saeed karimian aliabadi

The INVELOX system is an innovative approach that offers improved energy absorption efficiency from wind flow and reduced costs by utilizing smaller wind turbines. This research focuses on investigating the steady-state performance of one, two, or three wind turbines arranged within the venturi section of the system. A comprehensive modeling approach using an improved Blade Element Momentum (BEM) theory is proposed and implemented as a MATLAB code. The code incorporates Prandtl's tip and hub loss factors, as well as turbulent wake corrections. The accuracy of the code is validated against experimental and numerical data. The results demonstrate that in a three-rotor tandem configuration in the INVELOX system, the power extracted from the second and third turbines is 0.54 and 0.24 times the power of the first turbine, respectively. Furthermore, for a two-turbine arrangement in the venturi section, the total power extracted from the system is 53.9% higher than that of a single turbine layout. In the case of a three-turbine configuration, the total power increases up to 1.78 times compared to a single turbine. The proposed model is suitable for geometric optimization and parameter studies. The system's performance is evaluated in terms of tip speed ratio, and the effects of different correction models are analyzed, including the local changes in forces and moments.

This review paper examines the aerodynamic simulation methods of helicopter rotor. First, the classification of the researches carried out in the field of helicopter rotor blade geometry and the field related to each one has been briefly explained. In the following, the material used in helicopter rotor blades is evaluated. Then, considering the emergence of computers and their ability to analyze since the 1970s, the important researches conducted from this date until 2023 have been examined. With the conducted investigations, it can be seen that with the change of materials used in making blades from metal to composite, and as a result of better malleability and more freedom of action in making various shapes, there has been an increasing interest in improving blade geometry among helicopter manufacturing companies and researchers. This confirms the need to improve helicopter rotor simulation methods. At first, these methods were used only for the purpose of analyzing and evaluating the performance of rotors, but with the advancement of computers and commercial software, these simulations were moved towards optimization processes.

In this paper, we present a numerical simulation for integrating active load control using corona discharge-based plasma actuators on the trailing edge of a wind turbine blade. Eulerian simulation is done on a 660 kW wind turbine blade with NACA 0012 profile. The electrohydrodynamic incompressible flow created between two electrodes using the combination of the EHDFoam solver with the BoyantPimpleFoam solver is carried out in the free and open-access OpenFOAM software. The results have been validated using numerical and experimental work. The effects of environmental parameters such as temperature, relative humidity and environmental pressure on the corona discharge process have been investigated. The results of this research showed that with the increase in temperature, humidity and pressure, the discharge process is decreased. The results show a 62% and 35% decrease in the average transfer momentum with an increase in relative humidity and temperature, respectively.

Today, many countries are trying to reduce their dependence on fossil fuels and acquire the energy they need through renewable energy such as wind energy. On the other hand, the design and analysis of wind turbines is suitable for more energy one of the challenges of engineers. Therefore, in this study, momentum models, which is one of the basic methods in the aerodynamics modeling of the vertical axis wind turbine, are examined. These methods are based on the theory of the momentum (actuator disc) and are widely used to evaluate the performance of vertical axis wind turbines. Also it has been attempted to collect basic fair models for designing and analyzing the performance of these turbines. The following are the three models of the stream tubes: the SST model, the MST model, and the dual actuator MST or the same DMST. Each of these models has the advantages and disadvantages that are fully discussed in this research.

The use of urban and rural scale wind turbines that in addition to generating power can play the role of old wind turbines in arid areas will be very attractive. In this research it has been tried to first evaluate the wind energy potential in Zahedan city and then to evaluate a sample of vertical axis wind turbine. First, a three-dimensional semi-analytic code based on the DMST method was developed, the validation of which was studied and presented. Using this tool, the performance of the turbine in terms of power and ventilation has been investigated and in the results of this parametric study, the effect of the cone angle on the power and ventilation coefficient has been explained in detail. Based on the results of this study, it can be seen that increasing the cone angle to 20 degrees, although it reduces the power of the turbine, but does not have a significant effect on the power coefficient and at the same time causes a ventilation coefficient of about 1.6 percent. It was also observed that at a conical angle of 10 degrees and at the working point of the turbine, the output power will be 30 kW and the ventilation flow will be 30,000 m^3⁄h.

In this research, the internal flow of open-end pressure-swirl atomizer, which has many applications in gas turbine engines and space propulsion, is investigated numerically. A multi-phase fluid volume model is used to simulate the internal flow of the atomizer. Also, due to the nature of the rotational flow inside the atomizer, the RNG k-ε turbulence model was used. Structured mesh has been used to achieve better results. In this research, spray parameters such as liquid film thickness, spray cone angle, discharge coefficient and velocity and pressure distribution contours have been studied. Simulation of an open-end atomizer with an L⁄D = 5 ratio, as well as the use of a structured mesh and the inclusion of kerosene fuel to create conditions close to the operation of a gas turbine, are among the things that differentiate the present study from other studies. The results also show that at a pressure of 0.5 MPa, the time required to reach the fuel in the atomizer used is less than 1.5 milliseconds and the failure of the to spray cone and turn into larger droplets can be observed. The spray angle and discharge coefficient for the studied atomizer were 74.8 and 0.17, respectively.

