XFOIL vs CFD performance predictions for high lift low Reynolds number airfoils (original) (raw)
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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...
CFD Modelling of Laminar-turbulent Transition for Airfoils and Rotors Using the g -R e q Model
When predicting the flow over airfoils and rotors, the laminar-turbulent transition process can be important for the aerodynamic performance. Today, the most widespread approach is to use fully turbulent computations, where the transitional process is ignored and the entire boundary layer on the wings or airfoils is handled by the turbulence model. The correlation based transition model has lately shown promising results, and the present paper describes the effort of deriving the two non-public empirical correlations of the model to make the model complete. To verify the model it is applied to flow over a flat plate, flow over the S809 and the NACA63-415 airfoils, flow over a prolate spheroid at zero and thirty degrees angle of attack, and finally to the NREL Phase VI wind turbine rotor for the zero yaw upwind cases from the NREL/NASA Ames wind tunnel test. Nomenclature dU/ds Acceleration along a streamline k Turbulent kinetic energy K Flow acceleration parameter (u/U 2 )dU/ds Re x Reynolds number based on length, rxU ref /m Re q Momentum thickness Reynolds number, rqU 0 /m Re qc Critical momentum thickness Reynolds number Re qt Transition onset momentum thickness Reynolds number, rq t U 0 /m R e qt Local transition onset momentum thickness Reynolds number, obtained from transport equation R T Viscosity ratio rk/(mw) Re u Vorticity (strain rate)Reynolds number ry 2 S/m S Absolute value of the strain rate, 2 1 2 k U ( ) Airfoil Computation, NACA 63-415
Aerodynamic Performance Prediction of Wind Turbine Airfoil Through CFD
2016
Department of Mathematics, NEDUET, Karachi, Pakistan Institute of Space Technology (IST), Karachi, Pakistan Corresponding Author: tabindakanwal1@gmail.com ABSTRACT: Energy is considered as most vital instrument of socioeconomic development of a country. Unfortunately in our country enhancement in energy production is not as increased as its demand. Currently country is facing serious energy crises. This issue has not been addressed properly as well as could not find available economical and long term solutions. Wind turbines are one of the vital sources of energy and very much in progress worldwide. Research and development of airfoils for wind turbine have been largely focused by researchers for last three decades. In present study numerical computations is carried out for S809 airfoil which is specifically designed for horizontal axis wind turbine (HAWT). Aerodynamic performance data for S809 airfoil is generated through CFD and compared with available experimental data. Gridgen i...
Journal of Engineering Advancements, 2022
This paper presents an evaluation of five different turbulence models by comparing the numerical data derived from these models using ANSYS Fluent with experimental data at a Reynolds number and a Mach number of 0.05 × 106 and 0.015 respectively based on the centerline chord of the airfoil for the flow over NACA 0012 and NACA 2412 airfoils. Moreover, the aim of the present study is to demonstrate the difference in aerodynamic characteristics of the airfoils in order to find aerodynamically more advantageous airfoil. It is concluded that Spalart-Allmaras model and k-ω SST model are capable of providing the most accurate prediction for lift coefficient at a low angle of attack for both airfoils. Standard k - ε model gives a slightly low value of lift coefficient at low angle of attack and slightly high value of lift coefficient at high angle of attack for both airfoils. k-ω SST model, Spalart-Allmaras model, Transition k-kL - ω model, and γ-Rⅇθ Transition SST model can predict drag co...
Computational Analysis of the 2415-3S Airfoil Aerodynamic Performance
This paper deals with the numerical simulation of the twodimensional, incompressible, steady air flow past an airfoil for a solar powered unmanned aerial vehicle (UAV) with internal propulsion system. This airfoil results from a NACA 2415 four digits family base airfoil modification [7] and has a propulsive outlet with the shape of a step on the suction surface. The analysis involved the airfoil's aerodynamic performance which meant obtaining lift, drag and pitching moment coefficient curves as a function of the angle of attack (AOA) for the condition where the engine of the UAV is turned off called the gliding condition and also for the blowing propulsive condition by means computational fluid dynamics. The computational domain has been discretised using a structured mesh of 188 x 200 tetrahedral elements. The RNG k-ε model is utilized to describe the turbulent flow process as it was followed in . The simulations were held at a Reynolds number of 300000. Results allowed obtaining lift and drag forces and pitching moment coefficient and also the location of the separation and reattachment points in some cases by means of the wall shear stress on the suction surface as well as velocity contours and streamlines for both conditions at different angles of attack, from 0 to 16 degrees with the smallest increment of 4 degrees. Finally, results from both cases were compared and the influence of the propulsive flow on the aerodynamic characteristics of the airfoil has been analysed turning out that it improves significantly the performance of the airfoil reaching values up to 1,8 times in terms of lift at high angles of attack.
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...
A Comparative Study of Turbulence Models on Aerodynamics Characteristics of a NACA0012 Airfoil
International Journal of Integrated Engineering, 2018
This paper presented a computational fluid dynamics (CFD) simulation of air flow past a 2D model NACA0012 airfoil at high Reynolds number (Re = 3.0 x 10 6) at various angles of attack (-10 to 15). The simulations were undertaken to inform on how the fluid flowed around the airfoil by solving the steady state governing equations of continuity and momentum conservation that are combined with one of three turbulence models Spalart-Allmaras, Realizable k-ε and k-ω shear stress transport (SST). It is observed that the Realizable k-ε eliminates the small separation bubble on the upper surface of the airfoil and delaying separation flow. Also, for the lift coefficient, CL and drag coefficient, CD investigated in this paper, the predicted data have good agreement with other published data.
METAL: Jurnal Sistem Mekanik dan Termal
Unlike in the case of a high Reynolds number airfoil, selecting a turbulent closure model for a low Reynolds number airfoil is still a challenge. A turbulent model used for high Reynolds number airfoil is not necessarily suitable for low Reynolds number airfoil due to the presence of separation bubbles in the low Reynolds number airfoil. In this study, we used two simple turbulent models, Spalart-Allmaras and k-ω , in calculating the thrust coefficient of low Reynolds number airfoil used as a propeller to determine their accuracy. It was found that there was a significant discrepancy between the numerical calculation results by both the turbulent model and the experimental data. The k-ω was a little more accurate than Spalart-Allmaras turbulent closure model.
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.