Subsonic Wing-Body Interference for Missile Configurations at Large Angles of Attack

1977 ◽  
Vol 28 (3) ◽  
pp. 163-175 ◽  
Author(s):  
K D Thomson
Keyword(s):  
Normal Force ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
The Body ◽  
Supporting Evidence ◽  
Pitching Moment ◽  
Aerodynamic Properties ◽  
Moment Estimates ◽  
Effective Angle ◽  
Series Of Experiments

SummaryAn approximate method is presented for estimating the normal-force and pitching-moment characteristics (including the effects of wing-body interference) of wings mounted on bodies. A pair of wings placed side by side can be specified which, when operating at a certain angle of attack different from the geometrical angle of attack, have the same aerodynamic properties as the wings in the presence of the body. The equivalent wings and effective angle of attack are determined, and these enable the wing-body normal force and pitching moment to be estimated for wing-body combinations at angles of attack up to 90°. Comparisons made with the results of a specially conducted series of experiments on rectangular and delta planform wing-body combinations have provided gratifying supporting evidence for the theory.Estimates are also made of the normal force and pitching moment produced by two cone-cylinder bodies over the angle of attack range 0° to 90°. These estimates, when added to the wing-body normal-force and pitching-moment estimates, have resulted in a set of longitudinal aerodynamic characteristics which are generally close to those found experimentally. The method appears to have application in the preliminary design phase for slewing missiles.

The Influence of Non-linear Longitudinal Aerodynamic Characteristics on the Power Spectral Response of Aircraft to Atmospheric Turbulence

1973 ◽  
Vol 24 (4) ◽  
pp. 284-294
Author(s):  
P A T Christopher ◽  
J M H Dunn
Keyword(s):  
Root Mean Square ◽  
Normal Force ◽  
Spectral Response ◽  
Aerodynamic Characteristics ◽  
Pitching Moment ◽  
Mean Square ◽  
Acceleration Response ◽  
Spectral Technique ◽  
Power Spectral ◽  
Normal Acceleration

SummaryThe power spectral technique has been extended to show the effect of aerodynamic non-linearities on the normal acceleration response of a rigid aircraft in the cruise configuration. Non-linearities in the normal force and pitching moment variations with incidence have been considered. The resulting changes from the linear root-mean-square values of normal acceleration were only 3 to 5½% for a root-mean-square vertical gust velocity of 20 m/s.

scholarly journals Aerodynamic Study of the NASA’s X-43A Hypersonic Aircraft

2020 ◽  
Vol 10 (22) ◽  
pp. 8211
Author(s):  
Àlex Navó ◽  
Josep M. Bergada
Keyword(s):  
Angle Of Attack ◽  
Leading Edge ◽  
Aerodynamic Characteristics ◽  
Oblique Shock ◽  
Force Balance ◽  
Oblique Shock Wave ◽  
Vertical Force ◽  
Pitching Moment ◽  
Cfd Model ◽  
Hypersonic Aircraft

A 2D aerodynamic study of the NASA’s X-43A hypersonic aircraft is developed using two different approaches. The first one is analytical and based on the resolution of the oblique shock wave and Prandtl–Meyer expansion wave theories supported by an in-house program and considering a simplified aircraft’s design. The second approach involves the use of a Computational Fluid Dynamics (CFD) package, OpenFOAM and the real shape of the aircraft. The aerodynamic characteristics defined as the lift and drag coefficients, the aerodynamic efficiency and the pitching moment coefficient are calculated for different angles of attack. Evaluations are made for an incident Mach number of 7 and an altitude of 30 km. For both methodologies, the required angles of attack to achieve a Vertical Force Balance (VFB) and a completely zero pitching moment conditions are considered. In addition, an analysis to optimise the nose configuration of the aircraft is performed. The mass flow rate throughout the scramjet as a function of the angle of attack is also presented in the CFD model in addition to the pressure, density, temperature and Mach fields. Before presenting the corresponding results, a comparison between the aerodynamic coefficients in terms of the angle of attack of both models is carried out in order to properly validate the CFD model. The paper clarifies the requirements needed to make sure that both oblique shock waves originating from the leading edge meet just at the scramjet inlet clarifying the advantages of fulfilling such condition.

scholarly journals Numerical Calculation of Effect of Elastic Deformation on Aerodynamic Characteristics of a Rocket

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Laith K. Abbas ◽  
Dongyang Chen ◽  
Xiaoting Rui
Keyword(s):  
Lift Force ◽  
Normal Force ◽  
Center Of Pressure ◽  
Aerodynamic Characteristics ◽  
Force Distribution ◽  
Pitching Moment ◽  
Flight Trajectory ◽  
Aerodynamic Coefficients ◽  
Computational Fluid Dynamics Cfd ◽  
Drag And Lift

