Aerodynamic characteristics of low Reynolds number airfoils (original) (raw)
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A Study of Impacts of Airfoil Geometry on the Aerodynamic Performance at Low Reynolds Number
International Journal of Mechanical Engineering and Robotics Research
The aerodynamic performance of airfoils has been studied in several studies; however, the performance is highly relying on the airfoil geometry and the flow characteristics such as the flow type (laminar or turbulent) and Reynolds number. This paper focuses on understanding the aerodynamic performance of airfoils in a low-speed environment (low Reynolds number) versus the airfoil geometry. This paper would be a guide to the airfoil design and optimization processes toward the design target under similar flow conditions. Therefore, several parameters of the airfoil geometry, such as maximum thickness, maximum camber, their location, and reflex angle were studied in a low Reynolds number range from 0.3×10 6 to 0.8×10 6. Three airfoil parameterizations, NACA 4-digit, PARSEC, and Bezier curve, were utilised to generate the airfoil coordinates for different studied parameters. A twodimensional aerodynamic solver, XFOIL, was used to evaluate the aerodynamic performance of the airfoils. The results show that varying the airfoil geometry results in a noticeable change in the lift, drag, and moment coefficients. Also, as expected, increasing the Reynolds number has resulted in a good performance.
A Numerical Study of the Effects of Aerofoil Shape on Low Reynolds Number Aerodynamics
Proceedings of the Eighth International Conference on Engineering Computational Technology, 2000
A numerical study of the effects of airfoil shape on low Reynolds number aerodynamics is presented. The large-eddy simulations are performed with 6 th-order compact finite difference scheme and 10 th-order low pass filter, and 2 nd-order backward implicit time integration with inner iterations. Systematic numerical excesses show the feasibility of the current simulations to predict flow fields around fixed-wing configurations involving a laminar separation and laminar-to-turbulence transition at low Reynolds number. At the Reynolds number of 2.3×10 4 , two types of thin and asymmetric airfoils as a target airfoil shape of micro-size air vehicle are considered. The results show that the airfoil cross section affects the formation of a laminar separation bubble and the transition to turbulence in the three-dimensional flow around the wings at low angle of attack and hence significant influence on the aerodynamic performance.
Aerodynamics of a Modified High-Lift Low Reynolds Number Airfoil: Preliminary Analysis
International journal emerging technology and advanced engineering, 2022
Airfoil selection is a crucial phase in the design of a small unmanned fixed-wing aircraft to allow a minimum size and weight of the lifting surfaces. The present study analyzesairfoils to be used in low operating Reynolds number unmanned aerial vehicles (UAV) using XFLR5 software, which was validated against wind tunnel data. Three baseline airfoils were investigated, namely NACA4412, Miley M06-13-128 and Selig S1223. The best performing airfoils are then modified using the inverse airfoil design method to improve their performance in cruising flight. The modified airfoil resulted in larger leading edge radius and slightly thicker chord of the airfoil compared to the baseline airfoil. In general, the modified airfoil showed an improvement in stall characteristic, lift and drag coefficients in the post-stall regime, and a lower magnitude of moment coefficient for almost all investigated angles of attack compared to the baseline airfoil.
CFD Letters, 2022
The Micro Aerial Vehicles (MAVs) operate at a critical range of low Reynolds number (Re). The implementation of the low (Re) aerodynamics for MAVs has brought interest into the study of high-lift low Re airfoils. Such investigations may bring new insight into the aerodynamic performance of MAVs flights. The aim of the current investigation is to exam different numerical methods in the aerodynamics prediction of high-lift low Reynolds number S1223 airfoil. For that purpose, the Spallart Allmaras (S-A), two equations SST K-ω and the four equations transition γ-Reθ SST turbulence models were used. Results revealed that the SA turbulence model can predict the pre-stall low angles of attack and provides a good agreement with experimental data and XFOIL results. Whereas the two-equation model SST-enhanced K-ɷ and the transition SST models predict better the unsteadiness of the stall behaviour. XFoil accurately predicts the highest lift coefficient, even if it occurs at a lower angle of at...
Contributions to the prediction of low Reynolds number aerofoil performance
1987
The dominant aspects of low Reynolds number flows are identified and their relevance to aerofoil performance discussed A method for assessing two-dimensional aerofoil performance characteristics, including trailing edge and gross laminar separation, is developed along with a subsidiary direct boundary layer calculation scheme capable of accounting for short laminar separation bubbles The constituent parts of the performance prediction scheme, which consists a vortex panel method with boundary layer corrections and an inviscidly modelled wake, are described in some detail Predictions obtained for both laminar and turbulent separation are also presented For laminar separation, an inviscid Wake Factor Increment correlation is developed to account for the effects of the free laminar shear layers Generally, the predictions of lift and pitching moment may be considered to be within the experimental error, but where this is not the case the applicability of the modelling technique is discu...
