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The electrical control common-rail injector (CRI) is a key component in marine diesel engines. Herein, a detailed fluid-mechanical-electric-magnetic coupling mathematic model regarding the CRI was established, considering the transient of fuel properties, different structure parameters of the CRI, and the nonlinear magnetization and magnetic saturation of magnetic materials of the high-speed solenoid valve (HSV) for the CRI. This model was verified by comparing the calculated injection rate with the experimental data at different injection pressures, and the good consistencies obtained proved the validity of this model. Based on this model, the effect of different factors on the dynamic response of the injector was investigated to prepare for the optimization.

In this article, the effects on the jet process of natural gas through an outward-opening nozzle were analyzed at different pressure ratios (PR). The visualization and analysis of the jet process was based on Schlieren methods. High-speed Schlieren imaging was used to capture the growth of the transient gas jet in a constant volume vessel (CVV) under atmospheric conditions. The experimental results revealed an increase in the radial and axial penetrations in accordance with an increase in the PR. The jet process of the outward-opening nozzle can be divided into two stages, according to the ratio of the radial penetration to the axial penetration. The spread angle increased with the advancement of the gas jet at the initial phase of the jet process. After this phase, the spread angle decreased to a constant value. The appearance of the constant value is directly related to the PR. The peak velocity increased with an increase in the PR.

In this study theoretical investigations were carried out to determine design and working parameters modifications in order to increase by 20% power output and reduce fuel consumption in a marine two stroke medium speed diesel engine with opposite pistons. To achieve the above aim software packages, such as DIESEL-RK, INJECT and ANSYS, were deployed. The phenomenological multi-zone fuel spray combustion model in DIESEL RK software was refined to take into account complex interactions of fuel sprays and the influence of air swirl in the cylinder on evolution of fuel spays. For this purposes a 3D grid was created with regular cubical cells in the combustion chamber of the engine. The density of mesh was 50 cells across the diameter of the cylinder. In contrast to CFD technique, the transfer of liquid fuel and fuel vapour in the computational grid was carried out using empirical equations which had been validated by other researchers.

A previously developed multi-zone direct-injection (DI) diesel combustion model was implemented into a turbocharged diesel engine full cycle simulation tool DIESEL-RK. The combustion model takes into account the following features of the spray dynamics: Detailed evolution process of fuel sprays. Interaction of sprays with the in-cylinder swirl and the walls of the combustion chamber. Evolution of a Near-Wall Flow (NWF) formed as a result of a spray-wall impingement as a function of the impingement angle and the local swirl velocity. Interaction of Near-Wall Flows formed by adjacent sprays. Effect of gas and wall temperatures on the evaporation rate in the spray and NWF zones. In the model each fuel spray is split into a number of specific zones with different evaporation conditions. Zones, formed on the cylinder liner surface and on the cylinder head, are also taken into account. The piston bowl in the modeling process is assumed to have an arbitrary axi-symmetric shape.