Experimental and Numerical Study of the Effect of Varying Sinusoidal Bumps Height at the Leading Edge of the NASA LS ( 1 )-0413 Airfoil at Low Reynolds Number (original) (raw)
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The effect of leading edge tubercle geometry on the performance of different airfoils
2009
Results are presented of an experimental investigation on the effects of modification to the leading edge geometry of two NACA airfoils with different aerodynamic characteristics. The modification was inspired by the humpback whale flipper, which has rounded tubercles on its leading edge resembling the shape of a sine curve. Force measurements on both modified and unmodified 2-D airfoils show that tubercles are more beneficial for the NACA 65-021 airfoil than the NACA 0021 airfoil. Also, for smaller amplitude tubercles, the modified NACA 65-021 airfoil outperforms its unmodified equivalent for most angles of attack. Hydrogen-bubble visualisation was used to identify characteristic features of the flow for airfoils with tubercles. It appears that the velocity behind the troughs is greater than behind the tubercles themselves at the leading edge. Downstream from the leading edge, the flow from behind the peaks seems to be entrained into this region, giving rise to the formation of stream-wise vortices.
Numerical investigation of a modified NACA-0018 Airfoil using Bumpy Profile at Low Reynolds Number
International Journal of Advance Research, Ideas and Innovations in Technology, 2020
Flow separation is one of the major problems affecting the performance of all airfoils under a high angle of attack. Several passive flow mechanisms have been investigated to limit this phenomenon and improve the aerodynamic efficiency of the airfoil by increasing the lift force while decreasing the drag force associated with it. This study investigates the application of surface bumps over both the suction and pressure sides of the NACA-0018 airfoil at low Reynolds number of 500,000. The bump shapes resemble the shape of the Hawk which does not show a smooth profile in nature. The bumps are introduced in the form of sine waves with different amplitudes and periods. Bumps on each side have been investigated separately, the optimum amplitude and period are determined, the two optimum parameters were joined together forming a new airfoil shape. It was found that this approach limits separation at the stall angle and reduces the drag force as a result of the bumps on the suction side. ...
EFFECT OF LEADING EDGE TUBERCLES ON AIRFOIL PERFORMANCE
This thesis provides a detailed account of an experimental investigation into the effects of leading edge sinusoidal protrusions (tubercles) on the performance of airfoils. The leading edge geometry was inspired by the morphology of the Humpback whale flipper, which is a highly acrobatic species. The aim of this study is to investigate the potential advantages and disadvantages of incorporating tubercles into the leading edge of an airfoil. Specific parameters have been varied to identify an optimum tubercle configuration in terms of improved lift performance with minimal drag penalties.
Performance Variations of Leading-Edge Tubercles for Distinct Airfoil Profiles
AIAA Journal, 2011
An experimental investigation has been undertaken to determine the influence of sinusoidal leading-edge protrusions on the performance of two NACA airfoils with different aerodynamic characteristics. Force measurements on full-span airfoils with various combinations of tubercle amplitude and wavelength reveal that when compared to the unmodified equivalent, tubercles are more beneficial for the NACA 65-021 airfoil than the NACA 0021 airfoil. It was also found that for both airfoil profiles, reducing the tubercle amplitude leads to a higher maximum lift coefficient and larger stall angle. In the poststall regime, however, the performance with largeramplitude tubercles is more favorable. Reducing the wavelength leads to improvements in all aspects of lift performance, including maximum lift coefficient, stall angle, and poststall characteristics. Nevertheless, there is a certain point at which further reduction in wavelength has a negative impact on performance. The results also suggest that tubercles act in a manner similar to conventional vortex generators.
The present paper concerns the developing of a new airfoil with spherical leading-edge tubercles. The investigation is based on numerical simulation of the effect of tubercles on the flow characteristics around the airfoil. The diameter of each tubercle is 0.1 C, where C is the airfoil chord. The spanwise distance between the centerlines of two adjacent tubercles is 0.2 C. The NACA0012 profile, which represents the humpback flipper and is commonly used in many aerodynamic (e.g., wind turbines) and hydrodynamic applications, was utilized in this work. A wide range of angle of attack was tested; from 0 o to 25 o . The values of Reynolds number ranged between 65,000 and 1,000,000. The standard k-ε model was used as the turbulence modeling technique. The numerical scheme was validated using the well-known results of the standard NACA0012 profile (without tubercles). The results cover pressure distributions, streamline patterns, and lift and drag coefficients. Useful discussions and fruitful conclusions are recorded.
Journal of Academic Research, 2024
Article information This article seeks to numerically analyze the aerodynamic performance of the NACA-0015 airfoil blade, with a focus on examining the effects of varying the angle of attack on lift, drag, and stall characteristics. The design of an airplane's wing is critical for maximizing lift while minimizing drag, both of which are regulated by adjusting the angle of attack during flight. To explore these dynamics, Computational Fluid Dynamics (CFD) analysis is employed using ANSYS software, particularly its FLUENT tool, to simulate fluid flow around the airfoil. The airfoil geometry, with a chord length of 0.06 meters and a span of 0.25 meters, is modeled in ANSYS Design Modeler. The CFD simulations are performed using the Realizable k-epsilon turbulence model, analyzing angles of attack ranging from 0° to 18° under low Reynolds numbers (6×10 4 to1.6×10 5). Through this comprehensive approach, the study provides a wider understanding of the flow characteristics over the NACA-0015 airfoil, contributing to the precise knowledge of airfoil performance in aviation applications.
Influence of Spherical and Pyramidical Dimples and Bumps on Airfoil Performance in Subsonic Flow
Journal of Aerospace Technology and Management, 2021
In this study, surface features such as dimples and bumps are introduced to the surface of a NACA 0012 airfoil to study their effect on boundary layer separation, particularly at high angles of attack. Six modified airfoils were designed with dimples and bumps of spherical and pyramidical shapes. A computational fluid dynamics (CFD) analysis was conducted on these models at subsonic flow using Ansys Fluent. The analysis used the Shear Stress Transport k-ω turbulence model at a varying angle of attack (AOA) from 0 to 15°. The velocity contours and streamlines were generated. Also, the lift coefficient, drag coefficient and the lift-to-drag performance ratio were computed and analyzed. The results showed that all surface modifications led to delayed flow separation and flow recirculation. All surface modification also resulted in a decrease in drag at 15°. All designs, except pyramidical protrusions, increased the lift-to-drag ratio (L/D) performance at 15°. It was found that dimples are better than bumps and spherical features are better than pyramidical ones.
Tubercles Effect on a Wing Performance for NACA 634-421 Aerofoil
International Journal of Science and Engineering Applications, 2020
Humpback whales have a morphological structure on the leading edge of their flippers that provide them with the capability of extreme manoeuvrability. Inspired by nature, tubercle design has been incorporated in wing-like structures such as wind turbines, marine propellers, etc. The idea of tubercles was studied by P Watts and F E Fish to develop their turbine blades and showed that wind farms can produce up to 20% more power with less wind. The purpose of this study was to see how the performance of a finite wing is affected due to the geometrical modification. To understand the effect of tubercles, various parameters are being measured and compared. A Baseline model and model with Tubercles are being tested with a 6 digit NACA 634-421 cambered airfoil, similar to that of the flipper of the Humpback Whale. Tubercles of various wavelength and amplitudes are taken to analyse and study various aerodynamic characteristics. Preliminary analysis was carried out in XFLR for baseline model...
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.