis of dual-rotor wind turbines (DRWTs). A DRWT turbine consists of a large, primary rotor placed co-axially behind a smaller, secondary rotor. The additional vortex system introduced by the secondary rotor of a DRWT is modeled while taking into account the singularities that can occur when the trailing vortices from the secondary (upstream) rotor interact with the bound vortices of the main (downstream) rotor. Pseudo-steady assumption is invoked, and averaging over multiple relative rotor positions is performed to account for the primary and secondary rotors operating at different rotational velocities. The VLM solver is first validated against experiments and blade element momentum theory results for a conventional, single-rotor turbine. The solver is then verified for two DRWT designs against results from two computational fluid dynamics (CFD) methods: (1) Reynolds-averaged Navier–Stokes CFD with an actuator disk representation of the turbine rotors and (2) large-eddy simulations with an actuator line model. Radial distributions of sectional torque force and angle of attack show reasonable agreement between the three methods. Results of parametric sweeps performed using VLM agree qualitatively with the Reynolds-averaged Navier–Stokes (RANS) CFD results demonstrating that the proposed VLM can be used to guide preliminary design of DRWTs.

Thruster and FPSO Hull Interaction

2014 ◽  
Author(s):  
Ye Tian ◽  
Spyros A. Kinnas
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Computational Efficiency ◽  
Vortex Lattice ◽  
Numerical Results ◽  
Navier Stokes ◽  
Dynamic Positioning ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Number Of Cells

A hybrid method which couples a Vortex-Lattice Method (VLM) solver and a Reynolds-Averaged Navier-Stokes (RANS) solver is applied to simulate the interaction between a Dynamic Positioning (DP) thruster and an FPSO hull. The hybrid method could significantly reduce the number of cells to fifth of that in a full blown RANS simulation and thus greatly enhance the computational efficiency. The numerical results are first validated with available experimental data, and then used to assess the significance of the thruster/hull interaction in DP systems.

Use of CFD Techniques in the Preliminary Design of Upwind Sails

1999 ◽  
Author(s):  
Patrick Couser ◽  
Norm Deane
Keyword(s):  
South Africa ◽  
Numerical Methods ◽  
Research And Development ◽  
Computational Methods ◽  
Vortex Lattice ◽  
Development Programme ◽  
Preliminary Design ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Water Testing

The results of the 1997 World Titles, held in Kingston, Canada, highlighted that there was considerable scope for improving the upwind performance of the international Mirror Class by making small adjustments, within the tolerances allowed by the class rule, to the sails and underwater foils. This paper describes some aspects of the Australian research and development programme in preparation for the 1999 World Titles to be held in South Africa in April. Computational methods, based on the vortex lattice method, have been used to provide direction and guidance for the on-the-water testing and trialing programme. The use of these theoretical tools has enabled a far wider range of sail, dagger board and rudder parameters to be investigated than would be possible using purely on-the-water testing. The usefulness of well-understood computational and numerical methods in sail and foil design has been demonstrated; it has also been shown that these tools are within the reach of relatively small budget research and development programmes. The proof of the pudding may be at the 1999 International Mirror Class World Titles ... (watch this space)

3D Simulation of a Convergent-Divergent Aero Engine Intake, Using Two Different CFD Methods

2005 ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Geoffrey Guindeuil ◽  
Theodoros Lekas ◽  
Vassilios Pachidis
Keyword(s):  
Vortex Lattice ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Internal Flow ◽  
Navier Stokes ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Aero Engine ◽  
Flow Effects ◽  
Development And Validation

This study refers to the development and validation of a Three Dimensional (3D) Vortex Lattice Method (VLM) to be used for internal flow case studies and more precisely aero-engine intake simulation. It examines the quantitative and qualitative response of the method to a convergent – divergent intake, produced as a surface of revolution of the CFM56-5B2 upper lip geometry. The study was carried out for three different sections namely: Intake outlet, intake throat and intake inlet. Moreover five different settings of Angle Of Attack (AOA) were considered. The VLM was based on an existing code. It was modified to accommodate internal flow effects and match, as closely as possible, the boundary conditions set by the Reynolds Average Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) simulation. In the context of this study, Vortex Lattice-derived average values velocity profiles were compared against RANS CFD results.

