No abstract

The paper presents a description of geometric models, computational algorithms, and results of numerical analysis of charge exchange in an opposed-piston two-stroke engine. The research engine is a newly designed internal diesel engine. This unit is composed of three cylinders in which operate three pairs of opposed-pistons. The engine generates a power output equal to 100 kW at a crankshaft rotation speed of 3800-4000 rpm. The numerical investigations were carried out using ANSYS FLUENT solver. The geometrical model includes an intake manifold, a cylinder and an outlet manifold. The study was conducted for a series of modifications of manifolds and intake and exhaust ports to optimise the charge exchange process in the engine. In addition, we attempted to verify the effect of the combustion chamber shape on the charge exchange process in the engine. The calculations specified a swirl coefficient obtained under steady conditions for fully open intake and exhaust ports as well as the CA value of 280° for all cylinders. In addition, mass flow rates were identified separately in all of the intake and exhaust ports to achieve the best possible uniformity of flow in particular cylinders. The paper includes comparative analyses of all of the intake and exhaust manifolds of the designed engine.

The article presents the tests results of the prototype design of hydraulically assisted injector that is designed for gas supply into diesel engines. The construction of the injector allows for its positioning in the glow plug socket, so that the gas is injected directly into the combustion chamber. The cycle analysis of the four-cylinder Andoria ADCR engine with a capacity of 2.6 dm 3 for different crankshaft rotational speeds allowed to determine the necessary time for fuel injection. Because of that, it was possible to determine the required mass flow rate of the injector, for replacing as much of the original fuel by gaseous fuel. To ensure a high value of flow inside the injector, supply pressure equal to 1 MPa was applied. High gas supply pressure requires high value of valve opening forces. For this purpose a injector with hydraulic control system, using a liquid under pressure for the opening process was designed. On the basis of air pressure measurements in the flow line after the injector, the analysis of opening and closing of the valve was made. Measurements of outflow mass of the injector were also carried out. The results showed that the designed injector meets the requirements necessary to supply ADCR engine with CNG fuel.

The paper reports on the process of modelling a high-pressure common rail pump designed to supply a two-stroke compression-ignition engine, which includes the presentation of methodology for model construction and results of simulation tests. A one-dimensional model of the pump was developed in the AVL Hydsim environment. A single-section positive displacement pump driven by a double cam was used for modelling. The developed model enables simulation of pump operation in various conditions defined by shaft speed, pumping pressure, settings of pump executive elements as well as fuel properties. The obtained results were compared with the results of bench tests and theoretical calculations. The analysis included the flow rate fuel overflow and changes in pumping pressure depending on the fuel dispenser settings. The model will also be used to build a complete fuel supply system model consisting of an injector model, a rail model and a control system model. The research is carried out with a view to optimising individual components and the operation of the entire supply system, taking into account the regulation of pumping pressure and synchronisation of the pumping process with fuel injection cycles.

Abstract. A proper design of the compression ignition engine fuel system requires various fuel injection methods analysis. Direct and indirect CNG injection process simulation research was conducted. The results allow a mixture homogeneity analysis and its impact on combustion process and heat transfer. For an indirect injection the injector is placed in intake channel and the injection is performed during an intake stroke. For a direct injection the specially designed injector is installed in the glow plug position. The analysed case is set for 20% energetic ratio of diesel fuel and 80% of methane fuel. In order to perform the calculations a special combustion model has been implemented that allows duel-fuel combustion in a compression ignition engine.