The application and workflow of Computational Fluid Dynamics (CFD)/Computational Structure Dynamics (CSD) on solving the static aeroelastic problem of a slender rocket are introduced. To predict static aeroelastic behavior accurately, two-way coupling and inertia relief methods are used to calculate the static deformations and aerodynamic characteristics of the deformed rocket. The aerodynamic coefficients of rigid rocket are computed firstly and compared with the experimental data, which verified the accuracy of CFD output. The results of the analysis for elastic rocket in the nonspinning and spinning states are compared with the rigid ones. The results highlight that the rocket deformation aspects are decided by the normal force distribution along the rocket length. Rocket deformation becomes larger with increasing the flight angle of attack. Drag and lift force coefficients decrease and pitching moment coefficients increase due to rocket deformations, center of pressure location forwards, and stability of the rockets decreases. Accordingly, the flight trajectory may be affected by the change of these aerodynamic coefficients and stability.

scholarly journals Comparison of Aerodynamic Properties of Badminton Feather and Synthetic Shuttlecocks

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 104
Author(s):  
Kenichi Nakagawa ◽  
Hiroaki Hasegawa ◽  
Masahide Murakami
Keyword(s):  
Wind Tunnel ◽  
High Stability ◽  
Angle Of Attack ◽  
Pitching Moment ◽  
Wind Tunnel Experiments ◽  
Aerodynamic Stability ◽  
Fluid Forces ◽  
Moment Coefficient ◽  
Aerodynamic Properties ◽  
The Difference

The purpose of this study is to investigate the difference in aerodynamic properties between the feather shuttlecock and the synthetic shuttlecock. In particular, we focus on the aerodynamic stability of the two types of shuttlecock during impulsive change of an angle of attack (flip movement). Wind tunnel experiments are performed by using two types of the badminton shuttlecock (feather and synthetic shuttlecocks) to measure the fluid forces, and to visualize the flow fields around the shuttlecock. It is confirmed that the pitching moment coefficient at a near-zero angle-of-attack for feather shuttlecock is larger than that for synthetic shuttlecock. The results indicate that the feather shuttlecock demonstrates high stability in response to the flip phenomenon.

scholarly journals Features of subsonic air flow around perforated plates

2020 ◽  
Author(s):  
A.G. Golubev ◽  
E.G. Stolyarova ◽  
M.D. Kalugina
Keyword(s):  
Normal Force ◽  
Air Flow ◽  
Angle Of Attack ◽  
Vertical Plane ◽  
Perforated Plate ◽  
Aerodynamic Characteristics ◽  
Perforated Plates ◽  
Subsonic Speed ◽  
Solid Plate ◽  
Zero Degree

The paper considers the process of flow around a flat plate with rounded front and side edges at various degrees of surface perforation. The flow patterns were studied both near the plate with zero degree of perforation, and at the surface of plates with a perforation degree of more than 20%. The features of air flow directly inside the holes at various values of the angle of attack are considered. Isobars of pressure distribution in the vertical plane of the flow over a solid plate are given. A simulation of the flow around a perforated plate at subsonic speed of the incoming air flow is performed, aerodynamic characteristics are obtained and graphical dependencies of the aerodynamic coefficients of longitudinal and normal force on the angle of attack are presented. Special attention is paid to the comparative analysis of aerodynamic characteristics for solid (with zero degree of perforation) and perforated plates.

Aerodynamic Characteristics of an Airfoil with Boundary Layer Ingestion in Subsonic Flow

2014 ◽  
Vol 670-671 ◽  
pp. 609-612 ◽  
Author(s):  
Jiang Hao Wu ◽  
Xue Mei Li
Keyword(s):  
Boundary Layer ◽  
Numerical Method ◽  
Mass Flow ◽  
Small Angle ◽  
Subsonic Flow ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Pitching Moment ◽  
Flow Ratio ◽  
Mass Flow Ratio

The influence of boundary layer ingestion (BLI) on the aerodynamics of airfoil RAE2822 in subsonic is investigated by numerical method. Based on the calculation, it is found that the mass flow ratio (MFR), intake height, cowl length and intake position in the chord can affect on the lift, drag and pitching moment remarkable. Considering a maximum lift-over-drag, intake position in the chord should be rearward as possible with a certain high MFR at a small angle of attack and a considerable intake height. There is a proper MFR which makes drag lowest.

scholarly journals Gull-inspired joint-driven wing morphing allows adaptive longitudinal flight control

2021 ◽  
Vol 18 (179) ◽  
pp. 20210132
Author(s):  
C. Harvey ◽  
V. B. Baliga ◽  
C. D. Goates ◽  
D. F. Hunsaker ◽  
D. J. Inman
Keyword(s):  
Flight Control ◽  
Control Strategies ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Pitching Moment ◽  
Motion Trajectories ◽  
Aerodynamic Properties ◽  
Aerial Vehicle ◽  
Wing Morphing ◽  
Lifting Line

Birds dynamically adapt to disparate flight behaviours and unpredictable environments by actively manipulating their skeletal joints to change their wing shape. This in-flight adaptability has inspired many unmanned aerial vehicle (UAV) wings, which predominately morph within a single geometric plane. By contrast, avian joint-driven wing morphing produces a diverse set of non-planar wing shapes. Here, we investigated if joint-driven wing morphing is desirable for UAVs by quantifying the longitudinal aerodynamic characteristics of gull-inspired wing-body configurations. We used a numerical lifting-line algorithm (MachUpX) to determine the aerodynamic loads across the range of motion of the elbow and wrist, which was validated with wind tunnel tests using three-dimensional printed wing-body models. We found that joint-driven wing morphing effectively controls lift, pitching moment and static margin, but other mechanisms are required to trim. Within the range of wing extension capability, specific paths of joint motion (trajectories) permit distinct longitudinal flight control strategies. We identified two unique trajectories that decoupled stability from lift and pitching moment generation. Further, extension along the trajectory inherent to the musculoskeletal linkage system produced the largest changes to the investigated aerodynamic properties. Collectively, our results show that gull-inspired joint-driven wing morphing allows adaptive longitudinal flight control and could promote multifunctional UAV designs.

