Dynamic stall and three-dimensional effects. Final report for the EC DGXII Joule project JOU2-CT93-0345

摘要

This report describes the results of the project 'Dynamic stall and three- dimensional effects' which was carried out within the framework of the European Commission JOULE II programme. The objective of the current project has been to increase the understanding of the three-dimensional and unsteady aerodynamics of stall controlled HAWT's. The objectives have also been to develop 'engineering methods' - suitable for inclusion into aero-elastic codes - for dynamic stall and 3-D effects. The agreement between measurements and aeroelastic calculations often becomes unsatisfactory in the stalled region if 2-D steady aerofoil data are used. A major cause for this discrepancy seems to be due to the neglect, or unsatisfactory modeling, of dynamic stall and three- dimensional aerofoil characteristics for the rotating blade. Within the project: * 3-D (rotational) effects and dynamic stall have been studied by analysis of experiments and by the use of calculations. Calculations have been made with Navier-Stokes codes and viscid/inviscid interaction codes, * An unsteady 3-D vortex particle free wake method (GENVUP) has been extended with a scheme to model separation, * Five different 'engineering methods' for predicting dynamic stall are presented, * Two 3-D (rotational effects) 'engineering methods' are presented. The 'engineering methods' for dynamic stall have been applied to simulate the measured dynamic stall for 2-D tests as well as for measurements of C(sub n) on a blade section of a rotating blade. The methods seem to be sufficiently representative in order to calculate the main dynamic loads for a wind turbine during ordinary operation in stall, including mean loads and dependency upon turbulence intensity. However, the prediction of the limiting case, the stall induced vibration problem, has not been studied in the current project 58 refs, 46 figs, 2 tabs