Application of a three-dimensional viscous transonic inverse method to NASA rotor 67

The development and application of a three-dimensional inverse methodology in which the
blade geometry is computed on the basis of the specification of static pressure loading distribution is
presented. The methodology is based on the intensive use of computational fluid dynamics (CFD) to account
for three-dimensional subsonic and transonic viscous flows. In the design computation, the necessary blade
changes are determined directly by the discrepancies between the target and initial values, and the calculation
converges to give the final blade geometry and the corresponding steady state  flow solution. The application
of the method is explored using a transonic test case, NASA rotor 67. Based on observations, it is conclusive
that the shock formation and its intensity in such a high-speed turbomachinery flow are well defined on the
loading distributions. Pressure loading is therefore as effective a design parameter as conventional inverse
design quantities such as static pressure. Hence, from an understanding of the dynamics of the flow in the fan
in relation to its pressure loading distributions, simple guidelines can be developed for the inverse method in
order to weaken the shock formation. A qualitative improvement in performance is achieved in the
redesigned fan. The final flow field result is confirmed by a well-established commercial CFD package.

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