Lift Coefficient Research Papers - Academia.edu (original) (raw)

Designing an aircraft involves a lot of stages, however, airfoil selection remains one of the most crucial aspects of the design process. The type of airfoil chosen determines the lift on the aircraft wing and the drag on the aircraft... more

Designing an aircraft involves a lot of stages, however, airfoil selection remains one of the most crucial aspects of the design process. The type of airfoil chosen determines the lift on the aircraft wing and the drag on the aircraft fuselage. When a potential airfoil is identified, one of the first steps in deciding its optimality for the aircraft design requirements is to obtain its aerodynamic lift and drag coefficients. In the early stages of trying to select a candidate airfoil, which a whole part of the design process rests on, the conventional method for acquiring the aerodynamic coefficients is through Computational Fluid Dynamics Simulations (CFDs). However, CFD simulation is usually a computationally expensive, memory-demanding, and time-consuming iterative process; to circumvent this challenge, a data-driven model is proposed for the prediction of the lift coefficient of an airfoil in a transonic flow regime. Convolutional Neural Networks (CNNs) and Multi-Layer Perceptro...

The enhancement of the aerodynamic characteristics of the NACA0012 airfoil is studied numerically. ANSYS Fluent is used to simulate the airfoil's performance by applying certain surface modifications in the form of dimples and... more

The enhancement of the aerodynamic characteristics of the NACA0012 airfoil is studied numerically. ANSYS Fluent is used to simulate the airfoil's performance by applying certain surface modifications in the form of dimples and protrusions. Different shapes were used, namely, semicircular, v-shaped and square. Analysis has been done on an airfoil of 1m chord length with these modifications, which were implemented on the upper surface of a twodimensional airfoil model and placed at 75% of chord length. A comparative study of surfacemodified airfoil models was done to investigate lift and drag for a constant at Re = 3.0E6 at various angles of attack and compare them with smooth airfoils. The results reveal that the aerodynamic characteristics were improved by applying surface modifications, and the flow separation on the airfoil can be delayed by using dimples and protrusions on the upper surface. It was found that the semicircular dimples and v-shaped bumps have the best aerodynamic enhancement, where the lift coefficient was improved by 11% and 9% compared to smooth airfoils, respectively, while the drag coefficients were reduced by 3% for both shapes. Also, based on these surface-modified airfoil analyses, the stall angle was increased by two degrees. In comparison, the semicircular dimples are more suitable for enhancing the performance characteristics of airfoils.

In order to shorten product design time, engineers need to create high quality meshes within a few days or hours. Newer automated techniques have been published to tackle this need, the Cartesian Cut Cell is one of them. This study is... more

In order to shorten product design time, engineers need to create high quality meshes within a few days or hours. Newer automated techniques have been published to tackle this need, the Cartesian Cut Cell is one of them. This study is focused on the effect of different Cut Cell meshing strategies on the accuracy of aerodynamic performance predictions. The method can be described as a methodology in which Cut Cells are applied to the geometry utilizing a process involving rectangular/hexagonal cells on a regular lattice cutting through the geometry. The Cut Cell meshing is a general purpose designed for ANSYS FLUENT, making use of Workbench to construct the airfoil shape and the mesh. The results obtained for NACA-0012 are computed using two models available in ANSYS FLUENT, namely the Eq. 2 k-ω SST and the Eq. 3 k-kl-ω models. The three-dimensional numerical simulations were created for steady incompressible flow around NACA-0012 shape. Lift coefficient, Boundary layer thickness...

When a critical angle of attack of an airfoil is exceeded the boundary layer flow separation occurs (stall point). The lift coefficient of the airfoil rapidly decreases and a drag coefficient increases. The stall could lead to an... more

When a critical angle of attack of an airfoil is exceeded the boundary layer flow separation occurs (stall point). The lift coefficient of the airfoil rapidly decreases and a drag coefficient increases. The stall could lead to an autorotation of an aircraft and to fast reduction of an altitude. To prevent or postpone flow separation around airfoils many researches using DBD actuators were performed [3–5]. In this paper an innovative multi-DBD plasma actuator with floating inter-electrode is presented. The experimental results showed that this actuator could be attractive for aerodynamic applications, in particular for the leading edge flow separation control around NACA0012 airfoil model.

