The Effects of Fluctuating Air Streams on the Output of a Wind Turbine Bnan Al-Qallab * , Hamzeh Duwairi Mechanical Engineering Department, The University of Jordan, Amman 11942, Jordan Corresponding Author Email: Bnanalgallab@gmail.com https://doi.org/10.18280/ejee.210105 ABSTRACT Received: 5 December 2018 Accepted: 1 February 2019 The objective of this work is to model the fluctuating air stream potential of producing wind energy and study different operating parameters of wind turbines, by using conservation principles continuity and momentum, with wind turbine equations. A combination of two numerical methods which include Runge-Kuttha technique with shooting technique were utilized using MATLAB to obtain numerical solutions. It is found that the increasing of corrugated surface amplitudes decreases velocities inside boundary layers and reduce power output compared to those obtained by Blasius or traditional Pet theory. Keywords: boundary layer, electricity production, surface topography, velocity fluctuations, wind energy 1. INTRODUCTION Wind is a form of solar energy, it is formed as a result of the dissimilar heating of the atmosphere by the sun, earth's surface irregularities and rotation of the world. The exploitation of wind energy for power generation functions is becoming step by step more attractive and achieving a substantial share within the electrical power production market globally. When talking about surface roughness, the more the surface is roughened the greater the boundary layer thickness will be and the turbulence level will increase as well. Furthermore, the effect of the roughened surface density is vital, a higher density increases fluctuating level and boundary layer height. The roughness density is the area of the obstacle divided by the surface area. As the density increases so does the roughness of the system, but a point comes where adding new elements will lighten the roughness of the surface, a group of similar height obstacles is less rough than that with different heights [1]. Surface features that have quite a severe impact on velocity profile is the presence of forestry, urbanized structures and topography features such as sinusoidal hills. As the wind moves into such features, the logarithmic profile will be distorted due to the drag forces exerted by a building for example. As would be expected, the mean horizontal wind speed is reduced when the effect of the roughed surface is considered. About the amplitude of the flow wave, for high amplitudes; the presence of separated flow regions must be considered. For these type of flow situations, the complete time dependent Navier-Stokes equations need to be solved. In this manuscript a theoretical model is analyzed and numerically solved by developing a numerical technique to solve governing differential equations. The fluctuations of wind power output as a result of the topography and the presence of obstacles or corrugated surfaces are studied under the effect of fluctuating wind streams. 1.1 Corrugated surfaces hydrodynamics and surface topology Cian examines the possibility of using state of the art measurement and modelling techniques to understand the structure of both forest canopies and the atmosphere above. a full resource assessment for a moderately complex site in the Eastern Scottish Borders region containing 22 wind turbines were performed. A total of 60 sets of results were submitted by 56 organisations located in 17 European countries [2]. Cabezon et al., described the analysis of the elliptical wake model CFD Wake in contradiction of experimental data from wind farm sited in complex terrain Elliptic CFD demonstrating of wakes in complex territory wind farms taking in consider the actuator plate idea is useful. It is presumed that linear superposition of topographic and wind turbine wakes prompts an invalid guess dependent on the consequences of the approval procedure directed in wind cultivate situated in complex landscape [3]. István et al., studied the factors touching wind-energy potential in low settled urban environments. The take a look at interval is that the transition between summer and winter, as a secondary wind most period. Extrapolation to higher levels is feasible by shaping the Hellmann exponent. The outcomes were contrasted to the surface cover of the encompassing space furthermore on the literary alpha values [4]. Sengupta obtained a numerical solution for fully developed turbulent flow over small amplitude sinusoidal wavy surfaces. The cases considered are for both rigid and flexible surfaces. For the rigid surface case, the numerical solution indicated no drag reduction. On the contrary, the total drag of such a surface is more than the drag of an equivalent flat plate. The predictions are in excellent agreement with recent experimental data for rigid wavy surfaces [5]. 1.2 Wind velocity profiles Cattin et al. performed "Alpine Wind harvest", CFD wind modeling with WindSim for 7 destinations. Approval of the demonstrating results was executed to estimate wind climatologies and by contrasting vertical wind profiles with profiles estimated by SODAR. WindSim is proper for extrapolation of estimations within short distances and extrapolations from sufficiently high estimates of height to European Journal of Electrical Engineering Vol. 21, No. 1, February, 2019, pp. 27-34 Journal homepage: http://iieta.org/Journals/ejee 27