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 ca

Vertical axis wind turbines (VAWTs) can be suitably installed in urban regions. Although the power performance is essential, the noise generated by a VAWT may influence the living environment. An accurate prediction of power and noise performance is therefore necessary. In the present study, a precise aerodynamic and aeroacoustic performance assessment of a Darrieus VAWT is accomplished with the aim of exploring the effect of solidity parameter using a high-fidelity method. The improved delayed detached eddy simulation (IDDES) and the Ffowcs Williams and Hawkings (FW-H) acoustic analogy approaches have been utilized for predicting flow field and noise level. The simulations were performed in three different solidities at a specific tip spee

In the present research, a new comprehensive model of a flexible articulated flapping wing robot using the bond graph approach is presented. The flapping kinematics of a two-section wing is introduced via the bond graph based approach on a hybrid mechanism providing amplitude and phase characteristics. The aerodynamic quasi-steady approach equipped with stall correlation is utilized according to the reduced flapping frequency and the angle of attack ranges. The local flow velocity and the wing position are calculated in both wing and body coordinates taking into account rotation and translation of the wing different parts. Estimation of the effective angle of attack is performed by calculating the instantaneous torque distribution on both

A scramjet multi-stage open cooling cycle for co-production of electricity and hydrogen is proposed here in which the fuel of the scramjet is used as coolant of the cooling cycle. Energy and exergy analysis of the devised system are conducted to evaluate the performance of the system and the effects of multi-expansion deliberation. In this integrated system, the waste heat of the scramjet cooling cycle drives the power sub-cycle in which a portion of the overall produced power supplies the required electricity of the proton exchange membrane (PEM) electrolyzer for hydrogen production. The results indicated that a four-stage open cooling cycle can be the best scenario in terms of providing more cooling capacity, electricity, and H 2 producti

The aerodynamic performance of offshore floating wind turbines (OFWTs) is more complicated than onshore wind turbines due to 6‐degree of freedom (DOF) motion of the floating platform. In the current study, the aerodynamic analysis of a horizontal‐axis floating offshore wind turbine is performed with the aim of studying the effects of floating platform movement on the aerodynamic characteristics of the turbine in the presence of a pitch angle control system. The National Renewable Energy Laboratory (NREL) 5‐MW offshore wind turbine is selected as the baseline wind turbine. For this sake, the unsteady blade element momentum method with dynamic stall and dynamic inflow models have been employed to obtain the unsteady aerodynamic loads.

in this paper 5 different techniques for improving the performance of a Darius wind turbine have been studied and being compared. two of them are active which are injection and suction. other 3 methods are passive including riblet, cavity and porous region. for the comparison to be logical the geometry, location and depth of the actuators assumed to be approximately equal in different methods. 2D numerical method has been utilized and the turbulence model is K-epsilon. the numerical framework used here is STAR CCM commercial software. In the first step validation has been performed based on experimental data in the original turbine without flow control. The simulation in the nominal tip speed ratio is then presented which shows that how the

In this paper, an integrated and systematic modeling of all components and subsystems of a flapping bird robot is developed using the bond graph method. The wings kinematic is independently implemented with the aim of evaluating lateral movements of the bird and aerodynamic forces are accurately extracted by assuming quasi-steady theory. In the present dynamic model, the aeroelastic bending behavior of flexible wing of the flapping bird is revealed by the bond graph method. In this regard, three elastic bending modes and one rigid motion mode of the wing are added to the model. In the following, the performance evaluation of the flapping bird and parametric study are carried out around important quantities such as frequency, initial inciden

This paper explores the effect of design variables on the objective functions of clipped delta wing with a modified double-wedge airfoil section based on parametric analysis and CFD-based optimization using response surface method. This type of wing is used in air-launch-to-orbit vehicles. The thickness, wing-span, tip chord, leading edge radius, front diagonal edge and rear diagonal edge lengths are defined as design variables and aerodynamic efficiency, drag and lift coefficients as objective functions. The analysis was performed at Mach 0.85 and 1.2 and for several angle of attack (AOA). The optimization process is performed by numerical stimulation of the flow around the wing at different Mach numbers and AOAs for the deformed geometry

In this study, an unsteady aerodynamic simulation is performed to realize the influences of platform surge motion on the aerodynamic performance of a high capacity offshore floating wind turbine. A dynamic model with pitch angle control system is utilized to propose a more realistic model of wind turbine and also achieve the rated condition of the rotor. The transient effect of platform surge motion on power coefficient, thrust coefficient and blade pitch angle also is investigated. The 5 MW NREL wind turbine is selected for the simulations. The unsteady aerodynamic model contains unsteady blade element momentum method, dynamic stall and dynamic inflow models. The in-home aerodynamic code and the control system model are implemented in MATL

The focus of the present paper is the parametric dynamic study of a flexible bird-like flapping-wing micro-air vehicle (FMAV). A model of a flapping-wing MAV, containing main body, flapping mechanism, flexible wings, and propulsion system consisting of battery, DC motor, and gear box using the bond graph method is presented and then the governing equations of motion from the conceptual model is derived. Moreover, the simulation is carried out in the simulation software 20-sim. The sensitivity analysis of the flapping-wing performance to various mechanical and electrical parameters is done. In this regard, it is conducted to investigate the effect of wing flexibility, relocation of the force point of action, motor initial iner

The aim of the present study is to investigate the accuracy of two different dynamic stall approaches for windturbine airfoils. The first approach is the semi-empirical Leishman-Beddoes model (LB), and the second is the computational fluid dynamic (CFD) results. National Renewable-Energy Laboratory (NREL) S series airfoils are used, and the simulations are performed in Re= 106. For both approaches, aerodynamic coefficients are represented and compared to experimental data. Validation data refer to Ohio State University (OSU) experiments, which are for pitch oscillation. Results show that the accuracy of the LB and CFD methods is dependent on mean angle of attack, reduced frequency and the phase of motion. The semi-empirical model has approp

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 motion