Designing an aircraft involves a lot of stages, however, airfoil selection remains one of the most crucial aspects of the design process. The type of airfoil chosen determines the lift on the aircraft wing and the drag on the aircraft... more

Designing an aircraft involves a lot of stages, however, airfoil selection remains one of the most crucial aspects of the design process. The type of airfoil chosen determines the lift on the aircraft wing and the drag on the aircraft fuselage. When a potential airfoil is identified, one of the first steps in deciding its optimality for the aircraft design requirements is to obtain its aerodynamic lift and drag coefficients. In the early stages of trying to select a candidate airfoil, which a whole part of the design process rests on, the conventional method for acquiring the aerodynamic coefficients is through Computational Fluid Dynamics Simulations (CFDs). However, CFD simulation is usually a computationally expensive, memory-demanding, and time-consuming iterative process; to circumvent this challenge, a data-driven model is proposed for the prediction of the lift coefficient of an airfoil in a transonic flow regime. Convolutional Neural Networks (CNNs) and Multi-Layer Perceptro...

In many cases, a set of obstacles, such as bridge piers and abutments, are located in the river waterway. Bridge piers disrupt the river’s normal flow, and the created turbulence and disturbance causes diversion of flow lines and creates... more

In many cases, a set of obstacles, such as bridge piers and abutments, are located in the river waterway. Bridge piers disrupt the river’s normal flow, and the created turbulence and disturbance causes diversion of flow lines and creates rotational flow. Geometric shape and position of the piers with respect to flow direction and also the number of piers and their spacing are effective in changing the river-flow conditions, such as the formation of vortices, their breakdown and hydrodynamic forces exerted on the piers. This article has been performed by applying the two-dimensional, open-source, OpenFOAM software. For this purpose, after selecting the grid size in GAMBIT software, different pier shapes were examined , considering different Reynolds numbers, and formation of the flow pattern, Strouhal number, vortex magnitude, and drag and lift coefficients for each pier shape were specified. Results for three different pier shapes indicated that in Reynolds number of 200, the highes...

The use of rear spoilers on MPV vehicles is often used by the public to get an aerodynamic vehicle body design. The understanding of the function of using rear spoiler accessories in the community is still low, so it is necessary to study... more

The use of rear spoilers on MPV vehicles is often used by the public to get an aerodynamic vehicle body design. The understanding of the function of using rear spoiler accessories in the community is still low, so it is necessary to study the characteristics of air flow in aerodynamics. This study aims to determine the flow characteristics of MPV type vehicles with standard and longer rear spoiler installation. This research was conducted in a Subsonic Open Circuit wind tunnel with test section dimensions (365 x 365 x 1250) mm. The flow characteristics were observed experimentally that passed through the model surface resembling the first generation Toyota Avanza MPV with a ratio of 1:20 with variations of the standard and longer rear spoiler installation. Measurement of the flow velocity profile behind the vehicle test model was carried out at an X/L ratio of 0.32 from the leading edge with a speed adjusted to the Reynolds number value of 1.96 x 105. The flow characteristic observe...

The current paper presents the tolerance and parameter design for robust wind turbine. By utilizing the traditional Taguchi method along with its extensions, there is a way of designing a robust wind turbine by considering multiple... more

The current paper presents the tolerance and parameter design for robust wind turbine. By utilizing the traditional Taguchi method along with its extensions, there is a way of designing a robust wind turbine by considering multiple objectives, constraints and design variables. The concept of design of experiment (DOE) i.e.; Taguchi Method is used to evaluate the constrained and unconstrained problems for the optimization. The current work produces an inexpensive and simpler approach for robust vertical axis wind turbine. DOE (Taguchi Method) of L-9 Orthogonal Array having four parameters along with their three levels i.e; type of NACA aerofoil, Reynolds number, Mach number and Angle of attack are utilized for the optimization and to derive the corresponding optimal values of CL, CD and CP. The parameters like coefficient of lift, drag and power for the wind turbine was determined by Q-Blade software, which is use for designing of wind turbine blades. From the obtained results the in...

