Optimization Study of Exhaust Diffuser for Semi-Trailer Truck

"Design and evaluation of Semi Trucks are an important but expensive and time-consuming part of the product development process because of large design variations and low production volumes per variant. In this article, we focus on the design of the exhaust tip assembly of the truck and in particular on the exhaust pipe tip geometry immediately upstream of the exhaust diffuser. The design intent of the exhaust tip is to minimize the temperature of the exhaust diffuser in order to maximize durability of components and reduce environmental concerns. A design process wherein different geometric shapes of the exhaust tip prototypes are subject to testing in a test bench is expensive and time consuming. An alternative and promising approach investigated in this study is the use of a Computational Fluid Dynamics (CFD) simulation based methodology used to evaluate various exhaust geometries virtually leading to an optimal geometrical design. In this investigation, we use a coupled PowerFLOW? and PowerTHERM? methodology to simulate exhaust flow in a truck for various exhaust tip geometrical shapes. The shapes were generated using morphing technology and the design objectives of the study is to minimize the exhaust diffuser temperature while minimizing the pressure drop of the exhaust system. By execution of an automated optimization algorithm, we were able to generate a final design where the diffuser temperatures were lower than that of the baseline design by more than 10% while maintaining the exhaust pressure drop of the baseline design. "