Session: 04-18 Combustion Modeling VI

Paper Number: 126700

126700 - Verification of an Adjoint Code for FGM Combustion 

The adjoint method efficiently computes the sensitivity of a global output, such as the average outlet temperature or NOx of a combustor, with respect to a large number of input variables, such as the centroids of the wall boundary faces. This sensitivity, or gradient, can be used in an optimization algorithm, in particular for shape design to minimize a cost function.

The discrete adjoint requires differentiating the code, typically using Automatic Differentiation. The adjoint solution process must be executed in the reverse order as the flow, or primal, solution. In this work, the adjoint model in Simcenter STAR-CCM+ ® is extended to the Flamleet Generated Manifold (FGM) combustion model. Since the code is complex with a large number of interacting models, a careful verification is required to ensure that the important parts of the code are differentiated properly, and the order of code execution is correct.

To verify the adjoint, the automatic differentiation is solved in the forward, or tangent, mode, for a simple flame, and compared with finite difference results. The same problem is then solved in adjoint, or reverse, mode and again compared with the tangent and finite-difference results, and the error assessed.

The verified code is then applied to a simple gas-turbine combustor optimization of mesh deformation to minimize outlet temperature variation.

Presenting Author: Stefano Duranti Siemens Digital Industries

Presenting Author Biography: Stefano is a senior software developer and has been at Siemens CD-Adapco for forever and a day.

Authors:

Stefano Duranti Siemens Digital Industries
Dominic Jones Siemens Digital Industries
Yongzhe Zhang Siemens Digital Industries
Graham Goldin Siemens Digital Industries