Standard Airfoil Research Articles

Performance analysis of the airfoil-slat arrangements for hydro and wind turbine applications

Standard airfoils historically used for wind and hydrokinetic turbines had maximum lift coefficients of around 1.3 at stall angles of attack, which is about 12°. At these conditions, the minimum flow velocities to generate electric power were about 7 m/s and 2 m/s for the wind turbine and the hydrokinetic turbine cases, respectively. In this study, NACA4412-NACA6411 slat–airfoil arrangement was chosen for these two cases in order to investigate the potential performance improvements. Aerodynamic performances of these cases were both numerically and experimentally investigated. The 2D and 3D numerical analysis software were used and the optimum geometric and flow conditions leading to the maximum power coefficient or the maximum lift to drag ratio were obtained. The maximum lift to drag ratio of 24.16 was obtained at the optimum geometric and flow parameters. The maximum power coefficient of 0.506 and the maximum torque were determined at the tip speed ratios of 5.5 and 4.0 respectively. The experimental work conducted in a towing tank gave the power coefficient to be 0.47 which is about %7 lower than the numerical results obtained. Hence, there is reasonable agreement between numerical end experimental values. It may be concluded that slat-hydrofoil or airfoil arrangements may be applied in the design of wind and hydrokinetic turbines for electrical power generation in lower wind velocities (3–4 m/s) and current velocities (about 1 m/s).

Aerodynamic Performance Comparison of Airfoils by Varying Angle of Attack Using Fluent and Gambit

Any aircraft wing is the major component which will play vital role in the generation of lift and at different maneuvering moments throughout the flight. So to maintain this good maneuverability the aircraft wing has to undergo deferent deflections called angle of attack such that the high lift and low drag or vice versa can be settled in the flight. Taking this as the motivation the analysis was carried out on the standard wing airfoil comparing with new designed airfoil. Analyze the numerical simulation values like coefficient of lift, coefficient of Drag, Lift, Drag, and Energy parameters with wind tunnel data to predict accuracy for both the airfoils. Through the selected public literature standard airfoil data and designed airfoil data has been chosen, the geometry was created in the GAMBIT and also the meshing by selecting the suitable c-grid and rectangular grid for the better flow analysis in the FLUENT. The mesh file was imported into the FLUENT software there suitable boundary conditions and operating conditions are given for successful flow convergence. Finally analyzing these results are expecting to be best suitable for good aeromechanical features.

Numerical Analysis of a Modefid Airfoil for Wind Turbine

This paper presents a numerical analysis of new airfoil, TCB6612, and compared with respect to standard airfoil NACA4412 using them in wind turbine blade. The main objective of this work is to enhance the aerodynamic performance of airfoil by changing the geometry of the airfoil in order to increase the overall power output of the wind turbine. Two software, GAMBIT and FLUENT, are used in this work; GAMBIT is used to create modeling and meshing of the airfoils while FLUENT is used to simulate and analysis the airfoils. The analysis showed that the significant enhancement in aerodynamic performance for TCB6612 is occurred. It is found that value of Cd/Cl is decreased about 10.23%, the power coefficient is reached to 51.9%, and the power output is increased about 9.8%.

Aerodynamic Characteristics of a Deformable Membrane Aerofoil

In the paper, numerical and experimental study of low Reynolds number airflow around the deformable membrane airfoil (DMA) is presented. Simulations of a fluid-structure interaction between the fluid and the DMA were performed. In the experiment, the DMA model was made from a thin PVC sheet, which was wrapped around the steel rod at the leading and trailing edge. Measurements were performed in a wind tunnel at a chord Reynolds number of 85.7·103, over the angle of attack range from 0° to 15° and DMA shortening ratio from 0.025 to 0.150. Simulations were in an agreement with the experiment, since the average relative difference of coefficient of lift was smaller than 7.3%. For the same value of Reynolds number, DMA shows improved lift coefficient Cy= 2.18, compared to standard rigid airfoils.