Thruster and Hull Interaction

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Ye Tian ◽  
Spyros A. Kinnas
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Computational Efficiency ◽  
Vortex Lattice ◽  
Numerical Results ◽  
Navier Stokes ◽  
Dynamic Positioning ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Number Of Cells

A hybrid method which couples a vortex-lattice method (VLM) solver and a Reynolds-Averaged Navier–Stokes (RANS) solver is applied to simulate the interaction between a dynamic positioning (DP) thruster and a floating production storage and offloading (FPSO) hull. The hybrid method can significantly reduce the number of cells to fifth of that in a full-blown RANS simulation and thus greatly enhance the computational efficiency. The numerical results are first validated with available experimental data, and then used to assess the significance of the thruster/hull interaction in DP systems.

Relaxed-Wake Vortex-Lattice Method Using Distributed Vorticity Elements

2008 ◽  
Vol 45 (2) ◽  
pp. 560-568 ◽  
Author(s):  
Götz Bramesfeld ◽  
Mark D. Maughmer
Keyword(s):  
Vortex Lattice ◽  
Wake Vortex ◽  
Lattice Method ◽  
Vortex Lattice Method

Aero Engine Axi-Symmetric Convergent-Constant Area Intake 3D Simulation Using a Panel Method Approach

2005 ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Geoffrey Guindeuil ◽  
Petros Kotsiopoulos ◽  
Vassilios Pachidis
Keyword(s):  
Three Dimensional ◽  
Internal Flow ◽  
Navier Stokes ◽  
Lattice Method ◽  
Simulation Code ◽  
Lower Lip ◽  
Vortex Lattice Method ◽  
Constant Area ◽  
Computational Fluid Dynamics Cfd ◽  
General Effort

This study has been carried out as a part of a general effort to develope a powerful simulation code, based on the Vortex Lattice Method (VLM), capable of simulating adequately accurate and comparatively fast, internal flow regimes. It utilizes a convergent – (nearly) constant area axi-symmetric intake three dimensional geometry, emerged as a surface of revolution from the CFM56-5B2 lower lip geometry. The study focuses on the three most critical planes, which are the inlet of the intake, the outlet of the diverging section and the outlet of the intake. Moreover, the sensitivity of the simulation on the variation of the Angle Of Attack (AOA) is tested for four different settings equally spaced, ranging from 0 to 20 degrees. The comparison is carried out on both two-dimensional velocity distributions and average values. The VLM simulation code was based on an existing code, which was modified in order to be adapted to the Reynolds Average Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) boundary conditions.

scholarly journals Nonlinear vortex lattice method for stall prediction

2019 ◽  
Vol 304 ◽  
pp. 02006
Author(s):  
Hasier Goitia ◽  
Raúl Llamas
Keyword(s):  
Vortex Lattice ◽  
Design Parameters ◽  
Preliminary Design ◽  
Empirical Methods ◽  
Swept Wing ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Narrow Scope ◽  
Novel Method ◽  
Semi Empirical

The stall behavior of an empennage is a crucial and conditioning factor for its design. Thus, the preliminary design of empennages requires a fast low-order method which reliably computes the stall behavior and which must be sensitive to the design parameters (taper, sweep, dihedral, airfoil, etc.). Handbook or semi-empirical methods typically have a narrow scope and low fidelity, so a more general and unbiased method is desired. This paper presents a nonlinear vortex lattice method (VLM) for the stall prediction of generic fuselage-empennage configurations which is able to compute complete aerodynamic polars up to and beyond stall. The method is a generalized form of the van Dam algorithm, which couples the potential VLM solution with 2.5D viscous data. A novel method for computing 2.5D polars from 2D polars is presented, which extends the traditional infinite swept wing theory to finite wings, relying minimally on empirical data. The method has been compared to CFD and WTT results, showing a satisfactory degree of accuracy for the preliminary design of empennages.

A Hybrid Viscous/Potential Flow Method for the Prediction of the Wetted and Cavitating Performance of Ducted Propellers

2015 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Chan-Hoo Jeon ◽  
Ye Tian
Keyword(s):  
Present Method ◽  
Vortex Lattice ◽  
Navier Stokes ◽  
Propeller Blade ◽  
Lattice Method ◽  
Viscous Potential Flow ◽  
Vortex Lattice Method ◽  
Hybrid Numerical Method ◽  
Effective Wake ◽  
Ducted Propellers

This paper presents the analysis of the performance for various ducted propellers using a hybrid numerical method, which couples a vortex lattice method (VLM) for the analysis of propellers and a Reynolds-Averaged Navier-Stokes solver for the prediction of the viscous fluid flow around the duct. The effects of viscosity on the effective wake and on the performance of the propeller blade, as well as on the predicted duct forces, are assessed. The prediction of the performance for those ducted propellers from the present method is validated against existing experimental data.

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