Aerodynamic characteristics of a dual-spin projectile with canards

2019 ◽  
Vol 233 (12) ◽  
pp. 4541-4553
Author(s):  
Xiaodong Liu ◽  
Xiaosheng Wu ◽  
Jintao Yin
Keyword(s):  
Mach Number ◽  
Normal Force ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Lateral Force ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Force Coefficient ◽  
Sliding Mesh ◽  
Flow Mechanisms

Based on the three-dimensional Navier–Stokes (N–S) equations, using unsteady numerical technology, flow over a dual-spin projectile was simulated to investigate its aerodynamic characteristics during flight. Spin was achieved via the sliding mesh method. The influence laws of the aftbody spin rate, Mach number, and angle of attack on the aerodynamic characteristics of the projectile are presented, and the flow mechanisms for the laws are revealed. The results demonstrate that the influence of the aftbody spin rate on the normal force coefficient is very small, whereas, on the lateral force coefficient, it is larger. With the increase in the Mach number, the time-averaged normal force coefficient and lateral force coefficient increase, while the fluctuation quantities of the normal force coefficient and the lateral force coefficient decrease. The variation of angle of attack will influence the size, distribution, and interference effect of the shedding vortices.

Aerodynamic Investigations of Low-Aspect-Ratio Thin Plate Wings at Low Reynolds Numbers

2012 ◽  
Vol 28 (1) ◽  
pp. 77-89 ◽  
Author(s):  
Y.-C. Liu ◽  
F.-B. Hsiao
Keyword(s):  
Aspect Ratio ◽  
Thin Plate ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Flow Structures ◽  
Low Aspect Ratio ◽  
Aerodynamic Properties ◽  
Stall Angle

ABSTRACTTo realize the relationship between flow structures of wingtip vortices and post stall characteristics of low aspect-ratio wings, this paper experimentally studies the aerodynamic characteristics and the corresponding flow structures of the rectangular thin-plate wings at Reynolds numbers between 104 and 105. The aerodynamic properties to be studied include lift, drag, slopes at linear and nonlinear range of the lift curves and lift-to-drag ratios of the tested wings with the aspect ratio varying from 1.0 to 3.0. The flow structures regarding the leading-edge separation vortices and wingtip vortices at upper surface and near-wake regions of the wings are also investigated by smoke-wire visualization. Results indicate that the high stall angle of attack and vortex lift are clearly manifested to induce the nonlinear increase in the lift curves as the aspect ratio reaches less than 1.6. This phenomenon is specifically observed to augment the aerodynamic properties with the decrease of the aspect ratio. Additionally, the corresponding flow visualization also indicates that the wingtip vortices and the areas of highly affected regions are duly increased with the increase of the angle of attack up to 40°, which makes certain that the extra increase of the nonlinear lift results from these vortices. This result can be practically applied to the planform design for unmanned aerial vehicles.

scholarly journals Extensions of d'Alembert's paradox for elongated bodies

2015 ◽  
Vol 471 (2181) ◽  
pp. 20150106
Author(s):  
Philippe R. Spalart
Keyword(s):  
Cross Section ◽  
Unit Length ◽  
Angle Of Attack ◽  
Three Dimensional ◽  
Added Mass ◽  
The Body ◽  
Pitching Moment ◽  
Constant Cross Section ◽  
Slender Body Theory ◽  
The Cross

The steady incompressible irrotational flow past a three-dimensional body of any shape generates no forces. The historic paradox refers only to drag, but lift is also zero, which has been known but not emphasized. The new material concerns a body with a long constant cross section, such as a train. The final results for forces and moments are very simple. With zero angle of attack, we show that the force vectors on the front and rear parts of the body are each (asymptotically) equal to zero, if the pressure is referred to the freestream pressure. The lift and drag coefficients, based on frontal area, vanish proportionally to d / l and ( d / l ) 2 , respectively, where d / l is the diameter-to-length ratio. This applies to any shape of the cross section, and of the ends. With an angle of attack, the nose and tail forces are non-zero but depend only on the angle of attack and the cross section's added mass per unit length. The pitching moment is proportional to the total added mass and the sine of twice the angle of attack. The present results clarify slender-body theory results. The practical consequence is that, for a long body with constant cross section, the shape of the nose or the tail is irrelevant to its own ‘partial’ drag and lift, and to the pitching moment.

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