scholarly journals Research on Aerodynamic Shape Design Scheme of a Distributed Propeller Transport Aircraft and Its Slipstream Effect

2019 ◽  
Vol 37 (2) ◽  
pp. 361-368
Author(s):  
Xiaochuan Yang ◽  
Wei Li ◽  
Yuntao Wang ◽  
Hao Wang ◽  
Hao Yue ◽  
...  
Keyword(s):  
Electric Propulsion ◽  
Aerodynamic Characteristics ◽  
Small Scale ◽  
Pitching Moment ◽  
Disk Model ◽  
Transport Aircraft ◽  
Design Scheme ◽  
The Difference ◽  
Lift And Drag ◽  
High Thrust

With the continuous development and widespread attention of electric propulsion technology in traditional transportation fields such as automobiles and trains, the distributed propeller propulsion technology applied to electric or hybrid electric medium and small scale aircrafts has become a new topic in aviation research. This paper presents a preliminary design scheme of a distributed propeller electric propulsion transport aircraft firstly. Then, based on Reynolds average N-S equations, combined with the SA turbulence model, and replaced the real distributed propellers with simplified disk model, the aerodynamic characteristics of the aircraft with and without slipstream under the condition of low speed and high thrust at low altitude are analyzed. Finally, the effects of pressure distribution, pitching moment characteristics and wing flow on distributed propellers are studied in detailed. The results show that the lift and drag of the aircraft with slipstream are both larger than without slipstream and with slipstream effect, the pitching moment of the wing decreases, the pitching moment of the tail increases. When the tail is far away or completely inside the region of slipstream, the difference of pitching moment of the tail with and without slipstream is little, and the difference is obvious as the tail is only partially in the region of slipstream; When the diameter of distributed propellers is far larger than the wing thickness, more propeller power is used to shove air flow away from the surface area of the wing, and resulting in an insignificant increase in the coefficient of lift.

scholarly journals Aerodynamic Analysis of a Flapping Wing Aircraft for Short Landing

2020 ◽  
Vol 10 (10) ◽  
pp. 3404
Author(s):  
Bing Ji ◽  
Zenggang Zhu ◽  
Shijun Guo ◽  
Si Chen ◽  
Qiaolin Zhu ◽  
...  
Keyword(s):  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Aerodynamic Analysis ◽  
Drag Forces ◽  
Wing Model ◽  
Aerodynamic Model ◽  
Computational Fluid Dynamics Cfd ◽  
The Difference ◽  
Cfd Method ◽  
Lift And Drag

An investigation into the aerodynamic characteristics has been presented for a bio-inspired flapping wing aircraft. Firstly, a mechanism has been developed to transform the usual rotation powered by a motor to a combined flapping and pitching motion of the flapping wing. Secondly, an experimental model of the flapping wing aircraft has been built and tested to measure the motion and aerodynamic forces produced by the flapping wing. Thirdly, aerodynamic analysis is carried out based on the measured motion of the flapping wing model using an unsteady aerodynamic model (UAM) and validated by a computational fluid dynamics (CFD) method. The difference of the average lift force between the UAM and CFD method is 1.3%, and the difference between the UAM and experimental results is 18%. In addition, a parametric study is carried out by employing the UAM method to analyze the effect of variations of the pitching angle on the aerodynamic lift and drag forces. According to the study, the pitching amplitude for maximum lift is in the range of 60°~70° as the flight velocity decreases from 5 m/s to 1 m/s during landing.

A Modular Wing-Tail Airplane Configuration for the Educational Wind Tunnel Laboratory

2004 ◽  
Author(s):  
B. Terry Beck
Keyword(s):  
Wind Tunnel ◽  
Rapid Prototyping ◽  
Calibration Procedure ◽  
Aerodynamic Characteristics ◽  
Wind Tunnels ◽  
Small Scale ◽  
Pitching Moment ◽  
Gravity Effects ◽  
Basic Parameters ◽  
Rapid Prototyping System

