Airfoil Analysis Research Articles

Parameter-Based Design and Analysis of Wind Turbine Airfoils with Conformal Slot Co-Flow Jet

A co-flow jet (CFJ), an active flow control method combining blowing and suction control, can effectively suppress the stall of airfoils. However, the streamwise jet channel along the upper surface of a conventional CFJ airfoil reduces the thickness and camber of the baseline, degrading the aerodynamic performance when the jet is inactive. The conformal slot CFJ airfoil was proposed to address this problem, but the design method is still absent. This paper proposed a general design method based on parameters including the slot angle, transition shape and distance of the injection and suction slot. The mechanism of the best parameter was analyzed. The designed conformal slot CFJ airfoil was checked under different jet intensities, and the turbine power curve was predicted when substituting CFJ airfoils for the baseline. Compared with the conventional CFJ airfoil, the designed conformal slot CFJ airfoil has three advantages: eliminating the performance loss when the jet is off, saving jet energy when suppressing the flow separation, and improving the power generation of wind turbines at low wind speeds.

Nonlinear FE aeroelastic analysis of membrane airfoils with fixed and elastic supports

This paper presents a nonlinear aeroelastic analysis of membrane airfoils using the finite element method. The model uses the aerodynamic potential flow models based on the Prandtl–Glauert and Theodorsen’s thin-airfoil theories. The structural model accounts for the nonlinear strain due to the membrane deformation. The final aeroelastic system is presented in the time-domain which enables both static and transient response analysis. A comparison between the linear and the nonlinear aeroelastic results is presented. The effect of the elastic supports and their stiffness ratio on the aeroelastic characteristics is also investigated for static and dynamic responses due to step or harmonic wind loadings with a comparison to the fixed-ends membranes.

Numerical analysis of co flow jet airfoil on enhancement of aerodynamic performance

Numerical analysis of co flow jet airfoil on enhancement of aerodynamic performance

Modelling and Validation of a Remotely Operated Towed Vehicle and computational cost analysis of Umbilical Cable

This paper deals with modelling of a remotely operated towed vehicle (ROTV) and attached umbilical cable, as a means of exploration and research in the ocean. Fossen's approach is used for modelling the ROTV using XFLR5 for airfoil analysis. The lumped mass-spring approach with fourth-order Runge-Kutta solver is used as umbilical cable model. It is shown that the mean square error exponentially increases when the segment length exceeds 4 meters, and the computation time is linearly increasing with the number of nodes. The results show that the umbilical cable model combined with the ROTV model can reproduce the output of the real data when taking modelling uncertainties into consideration.

XFOIL Performance Validation for Medium-Scale Variable Pitch UAV Rotor Systems

This study focuses on experimentally validating the performance of XFOIL, a sophisticated software airfoil analysis tool used for approximating lift and drag coefficients. XFOIL output data was incorporated into a theoretical model simulating a variable pitch rotor system operating in a hovering state. The output of the Blade Element Momentum Theory (BEMT) rotor model is compared to thrust and power output performance data collected from a constructed rotor test bench and analysed in MATLAB. Using XFOIL as input, the BEMT rotor model was observed to yield good robust results when compared to experimental data, but demonstrated sensitivity to airfoil performance characteristics, laying the groundwork for future empirical validation. In comparing BEMT model performance, it was interesting to find that thrust performance remained within tolerance in contrast to an overprediction of rotor power output resulting from XFOIL drag at high blade pitch angles. Upon further interrogation by means of variable isolation, XFOIL demonstrated instability resulting from sensitivity to variability of model constraints. Modification of rotor geometry definitions or environmental constants beyond the test environment framework showed simulated systems may not necessarily behave reliably nor enhance output performance. This highlights the critical importance and utility of experimentation for understanding theoretical model behaviour or validating simulation output performance.

