Adjoint-based shape sensitivity of multi-row turbomachinery

Abstract

The performance sensitivity of a low-pressure turbine stator-rotor stage of a commercial jet engine to its blades and hub shapes is analyzed. The derivatives of various metrics, such as isentropic efficiency, total pressure ratio, total pressure loss, and loss coefficient are computed using an adjoint solver capable of handling multi-row analyses. The importance of considering the coupled stator-rotor stage is highlighted from the computed sensitivities, which reveal that performing individual stator or rotor row component optimization may lead to an unexpected performance loss of the whole stage. The obtained coupled sensitivities are then used in an endwall contouring application, consisting of two Hicks-Henne bumps applied on the hub surface of the rotor to maximize stage efficiency, at locations selected where the impact is found to be the highest from the adjoint-based sensitivity analysis. The performance gain obtained with the bumps is correlated to the changes in the flow field, in particular with the effect on secondary flows.

Publication
Structural and Multidisciplinary Optimization