Simulation of Pitching Moment and Drag by a State-Space Dynamic Stall Model - Experimental Correlation

The Peters-Modarres semi-empirical dynamic stall model is extended to the simulation of pitching moment and drag. The new model is correlated with experimental data. In particular, wind tunnel and water tunnel tests of harmonically pitching Boeing VR-12 and VR-7 airfoils are used for validation, including Mach numbers of 0.2, 0.3, and 0.4, and reduced frequencies of 0.02 - 0.25. Secondary peaks in the pitching moment stall data are modeled with an additional secondary stall model: a simple second-order equation driven by a rectangular pulse, requiring no additional states in simulation. As a state-space model, the extended model is in a form useful for design of controls and flutter analyses. An optimization routine is used to determine the empirical parameters of the stall model by comparison of the computed results with each experimental case, producing a set of 12 stall parameters and 2 static corrections. The results show good agreement for each case, and are an improvement over previous efforts by Ahaus to correlate pitching moment and drag data.