Roberto Berlini Rodrigues da Costa

Numerical Analysis of a Torch-Ignition System for an Internal Combustion Engine

Torch ignition systems in spark-ignition engines represents an interesting option in the efforts to reduce pollutants emission and specific fuel consumption. Based on this idea, this paper presents a 3D model of a prechamber created for a spark-ignition engine and focuses on the numerical analysis of the fluid flow inside the modified chamber. This kind of analysis is very important once it allowed evaluating aspects like turbulence parameters, pressure inside the chamber and prechamber, fluid recirculation and a possible prechamber’s geometry for the engine. The studies were done in a four valve Single Cylinder Research Engine – SCRE. For the numerical modeling and fluid flow investigation was used STAR-CD software. Results show higher values of tumble ratio and kinetic energy with the prechamber.

Ethanol Lean Combustion Characteristics of a GDI Engine

In the present study, ethanol combustion analysis was carried in a wall guided type GDI engine, to achieve combustion stability under lean burn operation and to expand the flammability limit for increasing engine efficiency. Tests were performed at constant engine speed, load and injection pressure (1000 rpm, NIMEP = 3 bar, 100 bar), for a wide range of injection, ignition and mixture formation parameters. NISFC, combustion stability, PMEP and burn duration were evaluated at each excess air ratio. An improvement on fuel economy and, consequently, increased engine efficiency was achieved for excess air ratios of λ = 1.1 and λ = 1.2.

Macroscopic Analysis of Spray Development Using Direct Injection for Studying Ethanol Fuel Behavior

A great difficulty in spray analysis is the intrinsic subjectivity in the manual measurements of macroscopic spray characteristics. Within its contexts this work has the main objective to demonstrate a systematic methodology for the spray analysis adopted for acquiring the data results based on numerical criterion dealing with the numerical matrices that represent the spray images. The results shown in this work refers to EXXSOL D60 injection, a tested fluid used to simulate ethanol spray characteristics. The characteristics analyzed were spray penetration, spray pattern at various moments after start of injection and the total volume of the cone spray also as a function of time. The methodology applied uses the numerical matrices of images in different stages of injections. A computational routine written in Matlab environment deals with the numerical matrices of the spray images to localize the spray boundaries based on a numerical criterion. All the subsequent analysis is then performed with the boundaries location data in hand. The results show higher growth of penetration in the beginning of injections, higher displacements of the bottom part of the spray also in the beginning of injections and a linear growth of spray volume injected. The importance of all the results acquired in this work demonstrated that the proposed methodology is suitable for spray analysis.