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The air distribution duct with multiple outlets is an essential part of the automotive air-conditioning system in a bus. The estimation of airflow rate in an automotive air-conditioning duct is typically very complicated due to large variations in cross-sectional area and abrupt changes in flow direction, as well as unbalanced distribution of the flow. This paper describes numerical simulations performed for two simplified air conditioning ducts used in a medium bus. The three dimensional Navier-Stokes code was used to evaluate the overall pressure, velocity field, and distribution rate at each diffuser according to the change of cross-sectional duct area and diffuser area. In addition, a one-dimensional program based on the Bernoulli equation was developed to obtain the optimum diffuser area required to equalize discharge flow rate at each outlet. The results of this analysis were compared to the results obtained from experimental measurement and CFD simulation.

At the initial design stage of a new vehicle, chassis layout has the most important influence on overall vehicle performance. Most chassis designers have achieved target performances by trial and error as well as by individual know-how. Accordingly, a general procedure for automatically determining the optimum location of suspension hard points with respect to the kinematic characteristics needs to be created. In this paper, a method to optimize the toe angle in the double wishbone-type front suspension of a four-wheel-drive vehicle is presented using design of experiments, multibody dynamic simulation, and an optimum design program. The handling performances of two full vehicle models having the initial and the optimized toe angle are compared using a simulation of a single lane change maneuver. Front and rear suspensions are modeled as rigid bodies connected by kinematic joints using DADS.