Low Reynolds Number Performance of a NACA 0015 and a GA(W)-1 aerofoil

[摘要] Due to the recent interest in a wide variety of low Reynolds number applications such as mini RPV's, wind tubrine fans, sailplanes etc., attention has been focused on the evaluation of efficient airfoil sections at chord Reynolds numbers from about 50,000 to about 1,000,00. In this experimental study, the low Reynolds number aerodynamic characteristics of two airfoil sections, namely the NASA GA(W)-1 and NACA-0015 were examined. These were compared to the ones obtained from previous investigations for the GU25-5(11)8 airfoil section. The airfoils were tested in the Reynolds number range from about 50,000 to about 500,000 and for incidences of 0 to 22. An automated pressure measuring system was developed to improve the speed and facilitate the measurements of pressures around the airfoil sections. The pressure measurements were converted to pressure coefficients and these were in turn integrated to provide normal force and pitching moment coefficients. Oil flow visualisation was used to obtain a better picture of the different flow phenomena around the airfoil sections. It proved to be an essential tool for obtaining information about the different flow fields which occur around the airfoil models when these were not apparent by pressure distributions. Many of the significant aerodynamic problems which occur in this low Reynolds number regime such as the creation and behaviour of laminar separation bubbles and the extreme sensitivity of the boundary layer to the test environment (i.e. free stream turbulence level, mechanical vibrations and noise levels) were highlighted. Significant differences were found in the behaviour of the boundary layer and subsequently in the aerodynamic characteristics of the three airfoil sections. This resulted in marginal differences as far as the Reynolds number operational range is concerned.

[发布机构] University:University of Glasgow

[关键词] Aerospace engineering, Mechanics, Fluid mechanics