Joint Experimental and Numerical Approach to Three-Dimensional Shock Control Bump Research

Previous studies of transonic shock control bumps have often been either numerical or experimental. Comparisons between the two have been hampered by the limitations of either approach. The present work aims to bridge the gap between computational fluid dynamics and experiment by planning a joint approach from the outset. This enables high-quality validation data to be produced and ensures that the conclusions of either aspect of the study are directly relevant to the application. Experiments conducted with bumps mounted on the floor of a blowdown tunnel were modified to include an additional postshock adverse pressure gradient through the use of a diffuser as well as introducing boundary-layer suction ahead of the test section to enable the in-flow boundary layer to be manipulated. This has the advantage of being an inexpensive and highly repeatable method. Computations were performed on a standard airfoil model, with the flight conditions as free parameters. The experimental and computational setups were then tuned to produce baseline conditions that agree well, enabling confidence that the experimental conclusions are relevant. The methods are then applied to two different shock control bumps: a smoothly contoured bump, representative of previous studies, and a novel extended geometry featuring a continuously widening tail, which spans the wind-tunnel width at the rear of the bump. Comparison between the computational and experimental results for the contour bump showed good agreement both with respect to the flow structures and quantitative analysis of the boundary-layer parameters. It was seen that combining the experimental and numerical data could provide valuable insight into the flow physics, which would not generally be possible for a one-sided approach. The experiments and computational fluid dynamics were also seen to agree well for the extended bump geometry, providing evidence that, even though the bump interacts directly with the wind-tunnel walls, it was still possible to observe the key flow physics. The joint approach is thus suitable even for wider bump geometries.

Optimal and Simulation of HAWT Blade S809

The object of this study to analysis of airfoil S809 blade with optimized condition and prepare 3D modeling when using Blade Element-momentum theory and Computational Fluid Dynamic theory. The Standard Airfoil Data using to optimized the blade parameter like twisting angle and chord length. The aerodynamic study and pressure contour study on blade with CFD and FEM analysis, but the systematic term of Euler's Equation, forces magnitude and direction and the velocity attack to the blade is to be a 4 degree of angle of attack. A blade acts much like an airplane wing, when the wind flow through blade and the pressure generation factor work to lifting the the blade. The Pressure gradient in upper and lower surface of blade is different which is cause the aerodynamic structure of blade. The simulation of wind turbine with large eddy and the equation use like Reynold-Average, Navier-Stokes and Direct Numerical Simulation.

STUDY ON AERODYNAMIC PERFORMANCE OF THE BIONIC AIRFOIL BASED ON THE SWALLOW'S WING

This paper demonstrates the design of the airfoil of small wind turbines, the bionic airfoil was inspired by the morphology of the swallow's extended wing. The wind tunnel tests on the bionic and standard airfoils NACA4412 were conducted, and the aerodynamic performances of the airfoils were numerically investigated. The results show that the bionic airfoil has better aerodynamic performance, the lift coefficient and lift-drag ratio are larger than those of the NACA4412; with the angle of attack increases, both the bionic and standard airfoils stall, but the stall characteristics of the bionic airfoil are better.

3d Analysis of Lift and Moment Adaptation via Control Surface Deployments on a 5 MW Wind Turbine Blade

This paper investigates the impact of deploying control surfaces on a model 5 MW offshore wind turbine blade. The wind turbine blade is modeled in 3D based on NREL's 5 MW wind turbine and incorporates varying airfoil shapes and structural twist along the blade length. Lift and aero-dynamic moment at various angle of attack settings are simulated and analyzed. Partial span-wise trailing-edge 3D control surfaces are modeled, simulated and analyzed at various control angles. Results depict the onset of stall around 22 degrees and a larger lift gain versus 10–15 degrees for standard 2D airfoils. Mid-flap controller enhances lift by a factor 2 and mitigates moment a factor of around 7 while end-flap controller enhances lift by a factor of around 1.024 and mitigates moment by a factor of around 2. The results and comparisons obtained serve as one of many instruments for gauging, designing, analyzing, and optimizing wind turbine systems.

