D.M.S. Albuquerque¹, J.M.C. Pereira¹, J.C.F. Pereira^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.72, No.4, pp. 337-366, 2011, DOI:10.3970/cmes.2011.072.337

Abstract A numerical study of fluid-structure interaction is presented for the analysis of viscous flow over a resonant membrane airfoil in hovering flight. A flexible membrane moving with a prescribed stroke period was naturally excited to enter into 1st, 2nd and 3rd mode of vibration according to the selected membrane tension. The Navier-Stokes equations were discretized on a moving body unstructured grid using the finite volume method. The instantaneous membrane position was predicted by the 1D unsteady membrane equation with input from the acting fluid flow forces. Following initial validation against reported rigid airfoils predictions, the… More >

Anant Diwakar¹, D. N.Srinath¹, Sanjay Mittal¹

CMES-Computer Modeling in Engineering & Sciences, Vol.69, No.1, pp. 61-90, 2010, DOI:10.3970/cmes.2010.069.061

Abstract Aerodynamic shape optimization of airfoils is carried out for two values of Reynolds numbers: 10³ and 10⁴, for an angle of attack of 5^o. The objective functions used are (a) maximization of lift (b) minimization of drag and (c) minimization of drag to lift ratio. The surface of the airfoil is parametrized by a 4^th order non-uniform rational B-Spline (NURBS) curve with 61 control points. Unlike the efforts in the past, the relatively large number of control points used in this study offer a rich design shape with the possibility of local bumps and valleys on the… More >

R. Mestiri¹, R.Hadaji¹, S. Ben Nasrallah¹

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.4, pp. 409-418, 2010, DOI:10.3970/fdmp.2010.006.409

Abstract The electroaerodynamic actuator or plasma actuator uses the characteristics of the non-thermal surface plasmas. These plasmas are created in atmospheric pressure by a DC electrical corona discharge at the surface of a dielectric material. The two electrodes are two conductive parallel wires. The applied voltage is of several kilovolts. The corona discharge creates a tangential electric wind that can modify the boundary layer flow properties. In this paper, we present the results found for two geometric configurations: the flat plate and the cylinder. In order to study the discharge specificity, we have found the current- More >

Sujoy Mukherjee¹, Ranjan Ganguli^1,2

CMC-Computers, Materials & Continua, Vol.19, No.2, pp. 105-134, 2010, DOI:10.3970/cmc.2010.019.105

Abstract In this study, variational principle is used for dynamic modeling of an Ionic Polymer Metal Composite (IPMC) flapping wing. The IPMC is an Electro-active Polymer (EAP) which is emerging as a useful smart material for `artificial muscle' applications. Dynamic characteristics of IPMC flapping wings having the same size as the actual wings of three different dragonfly species Aeshna Multicolor, Anax Parthenope Julius and Sympetrum Frequens are analyzed using numerical simulations. An unsteady aerodynamic model is used to obtain the aerodynamic forces. A comparative study of the performances of three IPMC flapping wings is conducted. Among More >

Yangkyun kim¹, Sungcho Kim², Jongwook Choi², Jeong Soo Kim²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.11, No.4, pp. 123-124, 2009, DOI:10.3970/icces.2009.011.123

Abstract This paper analyzes computationally the flow field for the full geometry model of a commercial passenger airplane, Boeing747-400. The geometric dimension of an airplane was acquired by means of the reverse engineering technique adopting the photo scanning measurement. The steady three-dimensional viscous compressible flow field was calculated when the airplane cruises under side flow. The basic computational conditions were considered as the same to those of Boeing 747-400's cruising state, i.e., the atmospheric condition at 13 km above the sea level and Mach number of 0.85. The boundary conditions are the same that the freestream… More >

Tao Cui¹, Wenhao Liao¹ and Daren Yu ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.3, pp. 273-294, 2009, DOI:10.3970/cmes.2009.045.273

Abstract Aerodynamic hysteresis is of practical importance for the flying airfoils. Motivated by the problem of global description on the hysteresis behaviors, this paper proposes a topological approach to analyze and model the hysteresis behaviors exhibited in the airfoil flow from a viewpoint of dynamic system theory. The approach is based on the topological invariant rules of singular points under topological mapping. It is able to theoretically explain such discontinuous hysteresis phenomena, and make consistent and accurate predictions of the hysteresis behaviors in the airfoil flow. The model results have shown that the present model is More >

M. Trikha¹, S. Gopalakrishnan², D. Roy Mahapatra^2,1, R. Pandiyan¹

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.2, pp. 97-140, 2009, DOI:10.3970/cmes.2009.045.097

Abstract A mechanics based linear analysis of the problem of dynamic instabilities in slender space launch vehicles is undertaken. The flexible body dynamics of the moving vehicle is studied in an inertial frame of reference, including velocity induced curvature effects, which have not been considered so far in the published literature. Coupling among the rigid-body modes, the longitudinal vibrational modes and the transverse vibrational modes due to asymmetric lifting-body cross-section are considered. The model also incorporates the effects of aerodynamic forces and the propulsive thrust of the vehicle. The effects of the coupling between the combustion… More >

Seawook Lee¹, Leesang Cho², Jin-Soo Cho³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.3, pp. 113-122, 2008, DOI:10.3970/icces.2008.007.113

Abstract Computational methods based on the solution of the flow model are widely used for the analysis of low-speed, inviscid, attached-flow problems. Most of such methods are based on the implementation of the internal Dirichlet boundary condition. In this paper, the time-domain panel method uses the piecewise constant source and doublet singularities. The present method utilizes the time-stepping loop to simulate the unsteady motion of the rotary wing blade for the KHP. The wake geometry is calculated as part of the solution with no special treatment. To validate the results of aerodynamic characteristics, the typical blade More >

T. Kipouros¹, D.M. Jaeggi², W.N. Dawes³, G.T. Parks²,A.M. Savill¹, P.J. Clarkson²

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.1, pp. 1-44, 2008, DOI:10.3970/cmes.2008.037.001

Abstract An approach to support the computational aerodynamic design process is presented and demonstrated through the application of a novel multi-objective variant of the Tabu Search optimization algorithm for continuous problems to the aerodynamic design optimization of turbomachinery blades. The aim is to improve the performance of a specific stage and ultimately of the whole engine. The integrated system developed for this purpose is described. This combines the optimizer with an existing geometry parameterization scheme and a well-established CFD package. The system's performance is illustrated through case studies -- one two-dimensional, one three-dimensional -- in which… More >

G. Veble^1,2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.3, pp. 243-260, 2008, DOI:10.3970/cmes.2008.036.243

Abstract A simple cost function is proposed that depends on the inviscid pressure distribution around an airfoil and that, when minimized, results in airfoils that promote laminar flow. Additional constraints specify the design point of the airfoil. The method allows for straightforward inclusion of multiple design points. The resulting airfoils are quantitatively similar to those already successfully used in practice. More >