## 1 Introduction  
In the field of energy production, wind energy is a key issue in order to reduce fossil fuel dependency. In addition, the solar-wind hybrid energy system has become very popular ([PERSON] et al. [1]). Wind energy is an essential resource among the other clean energy production methods. The search for an energy power policy that is local, sustainable, and environmentally friendly, and optimizes resources has become a requirement. Therefore, models that include factors such as emissions reduction, minimization of imported energy, and even social acceptance are proposed in many studies, such as [PERSON] et al. [2] and [PERSON] et al. [3]. Lately research, has been focused on wind turbine blade improvements to optimize rotor dynamic behavior ([PERSON] et al. [4] and [PERSON] et al. [5]). The yearly 9% increase of installed wind energy in Europe in the last fifteen years shows the significance of research in the field of flow control for large wind turbines ([PERSON] et al. [6]). The considerable growth of wind turbine rotor size and weight in the last decade has made it impossible to control as they were controlled 30 years ago. Rotors of 120 meters or even more are now a reality. [PERSON] et al. [7] compiled some of the most important load control techniques that could be used in wind turbines to assure a safe and optimal operation under a variety of atmospheric conditions. The improvements of present wind turbines should be pointed to minimize the fatigue from the wind turbine rotor and other structural components due to changes in wind direction, speed and turbulence, as well as start-stop operations of the wind turbine and, of course, to maximize the energy production. In the last decades, many different flow control devices have been designed and developed (see [PERSON] et al. [8]). Most of them were intended for aeronautical applications ([PERSON] [9]), but also frequently used in turbo machinery (see [PERSON] et al. [10] and [PERSON] et al. [11]). Currently, researchers are working to optimize and introduce this type of devices in horizontal axis wind turbines (HAWT). [PERSON] [12] developed a four layer scheme which allows classifying the different concepts that are part of all flow control devices. In the study of [PERSON] et al. [13], a tangential air jet was used on a vertical axis wind turbine (VAWT) blade to control the separation of the flow and therefore to increase the aerodynamic performance. In addition, the dynamic stall control was investigated by [PERSON] et al. [14] on a S809 airfoil by the implementation of a co-flow jet. Depending on their operating principle, they can be classified as actives or passives (see [PERSON] et al. [15]). Passive control techniques would represent an improvement in the turbine's efficiency and in loads reduction without external energy consumption. Active control techniques need an additional energy source to get the desired effect on the flow and, unlike microtabs and other passive devices, active flow control needs intricate algorithms to get the maximum benefit (see [PERSON] et al. [16] and [PERSON] et al. [17]). [PERSON] et al. [7] made an analysis and discussed fifteen different devices for wind turbine control. Some of them are still being tested on full-scale turbines. The microtabs (MTs) consist of a small tabs situated close to the trailing edge (TE) of an airfoil, which projects perpendicular to the surface of the airfoil a few percent of the chord length \(c\) (usually 1-2%) corresponding to the boundary layer thickness. The potential of MTs was first investigated by [PERSON] et al. [18]. [PERSON] et al. [19] carried out broad study dedicated to the S809 airfoil with MTs. These MTs jets the flow in the boundary layer away from the blade's surface, bringing a recirculation zone behind the tab, as can be observed in Figure 1. The MTs affect the airfoil aerodynamics shifting the point of flow separation and, therefore, providing changes in lift.