Yuhao Jia¹, Bin Cheng^1,2,*, Xiyang Li^1,2, Hui Zhang^1,2, Yinglong Dong¹

Energy Engineering, Vol.117, No.6, pp. 413-427, 2020, DOI:10.32604/EE.2020.012019

Abstract In order to study the effect of icing on the wind turbine blade tip speed ratio and wind energy utilization coefficient under working conditions, it is important to better understand the growth characteristics of wind turbine blade icing under natural conditions. In this paper, the icing test of the NACA4412 airfoil wind turbine was carried out using the natural low temperature wind turbine icing test system. An evaluation model of icing degree was established, and the influence of wind speed and icing degree on the performance parameters of wind turbines was compared and analyzed. It is shown that icing is… More >

Hao Cheng, Guangsheng Du^*, Meng Zhang, Kun Wang, Wenbin Bai

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.4, pp. 685-698, 2020, DOI:10.32604/fdmp.2020.09673

Abstract The determination of the circulation for wind turbine blades is an important problem in engineering. In the present study, we develop a specific approach to evaluate the integral that represents mathematically the circulation. First the potentialities of the method are assessed using a two-dimensional NACA64_A17 airfoil as a testbed and evaluating the influence of different integration paths and angles of attack on the circulation value. Then the method is applied to blades with different relative heights in order to provide useful reference data to be used for the optimization and reverse design of wind turbine blades. As shown by the… More >

G. Trapani¹, T. Kipouros¹, A. M. Savill¹

CMES-Computer Modeling in Engineering & Sciences, Vol.88, No.2, pp. 107-140, 2012, DOI:10.3970/cmes.2012.088.107

Abstract This paper presents the development and the application of a multi-objective optimization framework for the design of two-dimensional multi-element high-lift airfoils. An innovative and efficient optimization algorithm, namely Multi-Objective Tabu Search (MOTS), has been selected as core of the framework. The flow-field around the multi-element configuration is simulated using the commercial computational fluid dynamics (cfd) suite Ansys cfx. Elements shape and deployment settings have been considered as design variables in the optimization of the Garteur A310 airfoil, as presented here. A validation and verification process of the cfd simulation for the Garteur airfoil is performed using available wind tunnel data.… 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 airfoil surface. The… More >

D.N. Srinath¹, Sanjay Mittal¹, Veera Manek²

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.2, pp. 169-190, 2009, DOI:10.3970/cmes.2009.051.169

Abstract A continuous adjoint method is formulated and implemented for the multi-point shape optimization of airfoils at low Re. The airfoil shape is parametrized with a non-uniform rational B-Spline (NURBS). Optimization studies are carried out for two different objective functions. The first involves an inverse function on the lift coefficient over a range of Re. The objective is to determine a shape that results in a lift coefficient of 0.4 at three values of Re: 10, 100 and 500. The second objective involves a direct function on the lift coefficient over a range of angles of attack,a. The lift coefficient is… 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 >

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 model is applied to the… More >

J.M.C.Pereira¹, N.A.R.Maia¹, J.C.F.Pereira¹

CMES-Computer Modeling in Engineering & Sciences, Vol.49, No.2, pp. 113-142, 2009, DOI:10.3970/cmes.2009.049.113

Abstract We present a 2D incompressible Navier-Stokes numerical simulation of a virtual model of an elliptic, or flat plate, foil in hovering flight configuration. Computations obtained with a general purpose solver were validated against reference data on forward flapping flight, normal or dragonfly hovering. The moving mesh technique allows airfoil translation and angular mesh movement accompaining the airfoil stroke motion. Close to the ground the mesh deforms to occupy the narrow computational domain formed between the airfoil and the ground. Computations have been carried out for some parameters, including the distances h between the foil center and the surface, h/c =… 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 in good agreement with the… More >

Rosario M. A. Marretta¹, Giovanni Lombardi², Roberto Antinoro¹

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.1, pp. 73-84, 2003, DOI:10.3970/cmes.2003.004.073

Abstract An approach based on Lighthill's transpiration velocity is explored and proposed for a new design criterion for airfoils in unsteady and viscous flows. This criterion confines its methodologies to the close proximity of the laminar and turbulent boundary layer and it shows good efficiency in predicting and calculating the wake evolution regions in a wide range of operating unsteady parameters. Also, the criterion is capable of predicting low Mach number, attached flow-fields as accurately as the full Navier-Stokes solutions when the massive flow separation is avoided. The agreement of the present results with those empirically and theoretically determined is very… More >