A Thin Aerofoil of Small Camber in a Non-Uniform Flow

1967 ◽  
Vol 71 (675) ◽  
pp. 214-216
Author(s):  
L. N. Nigam
Keyword(s):  
Pressure Distribution ◽  
Stream Function ◽  
Constant Velocity ◽  
Direct Problem ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Angle Of Incidence ◽  
Pitching Moment ◽  
Image Position ◽  
General Profile

The direct problem of aerodynamics (profile of the aerofoil is given—calculate the aerodynamic characteristics) has been studied for thin aerofoils with small camber. Given the undisturbed stream functionV, ω, α being the constant velocity, vorticity and angle of incidence respectively, the pressure distribution, lift coefficient and pitching moment have been calculated for a general profile.

Investigation on Propeller Slipstream by Using an Unstructured Rans Solver Based on Overlapping Grids

2017 ◽  
Vol 34 (2) ◽  
pp. 89-101 ◽  
Author(s):  
X. Q. Gong ◽  
M. S. Ma ◽  
J. Zhang ◽  
J. Tang
Keyword(s):  
Pressure Distribution ◽  
Stokes Equations ◽  
Lift Coefficient ◽  
Linear Interpolation ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Overlapping Grids ◽  
Moment Coefficient ◽  
Grid Technique

AbstractBased on unstructured hybrid grid and dynamic overlapping grid technique, numerical simulations of Unsteady Reynolds Averaged Navier-Stokes equations were performed and investigation on isolated propeller aerodynamic characteristics and effects of propeller slipstream on turboprops were undertaken. The computational grid consisted of rotational subzone of propeller and stationary major-zone of aircraft, and walls criterion was used in the automatic hole-cutting procedure. Distance weight interpolation and tri-linear interpolation were developed to transfer information between the rotational and stationary subzones. The boundaries of overlapping grids were optimized for fixed axis rotation. The governing equations were solved by dual-time method and Lower Upper-Symmetric Gauss-Seidel method. The method and grid technique were verified by isolated propeller configuration and the computational results were in well agreement with the experimental data. The grid independence was studied to establish the numerical results. Finally, the flow around a turboprop case was simulated and the influence of propeller slipstream was presented by analyzing the surface pressure contours, profile pressure distribution, vorticity contours and profile streamline. It's indicated that the slipstream accelerates and rotates the free stream flow, changing the local angle of attack, enhancing the downwash effects, affecting the pressure distribution on wing and horizontal tail, as well as increasing the drag coefficient, pitching moment coefficient and the slope of lift coefficient.

scholarly journals Effect of Gurney Flap Geometry on a S809 Airfoil

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Li-Shu Hao ◽  
Yong-Wei Gao
Keyword(s):  
Numerical Simulation ◽  
Lift Force ◽  
Lift Coefficient ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Pitching Moment ◽  
Gurney Flaps ◽  
Gurney Flap ◽  
Linear And Nonlinear ◽  
Better Than

In this paper, the effect of Gurney flap shapes on wind turbine blade airfoil S809 has been studied by numerical simulation. First, the O-type grid is used in the numerical simulation. By comparing with experimental data, such as the lift force, the drag coefficient, and the pressure distribution, the accuracy of the simulation method is validated. Second, the research on the widths of three kinds of rectangular Gurney flaps at the trailing edge of the S809 airfoil is carried out. Rectangular Gurney flaps can considerably increase the lift in both the linear and nonlinear sections, and the maximum lift coefficient can be increased by 20.65%. In addition, the drag and the pitching moment are increased. However, the width of the rectangular Gurney flap has a small impact on the lift, the drag, and the pitching moment. Finally, the effects of rectangular and triangular Gurney flaps on the aerodynamic characteristics of the S809 airfoil are compared. The results show that the triangular flaps can obtain an increase of maximum lift coefficient by 28.42%, which is better than 16.31% of the rectangular flaps.

