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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 a compact temperature control device to cool down hot exhaust gas coming out of an aftertreatment emission control system. Active DPF (Diesel Particulate Filter) regeneration is required for aftertreatment emission controls to meet the 2007 EPA (Environmental Protection Agency) PM(Particulate Matter) standard. However, regeneration of the DPF temporarily elevates temperatures in the filter to eliminate accumulated soot. This can increase the temperature of the exhaust gas. The temperature control device in this paper draws ambient air into the hot exhaust stream and mixes them together in such a fashion to maximize temperature drop and minimize back pressure for a limited space without any moving parts or supply of extra power. The simple and compact design of the device makes it a cost-effective candidate to retrofit to an existing aftertreatment system.

Several practical devices to reduce aerodynamic drag on a typical class 8 line-haul tractor-trailer application were evaluated last year by this author and Fongloon (Peter) Pan in SAE 2007-01-1781 [Reference 1]. Those evaluations were conducted via reduced scale wind tunnel testing and focused on three areas within the tractor-trailer system: tractor-trailer gap, trailer sides and trailer aft body. This paper builds on our previous work, and presents the results of full scale, on-road fuel economy tests of a select sub-set of those devices. The on-road fuel economy testing was accomplished in accordance with SAE Type II (J1321) test procedure [Reference 2]. An 11.5% improvement in highway fuel economy was demonstrated for a select combination of devices.

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.