AERODYNAMIC CHARACTERISTICS OF VARIOUS TYPES OF FULL SCALE PARACHUTES AT MACH NUMBERS FROM 1.8 TO 3.0

Author(s):  
J. F. Lowry
1940 ◽  
Vol 44 (352) ◽  
pp. 338-349
Author(s):  
A. P. West

During the past few years an extensive amount of experimental data on split flaps has been made available to the aircraft industry, through the publications of aeronautical research laboratories, both in this country and abroad. In general, each publication deals with one particular aspect of the problem, and when the effect of wing flaps on the performance of an aircraft is being estimated a certain amount of difficulty may be experienced in deciding which of the many reports available gives results most readily applicable to the case being considered ; and what allowances, if any, should be made for wing taper, flap cut-out, fuselage, etc.In this report the available data has been analysed with a view to answering these questions, and presented in such a form that it may be readily applied to determine the most probable change in the aerodynamic characteristics of a wing that may be expected from the use of this type of flap.From the appendix an estimate of the accuracy of the method can be obtained, as a comparison with full-scale data is given for lift and drag, and for the other flap characteristics the original curves have been reproduced.


2021 ◽  
Vol 1201 (1) ◽  
pp. 012007
Author(s):  
I. Kusano ◽  
E. Cheynet ◽  
J. B. Jakobsen ◽  
J. Snæbjörnsson

Abstract Assessing the aerodynamic characteristics of long-span bridges is fundamental for their design. Depending on the terrain complexity and local wind conditions, episodes of large angles of attack (AoA) of 15° may be observed. However, such large AoAs ( above 10°) are often overlooked in the design process. This paper studies the aerodynamics properties of a flow around a single-box girder for a wide range of AoAs, from –20° to 20°, using numerical simulations. The simulations are based on a 2D unsteady Reynolds-averaged Navier–Stokes (URANS) approach using the k − ω SST turbulence model with a Reynolds number of 1.6 × 105. Numerically obtained aerodynamic static coefficients were compared to wind tunnel test data. The CFD results were generally in good agreement with the wind tunnel tests, especially for small AoAs and positive AoAs. More discrepancies were observed for large negative AoA, likely due to the limitation of modelling 3D railings with 2D simulations. The simulated velocity deficit downstream of the deck was consistent with the one measured in full-scale using short-range Doppler wind lidar instruments. Finally, the Strouhal number from the CFD simulations were in agreement with the value obtained from the full-scale data.


2013 ◽  
Vol 444-445 ◽  
pp. 221-226
Author(s):  
Xin Xu ◽  
Da Wei Liu ◽  
De Hua Chen ◽  
Yuan Jing Wang

The shock-induced separation easily occurred on the upper surface of supercritical airfoil at transonic speeds, which would change the aerodynamic characteristics. The problem of the shock-induced separation was not solved completely for the complicated phenomena and flow mechanism. In this paper, the influencing factors of shock-induced separation for supercritical airfoil CH was analyzed at transonic speeds. The Navier-Stokes equations were solved, in order to investigate influence of different attack angles, Mach numbers and Reynolds numbers. The computation attack angles of CH airfoil varied from 0oto 7o, Reynolds numbers varied from 5×106to 50×106per airfoil chord while Mach number varied from 0.74 to 0.82. It was shown that the shock-induced separation was affected by attack angles, Mach numbers and Reynolds numbers, but the influence tendency and areas were quite different. The shock wave location and intensity were affected by the three factors, and the boundary layer thickness was mainly affected by Reynolds number, while the separation structure was mainly determined by the attack angle and Mach number.


Author(s):  
D Maruyama ◽  
K Kusunose ◽  
K Matsushima ◽  
K Nakahashi

Aiming to realize a low-drag supersonic transport, Busemann biplane concept was adopted in this study. Two- and three-dimensional (2D and 3D) biplanes were analysed and designed to improve their aerodynamic performance using computational fluid dynamics. It was confirmed that 3D biplane wings have better aerodynamic-performance areas than 2D biplane airfoils. A winglet is also useful for improvement of their aerodynamic performance. Aerodynamic characteristics of these biplanes at their off-design conditions were also analysed. In 3D wings, a flow choking and its attendant hysteresis as starting problems, which arise when the biplanes accelerate from low Mach numbers, disappear at lower Mach numbers than those in 2D airfoils. It was confirmed that hinged slats and flaps are effective to settle these issues. Finally, interference effects of a body with the biplanes were investigated. When the biplane wings are affected by the expansion waves from the body, their aerodynamic performance at the design Mach number and the starting Mach number are better and lower than those of their isolated wings, respectively. A 3D biplane wing obtained by an inverse-design method was applied to the body. The wing of this wing–body configuration achieves higher aerodynamic performance than the 2D flat-plate airfoil at sufficient lift conditions, which is the almost identical performance of 2D biplane airfoils.


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