A novel multi-parametric methodology for design and multi-objective optimization of turboshaft airframe/engine integrated exhaust system

This study introduces an improved mathematical model, referred to as 4k, for the design of turboshaft airframe/engine integrated exhaust systems. This method allows independent adjustment of the upper and lower ridge line shapes and is defined by four continuous geometric variables ( k 1 , k 2 , k 3 , k 4 ), making it highly suitable for optimization studies. In this study, five cases were developed using 4k method and assessed through experimentally validated numerical simulations, focusing on the variables' impact on the exhaust system's thermal and mixing performance. The study's findings indicate that the streamwise vortices and annularly arranged normal vortices influence each other and are directly affected by the nearby pressure; the formation of annular normal vortices inevitably affects the integrity of the streamwise vortices. Moreover, the regulation of pressure and temperature distribution in turboshaft airframe/engine integrated exhaust systems was revealed. Finally, using the 4k method, surrogate models were developed to conduct multi-objective optimization, resulting in a set of recommendations for the design of turboshaft airframe/engine integrated exhaust system.