Analysis of the Flow Characteristics of Several Non-Rotating Rotor Blades

Abstract

The investigation focuses on the analysis of the airfoil segment performanc es along rotor blades in the parked configuration . In this research wind tunnel experiments on two twisted blade geometries with different airfoils play ed a dominant role. These measurements were carried out by the Swedish Aeronautical Research Institute in the FOI LT1 low speed wind tunnel (in Stockholm, Sweden) and by the American National Renewable Energy Laboratories during the non -rotating configuration in the Unsteady Aerodynamic Experiment ( UAE) experiment in the NASA Ames wind tunnel (Langley, USA) . The span of the blade s were 2.375m and 5m, the STORK 5 WPX and the NREL Phase VI blade respectively . Five span locations (inboard, mid -span, outboard and tip region s) were considered and compared with the 2D airfoil characteristics. Wing model experiments with similar blade aspect ratio were included in the research. Furthermore the commercial CFD code FLUENT was used for the validation and analysis of the span wise lift and drag coefficients at 4 different pitch settings, 20deg., 30deg., 45deg and 60deg. respectively. The computed pressure distributions compared reasonably well, but the derived lift and drag showed quite some differences with the blade measurements. The lift coefficients for the sections beyond the leading edge stall angle of the STORK blade were larger then for the NREL blade and were close to that of the wing model with similar airfoil and aspect ratio. Lift and drag coefficients for the sections of the two blades were always much smaller then the 2D results. The drag values for both bl ade s showed quite some agreement and airfoil and blade dependency seemed to be small.