Stochastic aeroservoelastic analysis of a flapped airfoil

In order to increase the operability range of wings in terms of speed, the suppression of aeroelastic vibrations due to flutter phenomena using a trailing edge flap is analyzed. The aeroelastic modelling of a three degrees of freedom 3DOF airfoil in unsteady incompressible flow with pitch and control surface stiffness non-linearities is studied and an augmented state space representation is used for the time domain analysis of the problem. A V-stack piezoelectric actuator is used to move the trailing edge flap and its dynamic behavior is included in the analyses by means of a finite element model; the actuator input voltage saturation is also taken into account. A heuristic method, named Population Decline Swarm Optimization, is used for the tuning of the filtered PID controller parameters for different velocity values. The optimization algorithm is also used for the tuning of the Simple Adaptive Controller SAC invariant gains. A general uncertain state space modelling of the aero-servo-elastic plant is provided and used first for the open loop stochastic flutter analysis. Then, the stochastic robustness analysis is carried out to verify the robustness to structural, aerodynamic, and actuator parameters uncertainties of the proposed flutter suppression systems and to compare the gain scheduled PID approach with the SAC scheme.

Parametric research and aerodynamic performance analysis of wind turbine airfoil with added flap

A self-popped up flap is added to the airfoil (S809) suction surface to improve aerodynamic performance under large angle of attack (AOA) inspired by the slightly popped up feathers on the trailing edge of a bird’s wing. The response surface methodology (RSM) optimization of H, D, and θ is conducted. The lift–drag ratio of an airfoil is taken as the optimization response target, and the Box–Behnken design is adopted to design the experiment scheme for H, D, and θ. Multivariate quadratic polynomials are used to carry out equation regression analysis on the combined results of 17 sample schemes, and the mathematical surrogate model between the flap structure parameters and the airfoil lift–drag ratio and the optimal design parameter combination of the flap structure are obtained. The clean airfoil and the airfoil with optimal flap are compared and analyzed from the static and dynamic aerodynamic characteristics by numerical simulation. The calculation results show that the optimal flap obtained by RSM increases the pressure difference between the suction and the pressure surfaces at large AOA, suppresses flow separation on the suction surface, and delays the stall AOA. The airfoil with optimal flap leads to a smaller separation vortex and wake vortex, therefore delaying the dynamic stall effect.

Aerodynamic and bending analysis of low-speed airfoils at high reynold number

The growing demand for UAVs with short take-off landing, high payload capabilities, and better aerodynamic efficiencies has emerged studies to find an airfoil that can satisfy the current market needs. In this research, a computational analysis was carried to find out the most suitable airfoil design at a low Reynolds number based on aerodynamic as well as mechanical properties. In this research, an Aerodynamic and Mechanical comparison has been done among airfoils CH 10, EPPLER 420, EPPLER 421, EPPLER 423, GOE 448, FX 62-K-153, FX 63–137, S1210 (12 %), S1223, S1223 RTL, NREL’S S825, FX 74-CL5-140, FX 74-CL5-140 MOD based on computational simulation to find out most suitable airfoil for low-speed Fixed-Wing UAV. This research is carried out at Reynolds number 300,000 on a test specimen wing with a Wing-span of 200 cm and a Wing-chord of 30 cm using XFLR-5 (version 6.54), ANSYS-Fluent (Version 2021 R2), and SOLIDWORKS Simulation (Version 2022 R1). Aerodynamic comparison concluded S1223 as the most dominating airfoil based on Lift Force and CH 10 as the most dominating airfoil based on Lift-to-Drag ratio. On the other hand, wing bending analysis concluded EPPLER 420 as the most dominating airfoil with the least wing bending which is followed by CH 10 airfoil. This research concluded CH 10 as the most suitable airfoil for low-speed Fixed-Wing UAVs based on its balanced contribution aerodynamically and mechanically that will help Fixed-Wing UAVs to carry a heavy load at low speed as well as decrease manufacturing costs by reducing extra support structure that will be required for other airfoils.