Research on Wind Turbine Airfoils Aerodynamic Performance of Trailing Edge Modification

2015 ◽  
Vol 741 ◽  
pp. 554-557
Author(s):  
Shang Ke Yuan ◽  
Zi Qin Zhao
Keyword(s):  
Pressure Distribution ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Trailing Edge ◽  
Airfoil Surface ◽  
Computation Result ◽  
Surface Pressure Distribution ◽  
Gurney Flap ◽  
Aerodynamic Performances ◽  
Turbine Airfoils

The airfoil commonly employed in wind turbines is modified by attaching a Gurney flap with length of 2% chord at its trailing edge and its remodeled form as well,but it showed special aerodynamic characteristics.The software FLUENT are respectively used to carry out numerical computation of aerodynamic performances of above-mentioned three airfoils, so that their aerodynamic characteristics, surface pressure distribution, and streamline around them are obtained for different angles of attack. It is shown by the computation result that the modified airfoils will result in such a strong downwash effect and the pressure distribution on airfoil surface is remarkably altered, the lift coefficient, and meantime the airfoil stalling is greatly postponed,but the airfoil of Gurney flap shown the characteristics of opposite.

scholarly journals The Influence of Ship Rolling Motion on Take-Off Aerodynamic Characteristics of Aircraft

2018 ◽  
Vol 25 (s2) ◽  
pp. 23-29
Author(s):  
He Zheng ◽  
Sun Xiao-yu ◽  
Gu Xuan
Keyword(s):  
Meshless Method ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Ship Motion ◽  
Maximum Speed ◽  
Rolling Motion ◽  
Pitching Moment ◽  
Rolling Moment ◽  
Side Force ◽  
Ship Rolling

Abstract Ship motion is an important factor affecting on the safety of ski-jump take-off. The simplified frigate ship SFS1 was numerically simulated, and the results were compared with the experimental data, the feasibility of the calculation method was verified; Meshless method and WALE turbulence model were used to simulate the process of aircraft ski-jump take-off, aerodynamic characteristics under different rolling conditions during the aircraft ski-jump take-off process were presented. The results showed that: the influence of ship rolling motion on lift coefficient, drag coefficient and pitching moment was small, side force and rolling moment were greatly affected by rolling motion; the region of downwash with the maximum speed was about 10 m from the bow; the safety of ski-jump take-off was greatly affected when aircraft was close to the bow within 20 m.

Numerical Study on Aerodynamic Characteristics of NACA0015

2013 ◽  
Vol 302 ◽  
pp. 640-645
Author(s):  
Su Jeong Lee ◽  
Eui Chul Jeong ◽  
Hee Chang Lim
Keyword(s):  
Pressure Distribution ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Aerodynamic Characteristics ◽  
Surface Pressure Distribution ◽  
Maximum Value ◽  
Stall Angle ◽  
Near Wall

In this study, a numerical simulation is made to understand the effect of the angle of attack on a NACA airfoil, which will be used for a basic shape to apply for making the vertical axis Darius wind turbine. The near-wall y+ value which is less than 1 is known to be most desirable for a near-wall modeling. Therefore, this study is aiming to observe the variation and find the optimized value of y+. The Reynolds number used in this study was 360,000, where the chord length and the velocity were 0.12m and 43.8m/s, respectively. Generally, the lift coefficient of the airfoil tends to increase as the angle of attack increases and it decreases substantially at the stall angle and then it decreases. As expected, the lift coefficient increases rapidly from 0 to 10° and then after the sudden drop of the lift (i.e., the stall) at around 10 to 16° depending on the y+ value. In this paper, it seems to be reliable and appropriate to use y+ value close to 1. From the surface pressure distribution, from the result obtained the ratio of pressure distribution of maximum value to the minimum value was 1.89and these peaks move forward to backward as the angle of attack increases.