Investigation of Airfoil Design and Analysis
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022
In this project "Aerofoil Design and Analysis" an attempt has made to make a complete study on lift and drag coefficient of various aerofoil sections using CFD. The primary goal of this project is to learn and analyse the aerodynamic performance of wings. The objective of this study is to improve aerofoil design using the software CATIA, And Fluent Analysis using the software ANSYS. Aerofoil is a principal part of any airplane construction. How much lift force and drag force is sufficient to balance the weight of the plane is decided by the aerofoil. Aerofoils are basically divided into two categories-they are Asymmetrical and Symmetrical aerofoils. Based on their drag and lift coefficient's variation with angle of attack, stall angle of attack and magnitude of the coefficients they are divided. Here the NACA aerofoil is modified by adding dimples on the upper half of the wing and compared with the simple one. The comparison is made on different speed and pressure on the wing and the coefficient of lift and drag. I.
Various Approaches to Increase the Aerodynamic Efficiency for Airfoils at Low Reynolds Number Flows
From the past many decades, many researches have worked on different airfoils for getting the efficient lift. Lift and drag are the two factors on ehich aerodynamic efficiency is based on. These can be determined by the pressure distibution over the airfoil.. Pressure distribution depends on the free stream velocity of air around the airfoil. At low Reynolds number, velocity of flow of an airfoil is lower then the velocity of flow at high Reynolds number, which is a reason for the decrease in the lift. So, to increase the performance of airfoil at low Reynolds number, there are some methods involved like airfoil shaping, boundary layer control and also by increasing the flow speeds over the blades. In the present work, an airfoil is designed by taking the computational approach and lift variations are studied for the airfoil at low Reynolds numbers. Then the lift variations are again studied at low Reynolds number by involving the above mentioned methods. Viscous flow analysis is us...
Ultra-Light Aircraft Airfoil Design and Characteristics
The aim of this research was to find out whether it is possible to obtain a new airfoil design for an ultra-light aircraft, geometrically in which the aerodynamic characteristics are intermediate between two known airfoils (NACA 652-415 and NLF (1)-0215). For this purpose, a geometric design philosophy has been applied as a first step and here it's described; Using CAD software (CATIA) reference airfoils (NACA 652-415 and NLF (1)-0215.) are drawn geometrically at the same coordinates, from the same starting point and at the same scale. In total, four new airfoils configurations were generated, by drawing the required coordinates of the new possible models between the coordinates of the two mentioned airfoils. CFD simulations were applied to new and reference airfoils using fluent to verify aerodynamic characteristic. The simulation will be done at the same conditions corresponding to angle of attack, velocity and Reynolds numbers. A comparison of the obtained characteristic of new airfoils also be done with the available data for the reference airfoils. The results obtained from this study will be tabulated and graph of the relationship between the Lift to the Angles of Attack will be plotted. The angle of attack as a variable varied from-14o to +14o. Results show a useful method that enables to create new airfoils, geometrically, and it also enables to control the aerodynamic characteristics of the aircraft, so that it can provide a large number of options among the reference airfoils. Here, the designer is able to choose the characteristics with high accuracy so that they could fit the purpose of the designed aircraft, based on the aerodynamic characteristics of known airfoils, because the characteristics of the new airfoils are intermediate between the references. And whenever the geometric points of the new one is close to the points of the reference one, their characteristics approach these of the reference airfoil
Viscous-inviscid analysis of transonic and low Reynolds number airfoils
AIAA Journal, 1987
A method of accurately calculating transonic and low Reynolds number airfoil flows, implemented in the viscous-inviscid design/analysis code ISES, is presented. The Euler equations are discretized on a conservative streamline grid and are strongly coupled to a two-equation integral boundary-layer formulation, using the displacement thickness concept. A transition prediction formulation of the e 9 type is derived and incorporated into the viscous formulation. The entire discrete equation set, including the viscous and transition formulations, is solved as a fully coupled nonlinear system by a global Newton method. This is a rapid and reliable method for dealing with strong viscous-inviscid interactions, which invariably occur in transonic and low Reynolds number airfoil flows. The results presented demonstrate the ability of the ISES code to predict transitioning separation bubbles and their associated losses. The rapid airfoil performance degradation with decreasing Reynolds number is thus accurately predicted. Also presented is a transonic airfoil calculation involving shock-induced separation, showing the robustness of the global Newton solution procedure. Good agreement with experiment is obtained, further demonstrating the performance of the present integral boundary-layer formulation.
Design and Analysis of Airfoil Using Simulation Techniques
An airfoil is the shape of a wing or blade or sail as seen in cross-section. An airfoil-shaped body moved through a fluid produces an aerodynamic force. The airfoil designing is a critical task due to various dependent variables in design process. This article deals with simulation of new airfoil section design and comparing it with a standard baseline airfoil. The calculations of lift force are done for six cases for varying altitude, constant rotor and air stream velocity. The conclusions are drawn from the simulated results obtained after analysis which will be useful in design of airfoil.