Reduced order modelling for aeroelastic aerofoil response to a gust

Abstract

Results for the gust response of the FFAST aerofoil calculated using computational fluid dynamics (CFD) and reduced order models (ROM) constructed using the eigenvalue realization algorithm (ERA) are presented. The CFD results are calculated using the Split Velocity Method (SVM). The SVM method rearranges the Euler equations retaining all terms after splitting the velocity into a prescribed gust and the remainder. SVM allows for the capture of the effects of the gust on the aerofoil and the aerofoil on the gust. In addition to the full SVM method a linearized version, used to generate the data for producing the ROM, is also presented. For larger gusts with over 5 ◦ changes in effective angle of attack it was found that the non-linearities due to large shock motions, which are not captured by the standard ROM, became important. So in addition a version of the ROM corrected with steady state information is presented, this gives more accurate results for longer gusts particularly when used in aeroelastic simulations.