A New Reduced Order Modeling for Stability and Forced Response Analysis of Aero-Coupled Blades Considering Various Mode Families

Abstract

This paper presents the description and application of a new method for stability and forced response analyses of aerodynamically coupled blades considering the interaction of various mode families. The method, here referred as multimode least square, considers the unsteady forces due to the blade motion at different modes shape families and calculates the aerodynamic matrixes by means of a least square (L2) approximations. This approach permits the prediction of mode families’ interaction with capabilities of structural, aerodynamic and force mistuning. A projection technique is implemented in order to reduce the computational domain. Application of the method on tuned and structural mistuned forced response and stability analyses is presented on a highly loaded transonic compressor blade. When considering structural mistuning the forced response amplitude magnification is highly affected by the change in aerodynamic damping due to mistuning. Analyses of structural mistuning without aerodynamic coupling might result in over-estimated or under-estimated response when the source of damping is mainly aerodynamic. The frequency split due to mistuning can cause that mode families’ interact due to reducing their frequencies separation. The advantage of the present method is that the effect of mode family interaction on aerodynamic damping and forced response is captured not being restricted to single mode families.

Adjoint-Based Aeroelastic Design Optimization Using a Harmonic Balance Method

“…However, the cost of performing a single time-accurate aero-elastic computation is still excessive, making adjoint optimization a very demanding task. In the attempt to circumvent this issue, reduced order models for aero-elastic turbomachinery computations have been proposed [3,4,5,6,7], the vast majority of them being based on the so-called energy method [8]. This method enables flutter and forced response analysis with engineering accuracy by means of unsteady fluid-dynamic simulations.…”

Aeroelastic Analysis of a Transonic Fan Blade with Low Hub-to-Tip Ratio including Mistuning Effects

“…A topic of particular interest to this investigation is the effect of random mistuning. The introduction of intentional mistuning has been proven to be an effective and practical way to alleviate flutter [18]- [20]. This paper has described the outcomes of the performed mistuned aeroelastic stability with a Monte Carlo simulation of random mistuning presented at the last.…”