An innovative modular airplane configuration has been developed for use in small-scale educational wind tunnels. The “airplane” consists of an interchangeable wing and horizontal tail configuration that mounts on a conventional wind tunnel electronic balance (“sting”) to facilitate measurements of normal force, axial force and longitudinal pitching moment. From these basic parameters, the total lift, total drag, and resultant airplane pitching moment can be deduced, along with the location of the aerodynamic center of the total airplane. Using known wing planform and airfoil shapes facilitates comparison of the total airplane aerodynamic characteristics with those predicted from the known characteristics of the separate wing and horizontal tail. In particular, the aerodynamic center of the simplified airplane configuration can be determined, along with the effect that downwash on the tail has on longitudinal stability of the airplane. Included in the paper is a description of the calibration procedure for the modular “sting” mount. This procedure accounts for an offset “line of action” for aerodynamic forces, as well as offset center of gravity effects. In conjunction with this same test setup, an available Rapid Prototyping system has been used to manufacture the test sections (separate wing and tail) for use in the wind tunnel, and in particular, in the modular wing-tail assembly. This provides tremendous flexibility in the types of wing-tail assemblies that can be investigated experimentally using the same module. The relatively inexpensive prototyping procedure also provides the capability for students to design and test their own configurations. Furthermore, the precision manufacturing capability of the Rapid Prototyping system guarantees reliable reproduction of virtually any desired aerodynamic planform and airfoil shape.

scholarly journals Choosing the aerodynamic configuration of a subsonic cruise missile

2019 ◽  
Vol 18 (3) ◽  
pp. 59-66
Author(s):  
M. A. Kovalev ◽  
A. N. Nikitin
Keyword(s):  
Aerodynamic Characteristics ◽  
Cruise Missile ◽  
Swept Wing ◽  
Horizontal Flight ◽  
Wide Range ◽  
The Difference ◽  
Cruise Missiles ◽  
Lift And Drag ◽  
Aerodynamic Configuration ◽  
Aerodynamic Quality

The paper presents a comparison of two aerodynamic configurations of subsonic cruise missiles, characterized by the use of swept-back and forward-swept wings. The results of wind tunnel tests with the use of an automated measurement system characterizing the dependence of the lift and drag coefficients in a sufficiently wide range of angles of attack are presented. This allows us to compare the aerodynamic quality of the cruise missile models under investigation. The analysis of the results of experiments with the models and calculations in conditions of steady-state low-altitude horizontal flight revealed that the configurations of cruise missiles with a moderately swept wing, selected for comparison, have similar aerodynamic characteristics. Both configurations ensure the mode of flight at a given altitude and velocity in the range of the best angles of attack (maximum aerodynamic quality). Missiles with swept-back wings have better aerodynamic performance in terms of maximum aerodynamic quality, while the lift increment due to reduced trim losses for the forward-swept wing configuration only partially compensates the difference of the aerodynamic characteristics of the alternatives under consideration. Therefore, it is concluded that the choice of aerodynamic configuration of a subsonic cruise missile with a swept-back wing is preferable.

scholarly journals Effects of Pitching Motion Elements on Aerodynamic Characteristics of Airfoil

2021 ◽  
Vol 2076 (1) ◽  
pp. 012078
Author(s):  
Rui Yin ◽  
Jing Huang ◽  
Zhi-Yuan He
Keyword(s):  
Drag Coefficient ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Characteristics ◽  
Initial Angle ◽  
Pitching Motion ◽  
The Difference ◽  
Lift And Drag ◽  
Drag Ratio ◽  
Lift To Drag Ratio

Abstract The aerodynamic characteristics of NACA4412 airfoil with different pitching motion elements were compared and analyzed based on CFD in this research. The results are acquired as follows: the difference between the lift and drag coefficients of the airfoil during pitch up and pitch down motions becomes larger with the increase of the pitching amplitude or initial angle of attack; as the pitching amplitude increases, the lift coefficient grows slightly greater and the drag coefficient grows much greater; as the initial angle of attack increases, the lift coefficient grows much greater and the drag coefficient grows slightly; the smaller the attenuation frequency is, the larger the lift-to-drag ratio of the airfoil will be.

scholarly journals Investigation of a Light Boxplane Model Using Tuft Flow Visualization and CFD

Fluids ◽  
2021 ◽  
Vol 6 (12) ◽  
pp. 451
Author(s):  
Karpovich Elena ◽  
Gueraiche Djahid ◽  
Sergeeva Natalya ◽  
Kuznetsov Alexander
Keyword(s):  
Aerodynamic Characteristics ◽  
Scale Model ◽  
Lateral Stability ◽  
Pitching Moment ◽  
High Lift ◽  
Moment Coefficient ◽  
Stability Derivatives ◽  
Predictive Methods ◽  
The Difference ◽  
Local Reynolds Number

