scholarly journals Analytic determination of tandem-scheme aircraft aerodynamic characteristics

2015 ◽  
pp. 59-71
Author(s):  
Ілля Станіславович Кривохатько ◽  
Віталій Вікторович Сухов
Keyword(s):  
Mathematical Model ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Design ◽  
New Approach ◽  
Definite Integrals ◽  
Moment Coefficient ◽  
Numerical Computing ◽  
Theoretical Results

In present article analytic method of downwash after wing, lift coefficient and pitching moment coefficient determination for tandem-scheme aircraft was upgraded. Mathematical model is based on Bio-Savart formula and avoid approximate calculus of indefinite integrals in contrast to classical theory. Instead of it new approach consists on numerical computing of definite integrals with high accuracy (error less than 10­-5 was achieved). Method is appropriate for low Mach number and for any Reynolds number. Theoretical results calculated according to proposed method were compared with wind tunnel experiment data and showed good agreement.Developed mathematical model allows optimization of tandem-scheme aircraft aerodynamic design with different objective function. In the next works method will be expanded on the lateral aerodynamic characteristics.

scholarly journals Experimental Investigation of the Ground Effect of WIG Craft—NEW1 Model

Proceedings ◽  
2020 ◽  
Vol 39 (1) ◽  
pp. 17
Author(s):  
Sakornsin ◽  
Thipyopas ◽  
Atipan
Keyword(s):  
Lift Coefficient ◽  
Ground Surface ◽  
Ground Effect ◽  
Aerodynamic Characteristics ◽  
Scale Model ◽  
Negative Slope ◽  
Stream Velocity ◽  
Longitudinal Stability ◽  
Moment Coefficient ◽  
The Moment

Navy Experimental Wing-in-Ground-Effect (WIG) craft namely as NEW1, is the first version of 2-seated WIG craft which has been designed and developed by Royal Thai Navy since 2017. This experimental research is a part of the NEW1 project which aims to investigate the aerodynamic characteristics and aspects of the flow passing through the WIG craft model when in ground effect. In the experiment, the WIG craft—NEW1 of 1:15 scale model is tested in a close circuit wind tunnel of 1 m × 1 m test section at Kasetsart University. The tests are conducted at the free stream velocity of 40 m/s or Reynolds number of 280,000, at angles of attack ranging from −9° to 21°, and at the wing to ground distances ranging from 5.0 C to 0.3 C. The measurement of 6-DoF of forces and moments and pressure distributions on the ground surface underneath the WIG craft model are made during the tests. The results show that the ground has significant effects on the aerodynamic characteristics of the WIG craft model when the wing to ground distance is less than its mean chord. It was found that when the model move from 5.0 C (out of ground effect) to 0.3 C, the lift coefficient increases up to 15.7%, the drag coefficient decreases up to 5.6%, and the lift to drag ratio increases 33.4%. The proximity of the model to the ground also affects the longitudinal stability of the model. The moment coefficient curves against angle of attack has negative slope for both in and out of ground effect indicating favorable longitudinal stability. However, it was found that the aerodynamic center move further aft toward the trailing edge when the model move closer to the ground.

The Effect of Canard to the Aerodynamic Behavior of Blended Wing Body Aircraft

2012 ◽  
Vol 225 ◽  
pp. 38-42
Author(s):  
Zurriati Mohd Ali ◽  
Wahyu Kuntjoro ◽  
Wisnoe Wirachman
Keyword(s):  
Mach Number ◽  
Wind Tunnel ◽  
Aerodynamic Characteristic ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Moment Coefficient ◽  
Subsonic Wind Tunnel ◽  
Setting Angle ◽  
Blended Wing Body ◽  
The Moment

This paper presents a study on the effect of canard setting angle on the aerodynamic characteristic of a Blended Wing Body (BWB). Canard effects to BWB aerodynamic characteristics are not widely investigated. Hence the focus of the study is to investigate the variations of lifts, drags and moments when the angles of attack are varied at different canard setting angles. Wind tunnel tests were performed on BWB aircraft with canard setting angles,  ranging from -20˚ to 20˚. Angles of attack,  were varied from -10˚ to 10˚. Aspect ratio and canard planform area were kept fixed. All tests were conducted in the subsonic wind tunnel at Universiti Teknologi MARA, at Mach number of 0.1. The streamlines flow, at the upper surface of the canard was visualized using mini tuft. Result shows that the lift coefficient does not change much with different canard setting angles. As expected, the lift coefficient increases with increasing angles of attack at any canard setting angle. In general, the moment coefficient increases as the canard setting angle is increased. The results obtained in this research will be of importance to the understanding of aerodynamic behavior of BWB employing canard in its configuration.

