Aerospace Science and Technology
Ahmad Sharafi
Volume 14, Issue 2 , October 2021, , Pages 52-65
Abstract
In the present study, the aerodynamic performance of the ducted fan is investigated using the surface vorticity method and the lifting line theory. In previous research, to consider the effects of the duct, most of the parameters derived from empirical tests or computational fluid dynamics. Our goal ...
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In the present study, the aerodynamic performance of the ducted fan is investigated using the surface vorticity method and the lifting line theory. In previous research, to consider the effects of the duct, most of the parameters derived from empirical tests or computational fluid dynamics. Our goal is to present a new method for considering the effects of the duct on the fan enclosed in a duct. In this method, the lift and drag coefficients are only input parameters. The present method requires considerably less computational time than CFD methods. Also, the aerodynamic optimization of fan blades geometry has been carried out using particle swarm optimization method (PSO) to achieve the optimum blade geometry and the maximum output power. The results of this method are in excellent agreement with experimental data in references. By optimizing the geometry of the blade, the output power of ducted fan increased 10 percentage in comparison to ducted fan with old blade geometry.
Hassan Isvand; Ahmad Sharafi; Ali Salmaninejad
Volume 12, Issue 1 , March 2019, , Pages 1-14
Abstract
In this study, the behavior of a subject consisting of a cylinder with 4 plates perpendicular to it with a rotational degree of freedom under airflow both through the numerical approach, known as improved discrete vortex and experimental approach were investigated. The experimental and numerical results ...
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In this study, the behavior of a subject consisting of a cylinder with 4 plates perpendicular to it with a rotational degree of freedom under airflow both through the numerical approach, known as improved discrete vortex and experimental approach were investigated. The experimental and numerical results have shown that oscillating regime occurs in low velocity and length. This movement is vibrations with irregular range around an equilibrium angle of 45 degree. In oscillating motion regime, it is seen that after releasing the object in free flow, a high torque force, due to the flow’s acceleration from the model, is induced to the plates and makes a big angular change, but after a while, the range of oscillation around the equilibrium angle of 45 degree decreases. The probability of rotational motion regime in length ratio of one and velocity of 13 m/sec in initial angle of attack is low. However, the experimental and numerical results have indicated that still in high initial angle of attack around 45 degree, owing to the induced decreased torque to plates, there exists an oscillating movement. Rotational regime in length ratio of 3 and free flow velocity 13 m/sec in all initial angle of attack is observed. In addition, rotational regime appears in all initial angle of attack with the length ratio of 4 and different free flow velocities because of increase in the area of plates.