In this paper, we addressed the flow patterns over a light boxplane scale model to explain the previously discovered disagreement between its predicted and experimental aerodynamic characteristics. By tuft flow and CFD visualization, we explored the causes yielding a large zero lift pitching moment coefficient, lateral divergence, difference in fore and aft elevator lift, and poor high lift performance of the aircraft. The investigation revealed that the discrepancy in the pitching moment coefficient and lateral stability derivatives can be attributed to insufficient accuracy of the used predictive methods. The difference in fore and aft elevator lift and poor high lift performance of the aircraft may occur due to the low local Reynolds number, which causes the early flow separation over the elevators and flaperons when deflected downward at angles exceeding 10°. Additionally, some airframe changes are suggested to alleviate the lateral divergence of the model.

scholarly journals Computational Study Of Curved Underbody Diffusers

2019 ◽  
Vol 128 ◽  
pp. 10002
Author(s):  
Angel Huminic ◽  
Gabriela Huminic
Keyword(s):  
Computational Study ◽  
Aerodynamic Characteristics ◽  
Passenger Car ◽  
Lift And Drag ◽  
Underbody Diffuser ◽  
Ahmed Body

This paper presents new results concerning the aerodynamics of the Ahmed body fitted with a non-flat underbody diffuser. As in previous investigations performed, the angle and the length of the diffuser are the parameters systematically varied within ranges relevant for a hatchback passenger car. Coefficients of lift and drag are compared with the values obtained for the flat underbody diffuser, and the results reveal significant improvements concerning aerodynamic characteristics of body.

Numerical study of geometric morphing wings of the 1303 UCAV

2021 ◽  
pp. 1-17
Author(s):  
B. Nugroho ◽  
J. Brett ◽  
B.T. Bleckly ◽  
R.C. Chin
Keyword(s):  
Flight Control ◽  
Numerical Study ◽  
Aerodynamic Characteristics ◽  
Morphing Wing ◽  
Rolling Moment ◽  
Wide Range ◽  
Morphing Wings ◽  
Wing Geometry ◽  
Lift And Drag ◽  
Wing Morphing

ABSTRACT Unmanned Combat Aerial Vehicles (UCAVs) are believed by many to be the future of aerial strike/reconnaissance capability. This belief led to the design of the UCAV 1303 by Boeing Phantom Works and the US Airforce Lab in the late 1990s. Because UCAV 1303 is expected to take on a wide range of mission roles that are risky for human pilots, it needs to be highly adaptable. Geometric morphing can provide such adaptability and allow the UCAV 1303 to optimise its physical feature mid-flight to increase the lift-to-drag ratio, manoeuvrability, cruise distance, flight control, etc. This capability is extremely beneficial since it will enable the UCAV to reconcile conflicting mission requirements (e.g. loiter and dash within the same mission). In this study, we conduct several modifications to the wing geometry of UCAV 1303 via Computational Fluid Dynamics (CFD) to analyse its aerodynamic characteristics produced by a range of different wing geometric morphs. Here we look into two specific geometric morphing wings: linear twists on one of the wings and linear twists at both wings (wash-in and washout). A baseline CFD of the UCAV 1303 without any wing morphing is validated against published wind tunnel data, before proceeding to simulate morphing wing configurations. The results show that geometric morphing wing influences the UCAV-1303 aerodynamic characteristics significantly, improving the coefficient of lift and drag, pitching moment and rolling moment.

scholarly journals Visual Simulation of Detailed Turbulent Water by Preserving the Thin Sheets of Fluid

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 502 ◽  
Author(s):  
Jong-Hyun Kim ◽  
Wook Kim ◽  
Young Kim ◽  
Jung Lee
Keyword(s):  
Turbulent Flows ◽  
Visual Simulation ◽  
Numerical Dissipation ◽  
Small Scale ◽  
Thin Sheets ◽  
Global Flow ◽  
Low Mass ◽  
The Difference ◽  
Water Simulation ◽  
Turbulent Water

When we perform particle-based water simulation, water particles are often increased dramatically because of particle splitting around breaking holes to maintain the thin fluid sheets. Because most of the existing approaches do not consider the volume of the water particles, the water particles must have a very low mass to satisfy the law of the conservation of mass. This phenomenon smears the motion of the water, which would otherwise result in splashing, thereby resulting in artifacts such as numerical dissipation. Thus, we propose a new fluid-implicit, particle-based framework for maintaining and representing the thin sheets and turbulent flows of water. After splitting the water particles, the proposed method uses the ghost density and ghost mass to redistribute the difference in mass based on the volume of the water particles. Next, small-scale turbulent flows are formed in local regions and transferred in a smooth manner to the global flow field. Our results show us the turbulence details as well as the thin sheets of water, thereby obtaining an aesthetically pleasing improvement compared with existing methods.

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