Concurrent aerodynamic-aeroelastic optimization

Concurrent Blade Aeromechanic and Aerodynamic Design Optimization  (adjoint approach) 

Why do we need to consider a concurrent design optimization? It is noted that some of existing aerodynamic design optimizations have been too focused on a single discipline area, tending to get diminishing returns. Also, one may often end up with such ‘over-designing’ as to exploit weakness of CFD rather than its strength.

A concurrent design and optimization framework has been developed with a demonstrable working method.  With the approach developed, both the blade ’steady’/mean aerodynamics (e.g. loss and efficiency) and aeroelastic (damping and/or dynamic response level) performance can be simultaneously evaluated. The nonlinear harmonic based  adjoint method enables the aerodynamic and aeroelastic sensitivities to be obtained very efficiently. The test case results have heighted the appeal of a concurrent D/O approach. 

The main method Ingredients:

1)      The nonlinear harmonic phase solution (He, 2008) enables steady (mean) and unsteady harmonic performances evaluated using 3 ‘steady-like’ solutions at 3 distinctive  temporal phases (-90°, 0° ,  90°). This basic formulation gives a unified framework for combined aerodynamic and aeroelastic design optimization.

2)      The unsteady harmonic adjoint formulation enables the sensitivities of steady (mean) and unsteady flow performances to be evaluated  by solving 3 ‘steady-like’ adjoint equations at the 3 phases - a natural extension of steady adjoint solver.  

 

References:

- L. He , "Harmonic Solution of Unsteady Flows around Blades with Separation”,  AIAA Journal, Vol.46. No.6. 2008.

- D.X. Wang and L. He. “Concurrent Aeromechanic and Aerodynamic Design Optimization Using the Adjoint Method”. in the proceedings of the 7th Asian CFD Conference, Bangalore, India, 26th - 30th Nov, 2007.

 - L. He and D. X. Wang, “Concurrent Blade Aerodynamic-Aeroelastic Design Optimization using Adjoint Method ASME Journal of Turbomachinery, Vol.133. No.1, 2011.