Optimization Design of Airfoil Propellers of Modified NACA 4415 Using Computational Fluids Dynamics

Utilization of wind power in Indonesia is less attractive compared with utilization of conventional fuel. This is because the price of wind energy is not competitive when compared with fossil energy prices, and as a result of the implementation of energy pricing policy through subsidies. Before designing the Wind Energy Conversion System, simulation of computational fluid dynamics needs to be done in order for reducing designing time and cost. In this research, modeling and simulation work has been done to figure out the optimum aerodynamics coefficient of wind turbine blades at different Reynolds number. This blade is a modification of standard airfoil of NACA 4415. The aerodynamics coefficient of modify and standard airfoil is then compared. FLUENT software and Spalart-Allmaras Turbulent Model are used in this work. Based on the comparison of the coefficient of aerodynamic, modification NACA 4415 airfoil has better performance at Reynolds number of 4.1 x 104 to 2.5 x 105. The experiment results also showed that based on a numerical study of the modification NACA 4415 airfoil can be used as a basis for the establishment of wind turbine blades.

Utilization of Albizia Wood (<i>Albizia falcat</i>a) and Ramie Fibers as Wind Turbine Propeller Modification of NACA 4415 Standard Airfoil

Ramie fibers and albizia wood, which are abundantly available in Indonesia, were used in fabricating hybrid sandwich composite for wind turbine propeller. A prototype was fabricated by modification of NACA 4415 standard airfoil, intended for low speed wind and environmental friendly operations. Hand lay-up method was applied for fabrication of this hybrid composite with one and two layers of ramie fiber. Mean volume fiber fraction (vf) of one-layer and two-layer composite are 47,12% and 44,82%, respectively. The highest measured bending stress is 30.88 MPa for two-layer composite with modulus of elasticity 2.02 GPa and bending strain 1,795%. Microstructure of this hybrid composite is unchanged significantly after 5.5 months operation. With ultimate simplicity and low manufacturing cost, hand lay-up method is suitable for small scale production.

Hydrodynamics performance of hydrofoil-slat arrangements in 3D analysis

Standard airfoils historically used for wind and hydrokinetic turbines have the maximum lift coefficients of about 1.3 at the stall angle of attack, which is about 12°. At these conditions, the minimum flow velocities to generate electric power are about 7m/s and 3m/s for wind turbine and hydrokinetic turbine, respectively. The design optimization of the rotor is very important to maximize the power production. The performance of the rotor can be determined by various geometric and flow parameters. Using leading edge slat delays the stall up to an angle of attack with a maximum lift coefficient. Three dimensional analyses were conducted on the hydrofoil-slat arrangements, NACA2415–NACA22 and NACA4412–NACA6411, the range of the tip speed ratio from 3 to 7. For the first and second arrangements, the maximum efficiency of 0.45 and 0.501 were obtained at the tip speed ratio of 5.5. For these two arrangements, the efficiencies have the values about more than 0.4 over a relatively narrow and large range of the tip speed ratio respectively. The selection of the hydrofoil (or airfoil)-slat arrangements has important effect on the performance of the system. Thus, the hydrofoil (or airfoil)-slat arrangements can be applied in the design of wind and hydrokinetic turbines in lower wind and current velocities.

Computational analysis of the aerodynamic performance of a jet-flap airfoil in transonic flow

The needed shift in next generation aircraft design is expected to bring novel concepts for civil aviation as the jet-flap wing. The aircraft efficiency improvements with the jet-flap wing directs its use for future aircraft designs reinforced by the tendency for more synergistic systems as active flow control, boundary layer ingestion and distributed propulsion, making the jet-flap wing a very suitable option for the latter concept. The analysis carried out in this paper is aimed at the application of the jet-flap wing concept for manoeuvrability and cruise efficiency improvement of an airliner. A 2D computational model of a jet-flapped transonic airfoil is developed in order to assess the jet-flap wing technology for a commercial aircraft at cruise conditions. This paper provides an insight into the parameters that affect the performance of a jet-flap under various flight conditions. To do this, a general parametrical analysis is performed, studying numerically the influences of main flow parameters like Mach number, Reynolds number, angle of attack, jet deflection angle and jet thickness. Changes in pressure distribution and flow circulation around the airfoil yield strong modifications in lift and drag due to jet angle variation. Improvements are encountered in the performance of an airfoil with a jet-flap system compared with a standard airfoil with no jet. Enhancements in lift and reduction in drag, as well as an increase of the lift-to-drag ratio is possible with a proper combination of the jet deflection and the angle of attack of the airfoil. In summary, this paper shows the conditions under which the benefits of the jet-flapped wing, for lift enhancement and manoeuvrability as an active flow control are promising.