The Effect of Nose Bluntness and Forebody Strakes on Aerodynamic Characteristics of Air-Launched Rocket Model

2013 ◽  
Vol 391 ◽  
pp. 143-149
Author(s):  
Yan Hua Zhang ◽  
Hua Xing Li ◽  
Deng Cheng Zhang ◽  
Liang Qu
Keyword(s):  
Wind Tunnel ◽  
Aerodynamic Characteristics ◽  
Angle Of Incidence ◽  
Pitching Moment ◽  
Longitudinal Stability ◽  
Side Force ◽  
Low Speed Wind Tunnel ◽  
Yaw Moment ◽  
Improve Stability ◽  
Blunt Nose

In this paper, the aerodynamic characteristics of the rocket model that might be used in a cabin air-launched system have been studied through experiments in low speed wind tunnel. The angle of incidence range is 0-80°, and the speed is 17m/s or 25m/s, including typical flight conditions prior to engine ignition. Forces and moments were measured through six-component balance. It is found that vortex asymmetry appears under certain condition with zero side slip. Asymmetrical phenomenon leads to larger side force and yaw moment, which can affect the trajectory of the rocket and put the carrier aircraft at risk. In addition, changes in regulation of the pitching moment with angle of attack are important to longitudinal stability, so the model with convergent-expanded afterbody was designed to improve stability. The effects of nose bluntness and forebody strakes on side force and yaw moment were presented, and the differences of aerodynamic characteristics with pointed and blunt nose, with and without forebody strakes were described. Results show that nose bluntness delays the appearance of asymmetric vortex, and the maximum side force is reduced by at least 50%. The forebody strakes reduce side force and yaw moment by weakening the asymmetric vortical interactions. The results can provide some references for designing the cabin air-launched rocket.

scholarly journals Numerical Simulation of the Aerodynamic Influence of Aircrafts During Aerial Refueling with Engine Jet

2019 ◽  
Vol 21 (1) ◽  
pp. 15-24 ◽  
Author(s):  
Yi Li ◽  
Yang Zhang ◽  
Junqiang Bai
Keyword(s):  
Stokes Equations ◽  
Dynamic Pressure ◽  
Lift Coefficient ◽  
Jet Flow ◽  
Aerodynamic Characteristics ◽  
Navier Stokes ◽  
Pitching Moment ◽  
Aerial Refueling ◽  
Rolling Moment ◽  
Moment Coefficient

Abstract Aerial refueling technology has been widely applied in various fields and it is one of the hotspots but difficulties for the aeronautical technologies. DLR-F6 WBNP model is used as a tanker and a fighter model is used as a receiver. The flow field of Probe–Drogue refueling and Flying Boom refueling is numerically simulated using the Reynolds-averaged Navier–Stokes equations, and the effects of the jet flow and the aerodynamic characteristics of the receiver are taken into consideration. The results indicate that the effect of downwash of the tanker reduces the lift coefficient and decreases the pitching moment coefficient of the receiver. The jet flow of tanker increases the dynamic pressure while decreases the local angle of attack, which increases the pressure difference between the upper and lower surfaces of receiver. Compared with the results without jet, the jet flow can increase the lift and the drag of the receiver and reduces the pitching moment, and even cause the change of rolling moment direction. Therefore, engine jet is an important factor when simulating aerial refueling.

Analysis Influence of Trailing Edge Modification on Aerodynamic Performance of Airfoils for Wind Turbine

2012 ◽  
Vol 220-223 ◽  
pp. 900-904 ◽  
Author(s):  
Shang Ke Yuan ◽  
Ren Nian Li
Keyword(s):  
Pressure Distribution ◽  
Characteristic Curve ◽  
Lift Coefficient ◽  
Simple Algorithm ◽  
Aerodynamic Characteristics ◽  
Trailing Edge ◽  
Airfoil Surface ◽  
Gurney Flap ◽  
Aerodynamic Performances ◽  
Volume Method

The airfoil NACA 4412 commonly employed in wind turbines is modified by attaching a Gurney flap with length of 2% chord at its trailing edge and its remodeled form as well. The SIMPLE algorithm of finite volume method and software FLUENT are respectively used to carry out numerical computation of aerodynamic performances of above-mentioned three airfoils (including the un-modified one), so that their aerodynamic characteristics, pressure distribution on their surface, and streamline around them are obtained for different angles of attack. It is shown by the computation result that the modified airfoils will result in such a strong downwash effect that the pressure distribution on airfoil surface is remarkably altered, the lift coefficient and as well as the slope of lift-drag characteristic curve are increased, and meantime the airfoil stalling is greatly postponed.

