The ECERTA Project

Topic

Computational aeroelasticity is often used to analyse behaviour that has already happened in flight. A greater challenge is presented by predicting behaviour before it happens, without guiding information. Since we are interested in exploiting high fidelity models, including CFD aerodynamic models, the computational cost of exploring a flight envelope defined by many parameters, is potentially prohibitive. Research is being carried out into two ways of defeating the problem of computational cost.

First, over several years Badcock and Woodgate have been developing eigensystem based approaches to analysing stability and doing model reduction of CFD based aeroelastic models. These approaches have been found to be one to two orders of magitude faster than traditional time domain approaches to calculating stability. Under the ECERTA project these methods have been extended to allow robust parallel large scale eigenvalue calculations for multiple modes. The resulting method is called the Schur complement method, and involves linear frequency domain forced calculations to build a response matrix, and the solution of a nonlinear eigenvalue problem to track aeroelastic modes. This method has been applied to calculate the influence of structural variability on stability through Monte-Carlo, perturbation and interval analysis.

Finally, work is ongoing to use the system critical eigenvector to develop a nonlinear reduced order model which can predict limit cycle oscillations.

Background Papers

1. Woodgate, M.A, Badcock, K.J., Rampurawala, A.M., Richards, B.E., Nardini, D and Henshaw, M.J., Aeroelastic Calculations for the Hawk Aircraft Using the Euler Equations, J Aircraft, 40(4), 2005, 1005-1012.
2. Woodgate, M.A. and Badcock, K.J., On the fast prediction of Transonic Aeroelastic Stability and Limit Cycles, AIAA Journal, 45(6), 2007, 1370-1381.
3. Badcock, K.J., M.A. Woodgate, M.A. and Richards, B.E., The Application of Sparse Matrix Techniques for the CFD based Aeroelastic Bifurcation Analysis of a Symmetric Aerofoil, AIAA Journal, 42(5), 883-892, May, 2004.
4. Badcock, K.J., Woodgate, M.A. and Richards, B.E., Direct Aeroelastic Bifurcation Analysis of a Symmetric Wing Based on the Euler Equations, Journal of Aircraft, 42(3),731-737, 2005.

Progress

• Schur complement method developed and tested on range of aeroelastic problems - SDM paper 2008
• LCO prediction based on a projection based ROM demonstrated for a model wing - Loen paper
• Transonic Flutter Predictions for a Generic Fighter Configuration - FSI Presentation paper
• CFD Based Aeroelastic Stability Predictions Under the Influence of Structural Variability - SDM Paper 2009
• LCO prediction via model reduction - D2.4
• On How Structural Model Variability Influences Transonic Aeroelastic Stability - SDM paper 2010

Contacts