Optimization of Design and Technology of Injector Nozzles in Terms of Minimizing Energy Losses on Friction in Compression Ignition Engines

The operation of injection apparatus in self-ignition engines results from the design, manufacturing technology and wear and tear during operation. The technical state of the injector apparatus significantly affects the engine performance, fuel consumption, toxicity and smoke opacity of outlet gases. The most unreliable element of the injection apparatus is the injector nozzle, the quality of which depends on the quality of construction and production, operating conditions and the of the fuels used, etc. One of the design parameters of the injector nozzles, determining the technical state is the geometry of the nozzle holes. An attempt was made to optimize the selection of the dimensions and surface condition of the spray holes to significantly affect the flow properties of the injector nozzles and, consequently, to decide on the size and form of fuel dosed streams to individual cylinders of a self-ignition engine and the quality of fuel atomization. In work, a simulation model was developed, and the pressure losses and the mass fluid of the injected fuel were minimized for selected significant geometric features, taking into account the influence of operating conditions. With the use of Mathematica software, simulation optimization methods and methods based on evolutionary algorithms were elaborated.

Modal Analysis of Fuel Injection Systems and the Determination of a Transfer Function Between Rail Pressure and Injection Rate

A detailed analysis of a common rail (CR) fuel injection system, equipped with solenoid injectors for Euro 6 diesel engine applications, has been performed in the frequency domain. A lumped parameter numerical model of the high-pressure hydraulic circuit, from the pump delivery to the injector nozzle, has been realized. The model outcomes have been validated through a comparison with frequency values that were obtained by applying the peak-picking technique to the experimental pressure time histories acquired from the pipe that connects the injector to the rail. The eigenvectors associated with the different eigenfrequencies have been calculated and physically interpreted, thus providing a methodology for the modal analysis of hydraulic systems. Three main modal motions have been identified in the considered fuel injection apparatus, and the possible resonances with the external forcing terms, i.e., pump delivered flow rate, injected flow rate, and injector dynamic fuel leakage through the pilot valve, have been discussed. The investigation has shown that the rail is mainly involved in the first two vibration modes. In the first mode, the rail performs a decoupling action between the high-pressure pump and the downstream hydraulic circuit. Consequently, the oscillations generated by the pump flow rates mainly remain confined to the pipe between the pump and the rail. The second mode is centered on the rail and involves a large part of the hydraulic circuit, both upstream and downstream of the rail. Finally, the third mode principally affects the injector and its internal hydraulic circuit. It has also been observed that some geometric features of the injection apparatus can have a significant effect on the system dynamics and can induce hydraulic resonance phenomena. Furthermore, the lumped parameter model has been used to determine a simplified transfer function between rail pressure and injected flow rate. The knowledge obtained from this study can help to guide designers draw up an improved design of this kind of apparatus, because the pressure waves, which are triggered by impulsive events and are typical of injector working, can affect the performance of modern injection systems, especially when digital rate shaping strategies or closely coupled multiple injections are implemented.

THE INFLUENCE OF ADDED WATER ON FUEL INJECTOR WEAR IN A DIESEL ENGINE

The article presents the problem of the wear of the components of injection apparatus of a self-ignition engine during the addition of water. The observer was subject to an injector from the KIPOR KDE3500E generator set engine. The tests carried out consisted in observing the atomizer after 120 minutes of running the engine powered with diesel oil and after working at the same time but with the addition of water to the intake manifold.

Fully predictive Common Rail fuel injection apparatus model and its application to global system dynamics analyses

A fully predictive model of a Common Rail fuel injection apparatus, which includes a detailed simulation of rail, pump, piping system, injectors and rail pressure control system, is presented and discussed. The high-pressure pump and injector sub-models have been validated separately and then coupled to the rail and pressure control system sub-models. The complete predictive model has been validated and applied to investigate the effects of the dynamics of each component of the injection apparatus on the rail pressure time history. Variable timing of the high-pressure pump delivery phases has also been considered, and the influence of this parameter on the injection performance has been analysed for both single- and multiple-injection events. Furthermore, the injection system dynamics during the transients between steady-state working conditions has been investigated in order to highlight the role played by the dynamic response of the pressure control system on the rail pressure time history.

Pore Structure and Mechanical Properties of ZrC/SiC Multi-Components Modified C/C Composites

The ZrC/SiC multi-components modified C/C composites were prepared by using a hybrid precursor containning polycarbosilane and organic zirconium-contained polymeric precursor as impregnant and C/C composites of low density as preform. The porosity, microstructure and mechanical properties of samples were characterized with mercury injection apparatus, scanning electron microscopy and universal electron testing machine respectively. The results show that the porosity and average pore diameter decrease firstly and increase subsequently with the increase of organic zirconium content of the precursor. When the content of organic zirconium is 50%, the porosity and average pore diameter reach minimum which were7.27% and 0.0795um respectively. The most probabilistic pore diameter shifted from 10-100um to 1-10um at the same time; Meanwhile, the flexural properties also increases and drops immediately as the content of organic zirconium in the precursor adds. When the content of organic zirconium is 25%, the flexural strength reaches maximum of 245.20MPa.The improved flexural properties is attributed to the proper bonding of fiber-matrix interface and the low porosity of samples.

Measuring Isostatic Pressing Strength of Hollow Glass Microspheres’ by Mercury-Injection Apparatus

In this passage, we introduce the theory and the method of measuring isostatic pressing strength of hollow glass microspheres’ by Mercury-injection Apparatus. We show in detail that how to measure isostatic pressing strength of hollow glass microspheres’ We also get some results in this way by comparing with the results of 3M’s，and the error is less than 2.85% .We analysize the reason of the error. This way is simple and accurate. Its repeatability is very good and it’s suitable to measure isostatic pressing strength of all kinds of hollow glass microspheres’. The requirements of production and scientific research could be satisfied.