Parameter analysis of a multi-element airfoil for application to airborne wind energy

Abstract. Multi-element airfoils can be used to create high lift and have previously been investigated for various applications such as in commercial aeroplanes during take-off and landing and in the rear end of Formula One cars. Due to the high lift, they are also expected to have high potential for application to airborne wind energy (AWE), as confirmed by recent studies. The goal of this work is to investigate a multi-element airfoil for application to AWE via a parametric study in order to further the understanding and improve the knowledge base of this high-potential research area. This is done by applying the computational fluid dynamics code OpenFOAM to a multi-element airfoil from the literature (the “baseline”), set up for steady-state 2D simulations with a finite-volume mesh generated with snappyHexMesh. Following a grid dependency study and a feasibility study using simulation data from the literature, the angle of attack with the best performance in terms of E2CL (E is the glide ratio; CL is the lift coefficient) is identified. The maximum E2CL is found to be approximately 7 times larger than that of a typical single-element AWE airfoil, at an angle of attack of 17∘. Having found the ideal angle of attack, a parametric study is carried out by altering the relative sizes and angles of the separate airfoil elements, first successively and then using promising combinations. The limits of these changes are set by the structural and manufacturing limitations given by the designers. The results show that E2CL can be increased by up to 46.6 % compared to the baseline design. Despite the increased structural and manufacturing challenges, multi-element airfoils are therefore promising for AWE system applications, although further studies on 3D effects and drone–tether interactions, as well as wind tunnel measurements for improved confidence in the results, are needed.

A method of sequential log-convex programming for engineering design

A method of Sequential Log-Convex Programming (SLCP) is constructed that exploits the log-convex structure present in many engineering design problems. The mathematical structure of Geometric Programming (GP) is combined with the ability of Sequential Quadratic Program (SQP) to accommodate a wide range of objective and constraint functions, resulting in a practical algorithm that can be adopted with little to no modification of existing design practices. Three test problems are considered to demonstrate the SLCP algorithm, comparing it with SQP and the modified Logspace Sequential Quadratic Programming (LSQP). In these cases, SLCP shows up to a 77% reduction in number of iterations compared to SQP, and an 11% reduction compared to LSQP. The airfoil analysis code XFOIL is integrated into one of the case studies to show how SLCP can be used to evolve the fidelity of design problems that have initially been modeled as GP compatible. Finally, a methodology for design based on GP and SLCP is briefly discussed.

Efficiency of Pulsating Base Bleeding to Control Trailing Edge Flow Configurations

As high-pressure-turbines operate at extreme temperature conditions, base bleed can be applied at the trailing edge of the airfoils, enhancing the thermal protection along the trailing edge surface, but also disrupting the trailing edge flow and altering the overall aerodynamic pressure losses. The current work explores the potential use of base bleed as a flow control tool to modulate the flow between turbine blade rows. Through the numerical analysis of a symmetric airfoil immersed in a subsonic flow, the effects that trailing edge ejection has on the base region properties and the downstream flow are evaluated. In particular, previous research constrained to steady blowing is now extended to consider an unsteady pulsating base bleed injection. Three injection frequencies are investigated, covering a wide range of base bleed intensities. The results presented herein demonstrate that pulsating bleed flow is more efficient than its steady counterpart in terms of reducing pressure losses and controlling the primary frequency of the downstream oscillations for the same mass flow injection.

Optimization of the Underground Bidirectional BRT Ventilation Systems

The urban traffic is a common concern in the large cities around the world, and th calls for high technology to improve its efficiency and reduce its costs. The underground traffic development is one solution used often in the metropolitan cities like Paris and London. In China, the ventilation system of the underground bidirectional BRT still needs more refinement to achieve the sustainable development, though the underground traffic system has developed very fast. The airfoil structure is adopted abroad to dilute the polluted air in the subway stations and increase the ventilation efficiency, yet it has not been applied in China. This paper studies the reduction of the piston wind loss by airfoil structure on the basis of piston principle, so as to improve the role of the piston wind in the ventilation process. In the mathematical simulation, it is also proved that this method can substantially increase wind energy by 63.27% per meter of the underground road, improving the ventilation efficiency of the underground BRT. Due to the failure to refine the parameter curve of the airfoil structure, the simulation data has some deviations. In future studies, in order to make up for the shortcomings of this study, it is necessary to use XFLR software to carry out refined parameter analysis of laminar airfoil.

