Aerodynamic Charcterization of Airfoils at Low Reynolds Number Flow and under Varying Turbulence Intensities in Flow

Abstract

Research in low Reynolds number aerodynamics has increased significantly due to its newlinelarge number of applications. But unmanned aerial vehicles suffer from poor performance newlinedue to lack of understanding of flow physics in the low Reynolds number flow regime. newlineNumerical and experimental studies of low Reynolds number flows pose several challenges. newlineIn the present study, numerical computations of low Reynolds number flow have been newlinecarried out for symmetric airfoil NACA 0018 and high performance airfoil Eppler 387 using newlineAnsys Fluent code and over Eppler 387, SD7073, MH45 and S1223 airfoils using XFLR newlinecode. Computations using XFLR code have been performed for four airfoils for Reynolds newlinenumber of 0.6x105 newline, 1.0x105 newlineand 2.0x105 newline newlinefor three values of free stream turbulence intensity newlinein the flow. Flow computations over NACA 0018 airfoil have been performed for three newlineReynolds number (0.8x105 newline, 1.2x105 newlineand 1.6x105 newline newline) using four turbulence models, namely, k-and#969; newlineSST model, low Reynolds number k-and#969; SST model, and#947;-Reand#952;t transition model and k-kL-and#969; newlinetransition model. For Eppler 387 airfoil, numerical simulations have been carried out for newlineReynolds number of 0.6x105 newline newlineand 1.0x105 newline newlineusing Ansys Fluent and for two transition models newlinenamely, and#947;-Reand#952;t transition model and k-kL-and#969; transition model. In addition, computations have newlinebeen carried out for Eppler 387 by varying the free stream turbulence intensity in the flow. newlineThe studies have been carried out to assess the performance of airfoils for Reynolds number newlinevarying from 0.6x105 newline newlineto 2.0.x105 where the aerodynamic characteristics are known to change newlinesignificantly. Finally, measurements of velocity and turbulence intensity was carried over newlineEppler 387 airfoil at five stations along the chord at Re= 0.6x105 newline newlineand 1.0x105 newline newlineand angle of newline newlineattack, and#945; is varied from 0o newlineto 10o newline. The measurement was carried out at MART Wind Tunnel newline newlineFacility at NAL Bangalore. newline