In previous studies on the INVELOX system, the effect of turbine blades embedded in the venturi section has not accounted. In addition, the design and modeling of an optimal wind turbine in accordance with the geometry and aerodynamic conditions of the venturi section has not been done. Therefore, in this paper, using the BEM (blade element momentum) theory and considering Prandtl's tip and hub loss factors, and also turbulent wake correction, a semi-analytical code has been developed. First of all, an optimal wind turbine according to geometrical and operational assumed INVELOX system is designed. In the continuation, modeling and performance study of geometric parameters of the designed wind turbine has been done. The validation results show that the developed code agrees accurately with the previous experimental, numerical, and analytical results, and therefore the geometry designed for the blades will be reliable. In addition, the application of Glauert and Burton's corrections has been evaluated in this manuscript. Based on the research findings, it is concluded that under the same conditions, Burton's correction yields more conservative results than Glauert's correction. So that assuming 3 blades and a wind speed of 11 meters per second m/s and taking into account Prandtl's tip and hub loss factor, the maximum power coefficient and blade tip speed corresponding to Burton's correction are 0.335 and 7.178, respectively, and corresponding to Glauert's correction, are 0.385 and 7.825, respectively. The provided substrate can be used to optimize the blade shape and structure of the INVELOX wind turbine system.

In this research the aerodynamic performance of a discrete wing capable of morphing, has been studied based on the numerical techniques. In the proposed wing the chord-wise strips have been implemented to resemble a bird wing’s feathers. The morphing mechanism composed of changing the wrist angle which is equal to the partially sweep angle and the wing planform area. Here it is shown that by utilizing this proposed simple mechanism, the MAV/UAV could enhance its aerodynamic performance and also produce control power in the longitudinal and lateral maneuvers. Firstly, the benchmark geometry and a suitable numerical scheme are introduced. The results are then compared and validated against the reference available data. Consequently, the parametric study is performed by selecting the morphing wing tip sweep angle and the angle of attack as the variables and the force coefficients and efficiency as the performance indices. This kind of morphing could make the efficiency increase, up to 13 percent. Flow simulations around the wing are depicted for various morphing angles and for two angles of attack, both in the steady and unsteady manner. The results are also compared and analyzed. Based on the current research, one may continue to estimate the control forces produced by this simple mechanism to expedite the longitudinal and lateral maneuvers in a specified MAV.

The aim of this research is to redesign and optimize of a rotor blade in small size wind turbine. The objective of such optimization is both running time and power coefficient. The aerodynamic modeling of rotor has been presented based on blade element momentum theory. The output parameters have been calculated subsequently. For validation the model is being compared with NREL phase VI turbine data. The technique of optimization is NSGA-II which is appropriately cope with multi objective problems. Variable are assumed to be pitch or twist angle and chord length and the cost function or performance index is composed of drive time and power. The max tip speed ratio and the bounds of variables are constraints. Based on the Pareto diagram it can be deduced by increasing the power, time would be influenced and degraded. It is recommended 3 points and all the characteristics are being drawn for each one. By choosing the compromise point, it is achievable to enhance the power coefficient by approximately 9 percent and to reduce the time of reaching nominal speed by approximately 10 percent

In this paper, the effects of a floating platform rotational motion on performance of an offshore wind turbine are investigated. For this sake, the unsteady blade element momentum method is used as the aerodynamic modelling tool. The proposed model has been validated based on data available for the reference turbine in the ground or fixed platform. To estimate the pitch angle as the control parameter in the power adjusting system, the PI controller is being utilized. The rotation of floating platform including three main angular motion as pitch, roll and yaw have been studied which are approximated by a sinusoidal function. Results showed that among rotational motions, the effect of pitch motion is more considerable than roll and yaw motions. In case of pitching motion input, reduction of mean power coefficient for tip speed ratios less that 7 is expected. For high tip speed ratios more than a critical TSR, the trend is reverse with respect to fixed-platform case. Magnitude of change in the power coefficient however depends on several parameters which is explained more in the paper. The same but degraded trend also occurs in the case of roll and yaw disturbances. Moreover, the mean value of blade pitch angle which is an index of control effort is being increased.

In this paper, the Semi-Empirical and numerical methods that can be used to investigate the effects of dynamic stall are compared with each other, and the capabilities of the methods are studied. The experimental measurements have been used in order to compare the methods. The Semi-Empirical Leishman-Beddoes (L-B), Snel and ONERA methods have been used, and the finite volume method was being used for numerical simulations. The lift coefficient was being calculated by all the methods at various conditions, and the drag coefficient had been computed by the numerical and Leishman-Beddoes methods. The parameters that have been used in order to compare the methods, are the maximum lift coefficient value, the angle of attack of the largest lift coefficient, the error at upstroke phase and the error at down stroke phase. The results show among the semi-empirical models; the L-B method has the highest precision to predict the lift coefficient, and although the numerical method can investigate the flow with more details, but the error percentage at the down stroke phase is higher than expectations. The results from the drag coefficient modeling show that the numerical method can predict this coefficient better than the L-B method. The results also can help other researchers to select the best dynamic stall model in order to investigate the wind-turbine aerodynamics.

In this paper, the importance of accurate estimation of the aerodynamic performance of delta wing has been mentioned. Some available and conventional methods of estimating the aerodynamic coefficients composed of CFD methods and industrial and commercial software have been selected and for comparison, a wing similar to delta wing mounted on Pegasus Air-launch-to-orbit missile as a template is being selected. The reason for this selection, mainly is the lack of wind tunnel in design process and flying in a wide range of flow regimes. As many parameters may be utilized in design process such as the aerodynamic force and moment coefficients, stability derivatives, heat transfer coefficient and the structural loading parameters are being required. In this study, the accuracy of the results of different methods in estimating the force and moment coefficients, as the most significant quantities for performance analysis, at any flow regime has been checked and the suitable method has been introduced in terms of the flight condition. With respect to available parallel processing system, different CFD methods are compared together. Then validity of solution of Reynolds-averaged equations (RANS) and Euler method have been evaluated based on the comparison by DES solutions. Therefore, the valid intervals of the subsequent methods have been presented. Results are indicating the advantage of computational methods to industrial and semi-empirical software. Semi-empirical code and industrial software are shown satisfactory for computation in the linear range i.e. the small angle of attacks.