Design and simulation research of the double-spin folding mechanism based on a suspended missile

2021 ◽  
pp. 154851292110231
Author(s):  
ZH Yuan ◽  
SY Guo ◽  
SN Zhang ◽  
JQ Zhao ◽  
WJ Lu ◽  
...  
Keyword(s):  
High Reliability ◽  
Lift Coefficient ◽  
Great Influence ◽  
Reference Value ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Fluid Simulation ◽  
Simulation Research ◽  
Double Spin ◽  
Locking Mechanism

Based on the suspension of a missile using folding rotary wings and airbags, in order to improve the basic parameters and motion characteristics of the rotor during the unfolding process and analyze the aerodynamic characteristics of the entire device in the suspension state, after proposing a scheme of double-spin mechanism, the main folding and unfolding mechanism, initial driving device, rotating driving device, and locking mechanism were designed, and the simulation research is studied by the Automatic Dynamic Analysis of Mechanical System and Ansys Fluent Fluid Simulation software, respectively. The results show that the rotation rate was controlled at 41.8 mm/s, the various motion parameters are reasonable, and the operation process is relatively smooth, with high reliability. The speed and pressure value at the tip of the rotor are higher and the aerodynamic disturbance is obvious, which has a great influence on the aerodynamic performance. The speed and pressure distribution of the surrounding flow field is stable, the lift provided is 46 N, and the lift coefficient is 0.55, which can ensure the long-time suspension state of the missile. This paper puts forward a valuable design idea and has practical reference value for the research of the suspended missile.

Numerical study of the aerodynamic and power characteristics of the cycloidal rotor, under incoming flow

2019 ◽  
pp. 25-34
Author(s):  
Александр Анатольевич Дектерев ◽  
Артем Александрович Дектерев ◽  
Юрий Николаевич Горюнов
Keyword(s):  
Flow Velocity ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Simulation Method ◽  
Aerodynamic Characteristics ◽  
Incoming Flow ◽  
Ansys Fluent ◽  
Energy Characteristics ◽  
Power Characteristics ◽  
Calculation Results

Исследование направлено на разработку и апробацию методики численного моделирования аэродинамических и энергетических характеристик циклоидального ротора. За основу взята конфигурация ротора IAT21 L3. Для нее с использованием CFD-пакета ANSYS Fluent построена математическая модель и выполнен расчет. Проанализировано влияние скорости набегающего потока воздуха на движущийся ротор. Математическая модель и полученные результаты исследования могут быть использованы при создании летательных аппаратов с движителями роторного типа. This article addresses the study of the aerodynamic and energy characteristics of a cycloidal rotor subject to the influence of the incoming flow. Cycloidal rotor is one of the perspective devices that provide movement of aircrafts. Despite the fact that the concept of a cycloidal rotor arose in the early twentieth century, the model of a full-scale aircraft has not been yet realized. Foreign scientists have developed models of aircraft ranging in weight from 0.06 to 100 kg. The method of numerical calculation of the cycloidal rotor from the article [1] is considered and realized in this study. The purpose of study was the development and testing of a numerical simulation method for the cycloidal rotor and study aerodynamic and energy characteristics of the rotor in the hovering mode and under the influence of the oncoming flow. The aerodynamic and energy characteristics of the cycloidal rotor, rotating at a speed of 1000 rpm with incoming flow on it with velocities of 20-80 km/h, were calculated. The calculation results showed a directly proportional increase of thrust with an increase of the incoming on the rotor flow velocity, but the power consumed by the rotor was also increased. Increase of the incoming flow velocity leads to the proportional increasing of the lift coefficient and the coefficient of drag. Up to a speed of 80 km/h, an increase in thrust and power is observed; at higher speeds, there is a predominance of nonstationary effects and difficulties in estimating the aerodynamic characteristics of the rotor. In the future, it is planned to consider the 3D formulation of the problem combined with possibility of the flow coming from other sides.

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