Possible interference effects of the wind tunnel walls play an important role especially for measurements in closed-wall test sections. In this study, a numerical analysis of two-dimensional subsonic flow over a NACA 0012 airfoil at... more

Possible interference effects of the wind tunnel walls play an important role especially for measurements in closed-wall test sections. In this study, a numerical analysis of two-dimensional subsonic flow over a NACA 0012 airfoil at different computational domain heights, angles of attack from 0o to 10o, and operating Reynolds number of 6×106 is presented. The work highlights the role of computational fluid dynamics (CFD) in the investigation of wind tunnel wall effect on lift curve slope correction factor (Ka). The flow solution is obtained using Ansys Fluent software by solving the steady-state continuity and momentum governing equations combined with turbulence model k-v shear stress transport (SST-K?). The numerical results are validated by comparing with the available experimental measurements. Calculations show that the lift curve slope correction results are very close to the published data.

A nose cone is the conically shaped forward most section of a rocket, guided missile or aircraft, designed to modulate oncoming airflow behaviours and minimize drag. In this paper, the authors analysed by means of a computational... more

A nose cone is the conically shaped forward most section of a rocket, guided missile or aircraft, designed to modulate oncoming airflow behaviours and minimize drag. In this paper, the authors analysed by means of a computational procedure the influence of varying the angle of attack for shapes of rocket nose cones in each of them, with this analysed and calculated the values of the, coefficient of lift and the coefficient of drag generated by our nose cones having as a working parameter in subsonic medium ranging from a Mach 0.03 to approximately 0.50, considering standard conditions for temperature and pressure. Drag and Lift both are aerodynamic forces which need to be calculated for cones. Objects with every kind of shapes experience a significant magnitude of Cl and Cd from airflow with the use of the ANSYS platform based on the CFD Fluent method it was possible to measure behaviour in the 3 shapes of cones and thus analyse the different contours. We showed the variation of pre...

The effect of miniflaps for increasing the L/D ratio and the lift coefficient has been studied on airliners as well as on UAV-s and wind turbines. For sailplanes the lift when Cl > 1.0 is of main interest. As the maximum wing loading... more

The effect of miniflaps for increasing the L/D ratio and the lift coefficient has been studied on airliners as well as on UAV-s and wind turbines. For sailplanes the lift when Cl > 1.0 is of main interest. As the maximum wing loading of racing sailplanes reaches 60–62 kg/m2, it is necessary to achieve a high Cl max (1.7–1.8) in thermals. In this case the decrease in TAS caused by a high Cl max even compensates for the drop of the L/D ratio to a certain extent, as the climb speed will increase when the spiral flight radius diminishes in thermals. To bring the L/D to Cl > 1.0, a 2% chord miniflap at a 30° deflection angle was attached to the trailing edge of a Jantar-Standard 3 type sailplane wing (airfoil NN-8). In flight tests it was found that the miniflap increased the sailplane‘s Cl max to 1.35–1.66, i.e. by 23% (Re 1.0–0.92×106). At the same time the L/D ratio Cl increased by over 1.0. Especially good L/D improvement was noted with Cl at 1.13–1.19. In thermal Cl of 1.57–1....

This project was based on the principle of designing, simulating and developing an inexpensive, aerodynamically efficient and regular class electric powered RC aircraft. This prototype was designed to have the maximum strength to weight... more

This project was based on the principle of designing, simulating and developing an inexpensive, aerodynamically efficient and regular class electric powered RC aircraft. This prototype was designed to have the maximum strength to weight ratio with minimum drag coefficient (and highest lift coefficient). Moreover, all constraints provided by SAE International competition were followed. The investigation was conducted for the complete airplane and for wing optimization. The model was numerically investigated with ANSYS Fluent 16.1 through the SST K-Omega turbulence model at Reynolds number of 360,000. Once the results were obtained, model and result verification were done by wind tunnel test to validate the data. It was concluded that the airplane with 45° winglet has the highest lift force with minimal drag and 45° winglet was further modified with rectangular and triangular vortex generators in order to further enhance its aerodynamic efficiency for a range of Angle of Attacks (AOA).