Aerodynamic Design Consideration for Stability of a Lightweight Solar-Powered Aircraft

Aerodynamic design analysis was conducted for the stability of a lightweight solar aircraft weighing 3 kg and a wingspan of 3.2 m. Airfoil analysis was conducted on four selected airfoils. The following factors were considered: good aerodynamic characteristics, low Reynolds number, high lift, low drag, high lift-to-drag ratio, quiet moment coefficient, moderate thickness, and camber curvature. WE-3.55.93 airfoil was selected as best and used to design the wing, and NACA 0008 was used to develop the empennage. The fuselage was designed with two compartments 1.9 m long, and the second compartment is made of aluminium or carbon fibre to reduce weight. The first compartment was 0.95 m long and 0.4 m in diameter. The centre of gravity was determined for the importance of the various aircraft components to ensure aerodynamic stability and balance. The complete assembly was designed using XFLR5 v6 software.

CFD analysis of the low Reynolds S1223 airfoil

The Low Reynolds S1223 airfoil has been modeled and performance has been evaluated numerically through CFD open source OpenFOAM suite. The numerical results have been validated with available experimental data at Re = 2e05 obtained by means of wind-tunnel tests. Results are also reported at Re = 2e04 and Re = 2.06 in terms of lift and coefficients, streamlines, pressure coefficient and velocity distributions, at 3 different AOA. The main original aspect of this numerical research has been the sensitivity analysis of the aerodynamic performance of the S1223 airfoil over a wide range of Reynolds number. In particular, the effects at low Reynolds number 2e04 have been investigated.

Analytical Study of Double Wedge Airfoil for Supersonic Applications and Shape Modification for Subsonic Applications

A Double Wedge airfoil is an airfoil for supersonic blades and wings, with a wedge like tapered sharp leading and trailing edges. The shock waves and the expansion waves govern the supersonic characteristics of the double wedge airfoil. The present work is based on the design and aerodynamic analysis of double wedge airfoil at supersonic regime and shape modification of the airfoil for subsonic regime. The flow analysis is carried out using ANSYS Fluent, which is CFD based software. The supersonic analysis is performed for Mach number of 2.0. The airfoil was modified for subsonic applications and the analysis was performed for Mach number 0.7. Blowing technique was incorporated to further improve the aerodynamic performance of the modified double wedge airfoil. From the simulated results, it was found that the co-efficient of drag of double wedge airfoil at Mach number of 2.0 agreed with the manual calculations. The modified airfoil gave optimum performance with the addition of a blowing stream at subsonic speeds.

Computational Fluid Dynamic (CFD) Analysis of NACA Airfoil for Wind Turbine Blade Design

The paper presents a conceptual study of performance enhancing devices of an airfoil using computational Fluid Dynamics (CFD) technique. Two simple passive devices were selected and examined for increase in lift and decrease in drag. The target of the study was to evaluate and select the best airfoil suitable for wind turbine blade in a typical Nigeria Environment. The selected airfoils includes; NACA 0012, NACA 2412 and NACA 4412 while the selected angle of attack are; 0°, 4°, 8° and 12. The various airfoils geometry was created using Autodesk inventor and imported into ANSYS design modeler while meshing of the airfoil fluid geometry was done with the aid of ANSYS Meshing. To implement the ANSYS design modeller, the spalart-Allmaras turbulence model was selected and strain/vorticity based sub-option subsequently selected. The CAD Model was prepared in CATIA VS R19 while Pre-processing and simulation was done in ANSYS ICEM CFD 16.0 and ANSYS FLUENT 16.0 respectively. Result of the study shows that NACA 4412 at 4° angle of attack gave the maximum lift to drag ratio and hence, was considered for use in the design of wind turbine blade. The results justify the optimum position for enhancing airfoil performance at a specified angle of attack Keywords : Airfoil, Wind turbine blade, Angle of attack, Coefficient of lift, Coefficient of drag and CFD analysis DOI: 10.7176/IEL/12-2-03 Publication date: May 31 st 2022

Study and Comparison Analysis of Conventional Light Weight UAV Airfoils using XFLR Analysis

In Aeronautical industries one of the very important issues in smart UAV is the duration of flight since the overall time uses standard power that may be an unusable product, includes a restricted life, and is cost. But, there's an enormous demand for exploitation, a limitless non-exhaustible supply of power. So an alternative source of power calculation is required to get efficient flying conditions for a UAV. This work is to study and analysis of solar energy UAV airfoil using XFLR analysis. A UAV with 2.98Kg of weight is studied for power calculation, implementation of solar cells, and design aspects, including airfoil, fuselage, and tail section. From analysis it is found that UAV flight performance at solar radiation intensities above 451.23 W/m2 for power system which worked to increase the battery life and works more efficiently at solar radiation intensities above 666.5 W/m2.

