MULTI-OBJECTIVE OPTIMIZATION OF TURBOMACHINERY CASCADES
FOR MINIMUM LOSS, MAXIMUM LOADING, AND MAXIMUM GAP-TO-CHORD RATIO
AIAA Multidisciplinary Analysis and Optimization Conference
and Exhibit,
Long Beach, CA, Sept. 5-8, 2000.
This paper illustrates an automatic multi-objective design optimization
of a two-dimensional airfoil cascade row having a finite number of airfoils.
The objectives were to simultaneously minimize the total pressure loss,
maximize total aerodynamic loading (force tangent to the cascade), and
minimize the number of airfoils in the finite cascade row. The constraints
were: fixed mass flow rate, fixed axial chord, fixed inlet and exit flow
angles, fixed blade cross-section area, minimum allowable thickness distribution,
minimum allowable lift force, and a minimum allowable trailing edge radius.
This means that the entire airfoil cascade shape was optimized including
its stagger angle, thickness, curvature, and solidity. The analysis of
the performance of intermediate airfoil cascade shapes were performed
using an unstructured grid based compressible Navier-Stokes flow-field
analysis code with k-e turbulence model. A robust stochastic algorithm
was used in the automatic multi-objective constrained shape design process
that had 18 design variables, 5 nonlinear constraints, and 3 objectives.
Simultaneous reductions of the total pressure loss, increases of the total
loading, and decreases of the number of airfoils were achieved using this
method on a VKI high subsonic exit flow axial turbine cascade.
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