High Reynold number (Re) viscous flow is one of the most typical characteristics of an advancing ship. Therefore, the wake flow after the ship hull is very complex and it will strongly affect the propulsion performance. RANS approach and... more

High Reynold number (Re) viscous flow is one of the most typical characteristics of an advancing ship. Therefore, the wake flow after the ship hull is very complex and it will strongly affect the propulsion performance. RANS approach and hybrid LES/RANS methods are very popular in the contemporary research of ship flows, with the consideration of less computational cost compared with LES. In the present work, several numerical models, i.e. standard Shear Stress Transport (SST) model for RANS, DES, Delayed DES (DDES) and Improved Delayed DES (IDDES) model are used to predict the viscous flows around a full block ship. Numerical computations are carried out by the in-house CFD solver naoe-FOAM-SJTU developed on OpenFOAM. The ship model Japan Bulk Carrier (JBC) is used in the present computations and the numerical setup is following the benchmark case in Tokyo 2015 CFD Workshop. Extensive experimental data including detailed wake flows through PIV measurements is available for the vali...

The lift force is one of the important factors in supporting the aircraft flying capabilities. The airplane has a section called the aircraft wing. In particular, the wing section of aircraft is called the airfoil. One of the efforts to... more

The lift force is one of the important factors in supporting the aircraft flying capabilities. The airplane has a section called the aircraft wing. In particular, the wing section of aircraft is called the airfoil. One of the efforts to increase the lift force is to make the flow of air fluid at the top of the airfoil more turbulent. Turbulent flow can attract momentum from the boundary layer, the result of this momentum transfer has energy that is more resistant to the adverse pressure gradient which can trigger the flow separation. Efforts that can be made to reduce separation flow and increase lift force are the addition of a turbulent generator on the upper surface of the airfoil, one type of turbulent generator is a vortex generator, a vortex generator can accelerate the transition from the laminar boundary layer to the turbulent boundary layer. This study was conducted with the aim of knowing the effect of the vortex generator on the aerodynamics of NACA-4412 using the computa...

Recently, lots of oscillating targets inspired from motions of some insects and birds have been applied extensively to many engineering applications. The aim of this work is to reveal the performance and detailed flow structures over the... more

Recently, lots of oscillating targets inspired from motions of some insects and birds have been applied extensively to many engineering applications. The aim of this work is to reveal the performance and detailed flow structures over the pitching corrugated hydrofoils under various working conditions, using the SST [Formula: see text] transition model. First of all, the lift coefficients of a smooth oscillating airfoil at different reduced frequency and pitching angles show a good agreement with the experiments, characterized by the accurate prediction of the light and deep stall. For the pitching corrugated hydrofoils, it shows that the mean lift coefficient increases with the pitching magnitude, but it has an obvious drop at high reduced frequency for the case with large pitching amplitude, which is mainly induced by the pressure modification on the surface with smooth curvature, depending on the oscillation significantly. In addition, the mean drag coefficient also indicates that...

There is an accelerating requirement for ocean sensing where autonomous vehicles can play an essential role in assisting engineers, researchers, and scientists with environmental monitoring and collecting oceanographic data. This paper is... more

There is an accelerating requirement for ocean sensing where autonomous vehicles can play an essential role in assisting engineers, researchers, and scientists with environmental monitoring and collecting oceanographic data. This paper is performed to develop a rigid sail for the autonomous sailing drone. Our study aims to numerically analyze the aerodynamic characteristics of curvy twin sail and compare it with wing sail. Because racing regulations limit the sail shape, only the two-dimensional geometry was open for an optimization. Therefore, this study’s first objective was to identify the aerodynamic performance of such curvy twin sails. Simultaneously, a secondary objective was to estimate the effect of the sail’s spacing and shapes. A viscous Navier-Stokes flow solver is used for the numerical aerodynamic analysis. The 2D aerodynamic investigation is a preliminary evaluation. The results have shown that the curvy twin sail designs have improved lift, drag, and driving force co...