Modified Unsteady Vortex Lattice Method for Aerodynamics of Flapping Wing Models

2015 ◽  
Author(s):  
Anh Tuan Nguyen ◽  
Jae-Hung Han
Keyword(s):  
Vortex Lattice ◽  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Preliminary Design ◽  
Aerodynamic Forces ◽  
Lattice Method ◽  
Real Motion ◽  
Flapping Motion ◽  
The Real ◽  
Vortex Lattice Method

Motivated by extensive possible applications of flapping-wing micro-air vehicles (MAVs) to various different areas, there has been an increasing amount of research related to this issue. In the stage of preliminary studies, one of the most important tasks is to predict the aerodynamic forces generated by the flapping motion. Studying aerodynamics of insects is an efficient way to approach the preliminary design of flapping-wing MAVs. In this paper, a modified version of an Unsteady Vortex Lattice Method (UVLM) is developed to compute aerodynamic forces appearing in flapping-wing models. A hawkmoth-like wing with kinematics based on the real motion is used for the simulations in this paper.

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)

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.

Design of a Bio-Inspired Spherical Four-Bar Mechanism for Flapping-Wing Micro Air-Vehicle Applications

2008 ◽  
Author(s):  
Matt McDonald ◽  
Sunil K. Agrawal
Keyword(s):  
Three Dimensional ◽  
Micro Air Vehicles ◽  
Aerodynamic Performance ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Wing Motion ◽  
Air Vehicle ◽  
Flapping Mechanism

Design of flapping-wing micro air-vehicles presents many engineering challenges. As observed by biologists, insects and birds exhibit complex three-dimensional wing motions. It is believed that these unique patterns of wing motion create favorable aerodynamic forces that enable these species to fly forward, hover, and execute complex motions. From the perspective of micro air-vehicle applications, extremely lightweight designs that accomplish these motions of the wing, using just a single, or a few actuators, are preferable. This paper presents a method to design a spherical four-bar flapping mechanism that approximates a given spatial flapping motion of a wing, considered to have favorable aerodynamics. A spherical flapping mechanism was then constructed and its aerodynamic performance was compared to the original spatially moving wing using an instrumented robotic flapper with force sensors.

scholarly journals An Integrated Program to Simulate the Multibody Dynamics of Flapping Flight  

2020 ◽  
Vol 31 (1) ◽  
pp. 76-84
Keyword(s):  
Multibody Dynamics ◽  
Vortex Lattice ◽  
Lagrange Equation ◽  
Micro Air Vehicles ◽  
Flapping Flight ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Runge Kutta Method ◽  
Air Vehicle ◽  
Integrated Program

This paper presents an in-house developed program that couples multibody dynamics and aerodynamics codes to simulate flapping flight of insects and micro air vehicles. The multibody dynamics code is built based on the numerical solution of the Lagrange equation, while the extended unsteady vortex-lattice method is employed to develop the aerodynamics code. The solution from the governing equation is obtained by the use of the fourth-order Runge-Kutta method and validated against the simulation results from a commercial software MSC Adams for a micro air vehicle model. In this work, parallel computing techniques are applied while estimating the aerodynamics force to minimize the running time of the program.

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.

Comparison of Tacking and Wearing Performance Between a Japanese Traditional Square Rig and a Chinese Lug Rig

2005 ◽  
Author(s):  
Yutaka Masuyama ◽  
Akira Sakurai ◽  
Toichi Fukas ◽  
Kazunori Aoki
Keyword(s):  
Wind Tunnel ◽  
Vortex Lattice ◽  
Aerodynamic Performance ◽  
Measured Data ◽  
The Other ◽  
Aerodynamic Forces ◽  
Lattice Method ◽  
Wind Tunnel Tests ◽  
Vortex Lattice Method ◽  
Force Variation

Aerodynamic performance of a Japanese traditional square rig, “Bezai-ho”, and a Chinese lug rig, “Shinshi-bo” in Japanese, were studied by means of wind tunnel tests, sea trials and numerical calculations. Sail forces and sail shapes were measured in the wind tunnel tests. A sail dynamometer boat Fujin was employed for the sea trials, by which aerodynamic forces acting on sail, sail shapes, and sailing conditions of the boat can be measured at the same time. Using the measured sail shapes, sail forces are calculated by means of a vortex lattice method. Differences of sail performance of the above mentioned two types of rig were clarified in the wind tunnel tests and sea trials. The calculated sail performance shows good agreements with the measured data in upwind condition. Dynamic sail performance of the two types of rig during tacking and wearing operations was also clarified in the sea trials using the boat Fujin. Details of sail force variation in time during maneuvering can be investigated by the sail dynamometer system. For the “Bezai-ho,” the backward force acting on sail when the boat changes tacks (wind over the bow) was investigated. At this moment, the square sail falls into a “caught aback” situation, which makes the tacking operation difficult. On the other hand, “Shinshi-bo” showed good steady performance similar to that of the modern marconi rig, and good tacking performance. Obtained results of steady and dynamic sail performance in this paper provide useful information for sail trimming and maneuvering of boats equipped with the western square rigs and modern lug rig introduced by H.G. Hasler.

Calculation of the Aerodynamic Forces on Automotive Lifting Surfaces

1985 ◽  
Vol 107 (4) ◽  
pp. 438-443 ◽  
Author(s):  
J. Katz
Keyword(s):  
Steady State ◽  
Vortex Lattice ◽  
Numerical Technique ◽  
Angle Of Attack ◽  
Ground Effect ◽  
Aerodynamic Forces ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Close Proximity ◽  
Lifting Surfaces

A numerical technique was developed to investigate the performance of automotive lifting surfaces in close proximity to ground. The model is based on the Vortex Lattice Method and includes freely-deforming wake elements. The ground effect was simulated by reflection and both steady and unsteady pressures and loads on various wing planforms were considered. Calculated results are presented for wings having both positive and negative incidences, with and without ground effect. Also the transient lift of a wing in a plunging motion was analyzed in ground proximity and at a negative angle of attack. Finally the periodic lift fluctuations on the front winglet of a racing car, due to its suspension oscillations, were calculated and found to exceed approximately twice the steady-state value.

Generalized vortex lattice method for planar supersonic flow

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1230-1233
Author(s):  
Paulo A. O. Soviero ◽  
Hugo B. Resende
Keyword(s):  
Supersonic Flow ◽  
Vortex Lattice ◽  
Lattice Method ◽  
Vortex Lattice Method
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