An investigation of air-swirl design criteria for gas turbine combustors through a multi-objective CFD optimization

- A multi-objective optimization of a gas-turbine combustor is performed.
- An efficient model is proposed for the design optimization process.
- Entropy generation minimization is considered with other conventional targets.
- The Swirl number design criterion is revisited based on the new analysis.

In this study, the non-premixed swirl-stabilized flame in a gas turbine combustor is simulated. For this purpose, first, an efficient model for the simulation of combusting flow in real combustor liners is proposed which is appropriate for the computationally expensive design optimization process. Then, this model is used to perform a multi-objective optimization of a real combustor based on the combustion efficiency, pattern factor, pollutant (CO and NO) emission, and entropy generation minimization targets. After investigating the effect of the Swirl number on each objective through response surfaces and sensitivity analysis, the optimal case is introduced by the decision making process. The results show that the base case Swirl number, chosen based on a well-known correlation, is the best case if only the combustion efficiency is maximized. However, the overall optimal case which is the trade-off among the above four objectives possesses a Swirl number 44 percent smaller than the base case.