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.

Numerical and Experimental Study of the Influence of Damage on the Aerodynamic Characteristics of a Finite Wing

2011 ◽  
Author(s):  
Soheila Abdolahipour ◽  
Mahmoud Mani ◽  
Ghazaleh M. Ahmadi Dehaghi
Keyword(s):  
Stream Flow ◽  
Reverse Flow ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Aerodynamic Coefficients ◽  
Moment Coefficient ◽  
Through Flow ◽  
Root Position ◽  
Flow Through ◽  
Finite Wing

In this paper the flow on a finite wing with star shape damage is numerically and experimentally investigated to understand the influences of damage on the aerodynamic characteristics of wing. To study the effects of different span positions, the damage was considered in tip, middle and root position of the wing span. The aerodynamic coefficients and their increments due to damage were extracted and the results were compared to each other and also to the results of experimental. Then flow visualizations were practiced to make evident the flow structure on the model and to help to understand the influences of each position of damage on the aerodynamic coefficients. There was the flow through the damage which was driven by the pressure difference between the upper and lower wing surfaces. The flow could take two forms dependent on the angle of attack. The first form was a “weak-jet” which formed an attached wake and resulted in small changes in force and moment coefficients. The second form resulted from increased incidence. This was the “strong-jet” where through flow penetrated into the free stream flow with large separated wake and reverse flow. The effect on the force and moment coefficients was significant in this case. Generally comparing to an undamaged model, increasing incidence for a damaged model resulted increase loss of lift coefficient, increased drag coefficient and more negative pitching moment coefficient.

Flow analysis on the ventral gap of a paper airplane

2020 ◽  
pp. 095440622094607
Author(s):  
Min Chang ◽  
Xiaoyu Feng ◽  
Yang Zhang ◽  
Xu Zhang ◽  
Junqiang Bai
Keyword(s):  
Delta Wing ◽  
Lift Coefficient ◽  
Flow Analysis ◽  
Aerodynamic Characteristics ◽  
Micro Aerial Vehicle ◽  
Moment Coefficient ◽  
Aerial Vehicle ◽  
Paper Airplane ◽  
The One ◽  
Flow Vortex

It is a challenging work to design micro aerial vehicle with great aerodynamic performance because the tiny wingspan at low-Reynolds-number cannot provide lift efficiently. The aerodynamic configuration of a classic delta-wing paper airplane is investigated in the present work with numerical method to discover its potential for micro aerial vehicle designs. Furthermore, the effect of the ventral gap on the aerodynamic characteristics of the paper airplane is investigated herein. The stall angles of attack reach 37.5° and 40°, respectively, for ventral opened configuration and the closed one, and the maximum lift coefficient reaches 1.49 and 1.46. The ventral-opened configuration has negative pitching moment coefficient (−0.01431) even at 37.5° while the closed one has a positive coefficient (0.01402). The reason may be the gap leads to a strong back-flow vortex before the trailing edge in the ventral gap which produces a strong nose-down moment. Generally, the ventral gap improves lift and dramatically influences the longitudinal stability compared with the one without it.

Aerodynamic Characteristics Prediction via Artificial Hair Sensor and Feedforward Neural Network

2015 ◽  
Author(s):  
Kaman Thapa Magar ◽  
Gregory W. Reich ◽  
Matthew R. Rickey ◽  
Brian M. Smyers ◽  
Richard V. Beblo
Keyword(s):  
Neural Network ◽  
Lift Coefficient ◽  
Unsteady Aerodynamics ◽  
Aerodynamic Characteristics ◽  
Stream Velocity ◽  
Sensors And Actuators ◽  
Local Flow ◽  
Distributed Sensors ◽  
Moment Coefficient ◽  
Hair Sensors

Fly by feel is a concept in which distributed sensors and actuators are integrated on an aerial system for state awareness or sensation of the environment, and make use of distributed control to increase the system maneuverability, stability and safety. Artificial hair sensors are good candidates as sensors for the fly by feel concept because they are lightweight, have low manufacturing costs and can easily be integrated on the surface of air-vehicle without affecting the flow. We investigate an application of artificial hair sensors considering its capability of measuring the local flow velocity combined with a Feedforward Artificial Neural Network to predict the aerodynamic quantities such as lift coefficient, moment coefficient, angle of attack and free-stream velocity in real-time. These quantities, when combined with the physical and unsteady aerodynamics parameters, will make a framework for designing and implementing an active controller for gust alleviation in a pitch and plunge airfoil system.

