International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

1D simulation has significantly supported the process of developing a diesel ignited high-pressure gas direct injection combustion concept, thus facilitating promising investigations at the SCE. It has been applied to a variety of tasks such as designing the media supply system, pre-optimizing engine operating parameters and developing the safety concept discussed in this paper. Application depends on two simulation models in particular: one validated MCE model and one SCE model enhanced in the course of the concept design phase. Since the MCE model can reliably reproduce the behavior of a full engine with single-stage turbocharging, it played a critical role in determining the boundary conditions for both the 3D-CFD simulation and the simulations with the SCE model. The SCE model, on the other hand, includes all components relevant for the test bed and thus permits both a reliable design of the gas path and the development of a safety concept, which is of remarkable importance for high-pressure gas applications. With regard to the safety concept, this paper presents and discusses the difficulties in detecting injector malfunction and different detection strategies.

The tools for statistical expert evaluation of the influence of alloy composition elements on pre-selected quality indicators are described in order to improve the mechanical properties of the products through the prism of project management. Through the defined approach, it is possible to define a composition providing relatively best meanings of the values of the selected mechanical indices.

Future emission legislation will be increasingly stringent. The current German TA Luft limit for nitric oxide (NOx) emissions from large gas engines is 500 mg/mn³ @ 5% O₂ and there is a clear trend toward further reductions. One possible strategy to meet these limits for gas engines is exhaust gas recirculation (EGR). This paper focuses on the application of 1D simulation to a variety of different tasks in gas engine development. First, the basic effects of EGR in gas engines are explained by discussing several 1D simulation results from two 1D simulation models for a large stationary gas engine. A detailed single cylinder engine model is used to study the interaction between the pre-chamber and the main combustion chamber. The boundary conditions are provided by a multicylinder engine model that includes a turbocharger. Based on simulation calculations with both models as well as measurements from a single cylinder research engine, the thermodynamic conditions in the combustion chamber and the gas dynamics are analyzed.

The development of highly efficient combustion concepts for internal combustion engines requires a suitable development methodology. In recent years, the LEC has created LDM (LEC Development Methodology), which is based on the intensive interaction between simulation and experimental investigations on single cylinder research engines. As new engine concepts are developed, many operating parameters are first defined and optimized with a 1D multicylinder engine model. This model illustrates the full complexity of the engine with its geometry, turbocharging and combustion parameters. The design of experiments (DoE) method is used in connection with 1D simulation to find the optimal engine configuration as well as parameters related to the combustion process, i.e. valve timing, compression ratio, ignition timing, excess air ratio. The maximum engine efficiency is found by taking into account the boundary conditions (brake mean effective pressure, turbocharger efficiency), where NOx level and knock limit are constraints.

Processing of thin-walled parts with large dimensions in conditions of wide range production poses a number of technological problems. One of the most important among them is the provision of alignment on both sides of the hole who passing through the opposite walls of the part. Is essential the alignment of the spindles while processing of the hole , if used for this purpose machining center with two horizontal spindles . In the publication is presented research about possibilities to solve the problem by controlling of spindles alignment. For this purpose are carried out contact coordinate measurements of the hole in one spindle using 3D touch probe which is fixed in the other spindle.

In the publication are presented studies to determine the accuracy of the group approach in calculating the cost of technological engineering products. For this purpose, the cost price of a specific item is calculated by applying the developed approach and the group is compared with the actual cost. The results obtained show that the use of group approach enables a comparatively fast and sufficiently precise calculation of the technological cost of machine products.

Presented is a method for determining the tolerances in geometric precision of machining centers in working conditions. The method is based on the implementation of coordinate measurements with contact measuring head. The measurements are performed on special prismatic detail – caliber attachable with relatively low grade precision guidance on the machine table. In the publication are presented experimental studies and the results obtained. The conclusion is that the developed method, the mathematical model and caliber are suitable for the determination of some basic elements of geometric precision of machining centers in working conditions. At the same time provides a satisfying user accuracy, cost and performance.