Performance analysis of double blade airfoil for hydrokinetic turbine applications

Hydrokinetic energy holds significant promise as a new, carbon-free energy source. The hydrokinetic turbine harnesses the power from moving water without the construction of a dam. Operational effectiveness of the wind and hydrokinetic turbines depend on the performance of the airfoils chosen. Traditionally, standard airfoils, like NACA and GOTINGEN, are used for wind and hydrokinetic turbines generating energy have the maximum lift coefficient about 1.3 at the stall angle of attack, about 12°. At these values, the flow velocities to produce electric energy are 7m/s and 3m/s for wind turbine and hydrokinetic turbine respectively. Using double blade airfoil, the fluid dynamics governing the flow field eliminates the separation bubble by the injection of the high momentum fluid through the gab of the double blade of airfoil by meaning of the flow control delays the stall up to an angle of attack of 20°, with a maximum lift coefficient of 2.06. Hence, using double blade airfoils in the wind and hydrokinetic turbines, minimum wind and hydrokinetic flow velocities to produce economical energies will be 3–4m/s for wind turbines and 1–1.5m/s or less for hydrokinetic turbines. Consequently, the wind power and hydrokinetic potentials of Turkey will be re-defined and increased accordingly.

3D solid fin model construction from 2D shapes using non-uniform rational B-spline surfaces

A computer aided design (CAD) tool has been specifically developed for rapid and easy design of solid models for surfboard and sailboard fins. This tool simplifies the lofting of advanced fin cross-sectional foils, in this instance based upon the family of standard airfoil series set by the National Advisory Committee for Aeronautics (NACA), whilst retaining a basic parametric description at each cross-section. This paper describes the way in which non-uniform rational B-spline (NURBS) surfaces are created from 2D profile splines, and are then used to generate 3D geometrical surfaces of the fins, which can be imported directly into commercial software packages for finite element stress analysis (FEA) and computational fluid dynamics (CFD). Pressure distributions, lift and drag forces are determined from a CFD flow analysis for various fins designed with this tool, and the results suggest that the incorporation of advanced foils into surfboard fins could indeed lead to increased performance over fins foiled using current standard techniques.

Low-drag airfoils for transonic flow of dense gases

Low-drag airfoils for transonic flow of BZT gases are constructed through a nonlinear small-disturbance theory on this topic. This kind of transonic flow is characterized by the high nonlinearity of the fluid thermodynamic behavior that is closely coupled with its compressible flow dynamics. Utilizing BZT gases may result in low drag exerted on airfoils operating at high transonic speeds. This advantage may be further improved by a proper design of the airfoils' shape. The modified airfoils are characterized by arcs along which the flow is sonic and that connect to a sharp tail. These airfoils may give the highest free stream Mach number for which the flow is nowhere supersonic. Using an analysis in the hodograph (velocity) plane, an analytical formula is derived to describe the sonic arc. Numerical computations using the Euler equations demonstrate that the modified airfoils have significantly lower pressure drag against standard airfoils and their critical Mach number is increased to higher values.

On the Design of Lifting Airfoils with High Critical Mach Number Using Full Potential Theory

We wish to construct airfoils that have the highest free-stream Mach number for a given set of geometric constraints for which the flow is nowhere supersonic. Nonlifting airfoils that maximize the critical Mach number \(\) for a given cross-sectional area are known to possess long sonic segments at their critical speed. To construct lifting airfoils, we proceed under the conjecture that an airfoil with a high value of \(\) has the longest possible arc length of sonic velocity over its upper and lower surface. In Kropinski et al. (1995) the lifting problem was tackled in transonic small-disturbance theory. In this paper we numerically construct lifting airfoils with high \(\) using the full potential theory and we show that these airfoils have significantly higher \(\) than some standard airfoils. We also construct airfoils with higher values of the lift coefficient, by relaxing the speed constraint on the lower surface of the airfoil to have a value less than sonic.