scholarly journals Experimental Determination of the Impact of Floats on the Aerodynamic Characteristics of an OSA Model in Symmetric Flow

2021 ◽  
Vol 12 (1) ◽  
pp. 41-58
Author(s):  
Michał FRANT ◽  
Stanisław WRZESIEŃ ◽  
Maciej MAJCHER
Keyword(s):  
Drag Coefficient ◽  
Aerodynamic Drag ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Symmetric Flow ◽  
Aerodynamic Drag Coefficient ◽  
The Impact ◽  
Drag Ratio ◽  
Lift To Drag Ratio

This paper presents the results of experimental determination of the impact of floats on the aerodynamic characteristics of an OSA model in symmetric flow. The studies have been performed in the low-speed wind tunnel at the Military University of Technology (MUT, Warsaw, Poland). The aircraft model was examined at the dynamic pressure q = 500 Pa in the following angle of attack range = -2828. The investigations have been performed for an aircraft model under plain configuration with floats and without floats. The influence of elevator and flap inclination on the aerodynamic characteristics of the model has also been analysed. The obtained values of aerodynamic drag coefficient, lift coefficient, pitching moment coefficient and lift-to-drag ratio have been presented in the form of tables and graphs. The studies performed demonstrated that the use of floats causes the increase of aerodynamic drag coefficient CD, maximum lift coefficient CLmax as well as critical angle of attack cr. The decrease of lift-to-drag ratio has also been observed. Its value in the case of the model with floats was up to 20% lower than in the model without floats. The studies also showed that the model equipped with floats had a lower longitudinal static stability margin than the model without floats.

scholarly journals Optimal cutting and prediction of assortment yields before and during tree felling

2019 ◽  
Author(s):  
А.С. Торопов ◽  
А.Н. Соловьев
Keyword(s):  
Mathematical Model ◽  
Exhaustive Search ◽  
Maximum Volume ◽  
New Approach ◽  
Optimum Cutting ◽  
Sexual Part ◽  
Determination Of Parameters ◽  
The Mathematical Model

В настоящей статье рассматривается новый подход к проблеме оптимального раскроя и прогнозирования выхода сортиментов до и в процессе валки деревьев. Авторы предлагают и теоретически обосновывают рациональный раскрой пиловочной части дерева по критерию максимального объемного выхода пиловочника в стоимостном выражении. В работе приведена математическая модель определения параметров половой части дерева на основе аллометрического метода исследований предмета труда и оптимального раскроя и прогнозирования выхода сортиментов до и в процессе валки деревьев с использованием метода исчерпывающего поиски и методы ветвей и границ. In this article new approach to a problem of optimum cutting and forecasting of an exit of assortments to and in process rolls of trees is considered. Authors offer and theoretically prove rational cutting of a pilovochny part of a tree by criterion of the maximum volume exit of sawlog in value terms. In work the mathematical model of determination of parameters of a sexual part of a tree on the basis of anallometrichesky method of researches of an object of the labor and optimum cutting and forecasting of an exit of assortments to and is given in process rolls of trees with use of a method exhaustive search and methods of branches and borders.

scholarly journals Aerodynamic Design of a Tailless Aeroplan

10.14311/268 ◽  
2001 ◽  
Vol 41 (4-5) ◽  
Author(s):  
J. Friedl
Keyword(s):  
Reynolds Numbers ◽  
Aerodynamic Characteristics ◽  
Strength Analysis ◽  
Aerodynamic Design ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Analysis And Design ◽  
Moment Coefficient ◽  
Wing Geometry ◽  
Design Requirements

The paper presents an aerodynamic analysis of a one-seat ultralight (UL) tailless aeroplane named L2k, with a very complicated layout. In the first part, an autostable airfoil with a low moment coefficient was chosen as a base for this problem. This airfoil was refined and modified to satisfy the design requirements. The computed aerodynamic characteristics of the airfoils for different Reynolds numbers (Re) were compared with available experimental data. XFOIL code was used to perform the computations. In the second part, a computation of wing characteristics was carried out. All calculated cases were chosen as points on the manoeuvring and gust envelope. The vortex lattice method was used with consideration of fuselage and winglets for very complicated wing geometry. The PMW computer program developed at IAE was used to perform the computations. The computed results were subsequently used for structural and strength analysis and design.

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.

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