جستجوی مقالات مرتبط با کلیدواژه « ضریب برآ » در نشریات گروه « برق »

One approach to improve the aerodynamic performance of airfoils and hydrofoils is inject a small amount of energy to the system (such as fluid injection or suction on the surface), to change the lift and drag. In fact, surface suction and blowing of the fluid can improve the pressure distribution and velocity gradient on the airfoil/hydrofoil surfaces and modify the flow separation point. Therefore, in this study the hydrodynamic behavior of turbulent flows over an airfoil exposed to the injection and suction of fluid in a part of its upper surface is discussed. Firstly, the behavior of the airfoil under one position of the injection or suction and then under two positions of injection or suction are investigated. In this simulation, the FLUENT software is used. The aim of this study is to investigate the effect of the power, the number, the position and the angle of blowing or suction on the hydrodynamic performance of the airfoil. The most important results are the reduction of 10 to 50 percent of the drag and the increase of 5 to 10 percent of the lift (for the blowing) and the reduction of 5 to 30 percent of the drag and the increase of 5 to 10 percent of the lift (for the suction) by considering two positions of injection in comparison to one position.

In recent years, environmental concerns are the greatest challenge in vehicle design. Electric vehicles seem to be a suitable solution to this problem. Therefore, numerous measures have been taken to increase the efficiency, reduce losses, and improve the performance of these vehicles. Aerodynamic characteristics improvement is a key issue that should be considered in vehicle design. In this paper, the effects of improving the aerodynamic characteristics on the electric vehicles are analyzed. For this purpose, installing movable rear spoiler along with a controller and covering the rear wheels have been proposed. In order to evaluate the proposed solutions, their effects on an electric vehicle prototype that has been constructed and developed by the authors have been modeled in MATLAB SIMULINK environment. The flow around the electric vehicle has been studied in ANSYS in order to calculate the drag and lift coefficients. The flow has been numerically solved using the Computational Fluid Dynamics (CFD). The standard k-ε turbulence model has been utilized in this study. The results show that improvement of aerodynamic characteristics in electric vehicles not only increases the stability of the vehicle, but also has a significant impact on the energy storage system, mileage, and the electric motor efficiency.