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The need of upfront modeling, simulation and design optimization has been ever increasing during full vehicle product development process. The overall vehicle system and component subsystem performances remain critical considerations for making final product release decision. With these challenges in mind, the work of this paper discusses the development of feasible CAE methods, tools, and processes for multi-objective design optimization. A full integrated tractor trailer truck vehicle is used as an example to demonstrate this capability. The proposed approach allows several design objectives to be simultaneously optimized, which might otherwise be extremely difficult to achieve with experimental methods.

Truck underhood thermal management has become a critical design parameter to meet the increasingly stringent U.S. federal EPA (Environmental Protection Agency) diesel emissions standards. Both heat exchanger modules and vehicle design details have significant impact on the cooling performance. This paper introduces an integrated numerical modeling approach utilizing one way coupled solution combining 3-dimensional finite volume computational fluid dynamics (CFD) method and 1-dimensional simplified system model to simulate full complicated airflow and heat transfer activities. The results are validated against experimental data based on some selected actual vehicle operating conditions for two designs configurations including a new and improved cooling module design.

This paper presents the impact of a number of practical add-on devices on reducing aerodynamic drag for tractor/semi trailer combination trucks. The evaluations were conducted via reduced scale wind tunnel testing. Sub-scale testing is a very efficient and accurate method to conduct trade studies and evaluate alternate shapes. The test focused on three areas within the tractor-trailer system: tractor-trailer gap, trailer sides and trailer wake. A 23% aerodynamic drag reduction was demonstrated by utilizing trailer skirts, base plates and lengthened side extenders and air fairing. A 20% drag reduction was also demonstrated for several combinations of devices.