Aerodynamic performance analysis of a supercritical airfoil in the helicopter main rotor

Helicopters can be considered as any-terrain vehicles, as they can take off and land at any location. The aerodynamic characteristics of helicopters are more complicated than those of fixed-wing aircraft. The rotor is the source of lift and thrust for helicopters. The complex aerodynamic characteristics of helicopters are due to their rotational frame and variations in the velocity and pressure throughout the blades. Moreover, the airfoil undergoes phase changes because half of the phase exhibits a trailing edge toward the flow. In this study, four isolated helicopter rotor blades were analyzed using ANSYS Fluent in terms of flow in a static domain under non-rotating conditions. Supercritical airfoils used in high-speed aircraft have been found to be incredibly useful in the transonic region. They increased the critical and drag divergence Mach numbers. Incorporating supercritical airfoils in helicopter rotor blades ensures suitable flow characteristics and more than 50% efficiency compared to those of the HH02 blade in a stationary frame. Analyses were conducted for HH02 and NASA SC(2)-0714 airfoils with Mach numbers of 0.3, 0.4, and 0.5 without rotation. The post-processing results prove that the NASA SC(2)-0714 airfoil rotor achieves a better aerodynamic performance than the HH02 airfoil rotor.

Comparative Numerical Aerodynamics Performance Analysis of NACA0015 and NACA4415 Airfoils

The climate crisis caused by global greenhouse gas emissions has led to many disasters around the world in recent years. Some of these disasters are floods in various parts of Europe, melting of Arctic glaciers, and rising water levels in the oceans. People living on islands in Southeast Asian countries are forced to migrate due to rising water levels. With the increase in the frequency of such situations, life on earth is at risk. Greenhouse gas emissions harm not only humans but also animals and plants. The most effective measure that can be taken against this is to stay away from fossil fuels. With the use of fossil fuels, the carbon ratio in the atmosphere increases, and climatic imbalances occur. For this reason, the interest in alternative energy sources is increasing. Wind energy is one of the most widely used renewable energy sources. This is due to the low cost of installation and ease of use. The most important factor affecting the aerodynamic efficiency of wind turbines is the blade profiles. Numerous types of wing profiles have been designed and put into use. In this study, numerical analyzes of NACA 0015 and NACA 4415 airfoils at various angles of attack were performed by determining forces every five degrees between 0 and 20 degrees using ANSYS Fluent commercial software. Lift coefficients and drag coefficients were also calculated for the angles of attack used. According to the analysis results obtained, optimum attack angles were found for each airfoil. As a result, NACA0015 and NACA4415 airfoils were compared in terms of their performance.

Nonlinear aeroelastic analysis of a multi-element airfoil with free play using continuation method

In this study, the nonlinear aeroelastic response of a NACA0012 airfoil with leading-edge and trailing-edge control surfaces is studied numerically using a modified filtered impulse function method and continuation method. The source of nonlinearity comes from the free play behavior of both control surfaces which leads to the nonlinear properties of the structural stiffness matrix. The aerodynamic responses of these aeroelastic systems for varying oscillation frequencies are assumed to be linear for small deflections. These responses are developed using a reduced-order model by using the proposed modified filtered impulse function method on inviscid rotational flows computed using CFD methods for the Euler Equations. Key factors for maintaining accuracy using the proposed filtered impulse function are discussed with examples. The linearized aeroelastic equations are solved using the continuation method with the adaptive step size for three different situations that could arise in practice. The analysis process is conducted in the modes tracking and parameter variation separately. This study shows that compared to the airfoil with a single trailing-edge control surface in free play, the presence of the leading-edge flap motion could decrease the flutter speed and dominate the flutter mode in the absence of free play behavior. However, only slight differences could be observed from the limit cycle oscillations (LCO) analysis for which the structural nonlinearity is dominant owing to free play.