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This study investigated the effects of underhood structure parameters (two types of air ducts, two types of inlet grilles and the opening angle of inlet grilles) on the cooling characteristics of the rear-engine bus; then, the optimum design scheme of the underhood was determined. The air-side resistance load of the cooling system, which is based on fan performance, was selected as the optimization objective. Simulations were created based on a porous media model and standard a k-ε model. The next step was to build a 1D/3D coupling simulation to utilize the advantages of 1D simulation’s fast convergence speed and 3D simulation’s extensive research range. Besides, the use of 1D/3D coupling simulation can efficiently avoid the errors of simulation results which arise from the non-uniform airflow on the cooling module. Results show that the airflow rate of the rectangular air duct increased by 7 to 11percent.

Hydrous ethanol not only has the advantages of high-octane number and valuable oxygen content, but also reduce the energy consumption in the production process. However, little literature investigated the internal flow and cavitation of hydrous ethanol-gasoline fuels in the multi-hole direct injector. In this simulation, a two-phase fuel flow model in injector is established based on the multi-fluid model of Euler-Euler method, and the accuracy of model is verified. On the basis of this model, the flow of different hydrous ethanol-gasoline blends is calculated under different injection conditions, and the cavitation, flow rate, and velocity at the outlet of the nozzle are predicted. Meanwhile, the influence of temperature and back pressure on the flow is also analyzed. The results show that the use of hydrous ethanol reduces the flow rate, compared with the velocity of E0, that of E10w, E20w, E50w, E85w, and E100w decreases by 10%, 12.9%, 17.6%, 20%, and 23.5%, respectively.

Turbocharger is an important method to improve fuel economy of internal combustion engines. Traditional turbocharger matching methods show their limitations that only consider the matching between turbocharger and engine under the single designed operating point. This paper is to study the turbocharger matching based on vehicle performance requirements, in which performance requirements among vehicle, engine and turbocharger system are fully considered. The study is based on a vehicle which is equipped with 1.5L Chinese produced engine. Vehicle powertrain and gasoline engine simulation models were built in one-dimensional simulation software and verified by experiments. According to the vehicle performance, to study the matching under multiple working conditions, new European drive cycle (NEDC), full-load condition and high altitude condition, the matching of four kinds of turbochargers with a gasoline engine were compared respectively.