Robust linear and nonlinear strategies for solution of the transonic Euler equations

Full Newton nonlinear iteration using a Jacobian based on a high order discretization is compared with a widely used technique which uses a first order Jacobian. The linearized equations are solved using a level based block incomplete LU factorization with CGSTAB acceleration. Numerical tests are carried out using various standard airfoil shapes, at transonic and supersonic conditions. The full Newton, high order Jacobian technique is more robust and efficient than the usual approach. The Jacobian matrices can be readily solved using at least a level (2) block incomplete factorization preconditioner.

Hodograph design of lifting airfoils with high critical mach numbers

We wish to construct airfoils that have the highest free-stream Mach number M∞ for a given set of geometric constraints for which the flow is nowhere supersonic. Nonlifting airfoils which maximize M∞ for a given thickness ratio δ are known to possess long sonic segments at their critical speed. To construct lifting airfoils, we proceed under the conjecture that the optimal airfoil satisfying a given set of constraints is the one possessing the longest possible arc length of sonic velocity. A boundary-value problem is formulated in the hodograph plane using transonic small-disturbance theory whose solution determines an airfoil with long sonic arcs. For small lift coefficients, the hodograph domain covers two Riemann sheets and a finite-difference method is used to solve the boundary-value problem on this domain. A numerical integration of the solution around the boundary yields an airfoil shape, and three examples are discussed. The performance of these airfoils is compared with standard airfoils having the same lift coefficient and δ, and it is shown that the calculated airfoils have a 6%–10% increase in critical M∞.

On the construction and calculation of optimal nonlifting critical airfoils

Numerical calculations are carried out in the hodograph plane to construct optimal critical airfoil shapes and the flow about them. These optimal airfoil shapes give the highest free-stream Mach numberM ∞ for a given thickness ratio δ and tail angle θ t (nonlifting) for which the flow is nowhere supersonic. A relationship betweenM ∞ and δ for various θ t is given. Analytical and numerical solutions to the same problem are found on the basis of transonic small-disturbance theory. These results provide a limiting case asM ∞ →1, δ → 0 and agree well with the calculations of the full problem. Using a numerical method to calculate the flow about general (subsonic) airfoils, a comparison is made between the critical free-stream Mach numbers for some standard airfoil shapes and the optimal free stream Mach number of the corresponding δ and θ t . A significant increase in the critical free-stream Mach number is found for the optimal airfoils.

Quality control in exercise testing

An important factor in the optimization of the geometry of a horizontal-axis wind turbine (HAWT) is the design tip-speed ratio (DTSR). Previous research has suggested that DTSR values between 6 and 8 are desirable. However, a different approach was used in this study. Two standard airfoils with aerodynamic properties that are specified in the wind turbine airfoil catalog were selected and six different HAWT geometries were generated using the Schmitz formula for three DTSR values. These geometries were investigated theoretically based on the blade-element momentum (BEM) theory and numerically by using computational fluid dynamics (CFD) to calculate the rotor power efficiency and the optimal tip-speed ratio (OTSR). The six HAWTs had an average maximum power coefficient of 0.54 and an OTSR of 8.2 when the airfoil properties given in the airfoil catalog were used; these values were 0.43 and 6.7, respectively, when the airfoil properties were calculated using CFD and 0.41 and 7.3 when the HAWTs were simulated using three-dimensional CFD. To determine the power coefficient and OTSR values based on the BEM theory, the maximum value of CL/CD should be carefully selected considering factors such as the Reynolds numbers. Based on these findings, it was concluded that the CFD results validated the BEM theorem; the differences between the results obtained by these methods were likely due to the assumptions used when applying the BEM theory.