Design Optimization and Analysis of Advanced Exhaust Systems

Historically, aircraft engines have featured relatively simple axisymmetric exhaust shapes with several moving parts; however, future engine exhaust systems are expected feature compact, sinuous ducts with complex non-axisymmetric shapes, fixed exit areas, thrust vectoring etc., constructed with a minimum number of moving parts. Their exhaust plumes are currently not well understood; however, LES analysis of the exhaust system interior aerodynamics and the plume appears promising. Attention must also be directed towards the structural analysis. The current practice in the aerospace industry is to conduct uncoupled aerodynamic and structural analyses, which is a cumbersome, time consuming and expensive. It results less than optimal final exhaust configurations under tight time and budget constraints. This provides a strong motivation for creating a multi-disciplinary exhaust system optimization environment within which LES modeling of the exhaust flowfield is coupled to structural analyses of the components forming the exhaust system with the objective of minimizing structural component weight and maximizing system performance. Such tools are requisite for supporting the development of next-generation engines and optimizing their designs with regards to maximum system performance, as well as durability from the improved understanding of the structural loads on the exhaust nozzle and duct components leading to weight reduction.