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Showing 3 results for Aerodynamic Coefficients
Mojtaba Dehghan Menshadi, Mehdi Eilbeigi, Mehrdad Bazaz Zadeh, Mohammad Ali Vaziry,
Volume 16, Issue 5 (7-2016)
Abstract
The aerodynamic coefficients characteristics over a lambda-shaped flying wing aircraft with 55°-30° leading edge sweep angles have been investigated in a closed circuit low speed wind tunnel. The experiments were conducted at tunnel velocity of 90 m/s, the angles of attack of -6 to 17 and the side-slip angles of -8 to 8 degrees. All forces and moments were measured using an external six-component force balance located below the wind tunnel. The wall corrections were also performed for all test conditions. To improve the aircraft longitudinal stability characteristics, a new model with an increased leading edge sweep angle of 2 degrees were also tested and compared with the original model. A “pitch-up” phenomenon identified to occur at a rather low angle of attack of α=7.7 degrees, although it occurred at the higher angle of attack of α=8.7 degrees for the increased swept angle model which means an increase in useable lift of the aircraft. Moreover, off-surface pressure measurement over the wing surface was conducted to examine the onset and development of the flow separation over the wing surface. The results showed that the flow separation started at the trailing edge crank location and extended to the other parts of the wing, especially the outer wing.
M. Tavalaee Fard , H. Parhizkar , M. Garshasbi ,
Volume 20, Issue 4 (4-2020)
Abstract
The purpose of this paper is to investigate and compare the aerodynamic coefficients obtained from the wind tunnel, numerical solution (Fluent) and engineering software (MD) for a cruise missile. The results are obtained in zero deflection of the control surfaces. For this purpose, the analysis has been carried out on the aerodynamic coefficients of the three Mach numbers: 0.6, 0.75, and 0.85, and various angles of attacks. The results of the numerical solution for calculating the coefficients of the lift, drag, normal and axial forces are respectively with a mean difference of 8.6, 1.7, 8.3 and 8.4 percent, respectively, in comparison with the wind tunnel. The results of the MD software for drag and axial forces are acceptable with an average error of 11% and 20%, respectively. Also, the existence of errors in the MD software, such as taking into account the effects of the air inlet opening only in the axial direction, shows that this method is unreliable in the present study. The results show that there is a great similarity between the behavior of the aerodynamic coefficients changes relative to the angle of attack in all three experimental and numerical methods and the MD software. Also, the pitching moment coefficient variation according to the angle of attack indicates that the trim angle varies from +6 to + 7 degrees.
Mohsen Nazemian Alaei, Mohammad Sadegh Valipour,
Volume 23, Issue 2 (1-2023)
Abstract
Wingsuit flying is one of the most popular flight disciplines in recent decades. In the aviation profession, efficiency and safety are paramount concerns for costume designers. An article in this issue examines how waveform changes to the wing surfaces of a wingsuit model improves aerodynamic performance. In order to increase performance, vortices are produced inside the boundary layer that improve the exchange of motion. In this experimental and numerical study, we investigate the formation and evolution of vortices in the Reynolds number range of 106 and provide insights into flow patterns on surfaces with geometric changes. A detailed study of flow structure can be obtained from experimental and numerical evaluations. According to the results, there are significant vortex generators near the backpack due to high pressure. Immediately after the creation of these vortices, the flow is drawn and spread on the surface of the wing in three dimensions. As a result of the angle of attack, the wing surface separates prematurely. Based on the lift and drag coefficients, the study model showed the best performance in flight at an angle of attack of 10 degrees for this flow regime.
