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The physical properties of ethanol make difficult the cold start of engines using only this fuel. The solution most adopted consists in the utilization of an auxiliary gasoline reservoir and the injection of this fuel when it is necessary. In this work, it is presented a new concept for the cold start system using gasoline injection that consisted in the use of a mini fuel rail, so called because of its compact layout that through the use of calibrated orifices allows the fuel injection as jets directly in the admission valves. It presents the CFD simulations, conducted to improve the system performance and the bench laboratory tests performed to evaluate the fuel distribution and to analyze the fuel jets.

This paper intends to describe spray predictions using CFD technologies for spray formation and evolution on fuel blend. Spray formation was simulated in ANSYS CFX using a Lagrangian model. The primary breakup model used in this study is a variation of the well-known BLOB method. The Cascade Atomization Breakup (CAB) and Modified Cascade Atomization Breakup (MCAB) models for secondary breakup were used. Simulations using different Rosin Rammler distributions were carried out. N-Heptane was used as reference fuel for experimental tests. A high degree of consistency between experimental data and numerical analysis for spray propagation characteristics was found. The methodology has been developed on Heptanes, aiming to extend the methodology to other fuels, i.e. ethanol.