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The article presents calculations of thermal and mechanical loads of the piston, consisting of two parts: steel and aluminum. The calculations were made using FEM in the Abaqus software. The piston is characterized by a split construction and was equipped with a cooling oil channel. The piston will be used in an aircraft diesel engine characterized by opposite piston movement. The presented geometry of the piston is the next of the ones being developed earlier and contains preliminary assumptions as to the size and main geometrical dimensions. The thermal boundary conditions of the simulation tests assumed defined areas of heat reception surface and heating of the piston by defining a temperature map on its crown. The results of these studies were presented in the form of temperature distribution and heat flux on the surface of the tested element. The strength boundary conditions assumed a mechanical load in the form of pressure resulting from the pressure in the combustion chamber applied to the piston crown surface and the opposite pressure defined on the support at the surface of contact between the piston and the piston pin. The results of these tests were presented in the form of stress distribution on the surface of the tested element. As a result of the analyses carried out, the results constituting the basis for further modernization of the piston geometry were obtained.

The article presents an analysis of the design of cooling liquid pumps for a compression-ignition aircraft engine. A 100 kW twin- charged, two-stroke, liquid-cooled engine has 3 cylinders and 6 opposed-pistons. In the first part of the study, the amount of heat needed to be removed by the cooling system was estimated to obtain the required volumetric flow rate. Then, the design of automotive cooling liquid pumps for compression-ignition engines with a Common Rail power supply system and power of about 100 kW was analyzed. The aim of the analysis was to select a suitable pump for applications in the aircraft compression-ignition engine. 5 constructions of different shape, diameter and width of the working rotor were selected. The pressure and volume flow rate were determined for a given rotational speed of the pump on a specially built stand. The operation maps of individual pumps were created to select the most efficient types of pumps.

The article presents assumptions of the one-dimensional model of the ASz-62IR aircraft engine. This model was developed in the AVL BOOST software. The ASz-62IR is a nine cylinder, aircraft engine in a radial configuration. It is produced by the Polish company WSK “PZL-Kalisz” S. A. The model is used for calculating parameters of the fuel stream and the air stream in intake system of the engine, as well as for the analyses of the combustion process and the exhaust flow to the external environment. The model is based on the equations describing the isentropic flow. The geometry of the channels and all parts of the model has been mapped on the basis of empirical measurements of the engine elements. The model assumes indirect injection where the gasoline was used as a fuel with the calorific value of 43.5 MJ/kg. The model assumes a mixture of a stoichiometric ratio of 14.5. This model is only part of the overall the ASz-62IR engine model. After the simulation tests on the full model the obtained results confirmed the correctness of the model used to create the mixture. It was found that the AVL BOOST software is good for the implementation of this type of work.

This paper investigates toxic emissions emitted by ASz62-IR radial engine under training flight conditions. The registered selected flight parameters enabled the distribution and share of operating times in given stages of engine operation. The individual toxic substances were calculated in line with an AVL BOOST model of this engine. The results of the chassis dynamometer measurements performed at WSK PZL-KALISZ S.A., an engine manufacturer, enabled us to calibrate the model in terms of its performance, i.e. torque and overall efficiency as a propeller characteristics. Later, a model for toxic emissions was calibrated. Defined by crankshaft speed and intake manifold air pressure, operating points reflect real flight values. For each case study, mass flow rates of individual toxic substances were calculated. The distribution of operating times in individual stages of the operation of Antonov An-2’s engine registered during a training flight enabled us to calculate a total mass of toxic substances.

The paper presents an analysis of the fluid flow in the cooling system of an internal combustion engine with oposite pistons.The purpose of the work was to optimize the flow of fluid through the channels located in the engine block. Simulation studies and subsequent iterations were performed using Ansys Fluent software. Two-equation k-epsilon turbulence model was used in the simulation model. Boundary and initial conditions were taken from previously made simulations conducted in AVL Boost software. The average wall temperature of the cylinder and the temperature of the outer walls of the cylinder were assumed for simulations. The results of the analyzes were graphically illustrated by the speed streamline distribution of velocity fields and temperature.

The article presents the results of simulations research carried out, using Finite Element Method. The simulations were made in the Abaqus software. Calculations were made on the connecting rod of opposed piston engine. The connecting rod was subjected to a compression tests. Different versions of the boundary conditions in the form of load forces and pressure distribution acting on the small end of the connecting rod were presented. Depending on the load distribution acting on the connecting rod small end, different distributions of stresses in the connecting rod geometry were obtained. All studies were performed for the same geometry, the same mesh grid, and for the same value of compressive force (research could be considered as comparable). Changing the size and distribution of stresses in the connecting rod, evidence the impact of the adopted boundary conditions of the load distribution on the calculation results. It is important for the use of modern simulation tools in the design process of new mechanical parts.

The article presents the results of simulations research carried out, using Finite Element Method. The simulations were made in the Abaqus software. Studies were related to the reduction and improving of stress distribution in the connecting rod of opposite pistons combustion engine. The connecting rod has been developed in a 3D environment in the Catia software, then imported into the simulation tool, in which stress tests were performed. The connecting rod was subjected to a compression and stretching tests. Boundary conditions of forces used in simulation tests have been developed on the basis of the dynamic model created in the MSC Adams software. The study included nine iterations of geometric changes of connecting rod. Shape as well as properties such as parametric dimensions (rod length) were changed. The changes were dictated by the reduction of the maximum values of the stresses and the size of the fields with large stress values. As a result of the simulations, the improvement of the connecting rod strength was obtained by its geometrical change (which was obtained by reducing the stress fields).

The misfire phenomenon is particularly unfavourable in aircraft engines because it affects the stability and reliability of work. This paper presents the algorithm for detecting ignition failure in a radial aircraft engine. The Crankshaft Velocity Fluctuation method was applied, which consists in analysing changes in the crankshaft speed signal as a function of time. A zero-dimensional model of the aircraft engine was developed in order to perform the research. The validation of the model was performed using the results from the test bench. The model was subjected to simulation tests in fixed operating conditions. Based on the engine speed signal obtained as a result of the simulation, the normalized second derivative of the signal was determined based on the adopted algorithm. On the basis of this derivative, a criterion was defined to assess the occurrence of the misfire phenomenon. The results of the calculations can be compared in future with the results of the real engine tests.

This paper presents an analysis of the results of simulation studies of optimisation of water channel geometry placed in the head of an opposed-piston three-cylinder engine. For this purpose, six computation cases were prepared, differing in shape and cross-section field of channels located along the axis of one of the cylinders. The research was conducted by means of Ansys Flutent software. The conditions of initiation and boundary have been obtained from previous studies using AVL Boost RT software. A fixed temperature was assumed on the cylinder wall and a fixed temperature was assumed for the coolant at the inlet to the model. The studies were carried out for the model of the designed engine, which carries out a two-stroke diesel cycle. The engine will be equipped with direct injection of diesel fuel. On the basis of the conducted analysis of the test results, the flow velocity distributions and distributions of speed fields of the working medium in the critical cross-sections, the distribution of temperature and heat flow fields were prepared. Pressure drops and heat dissipation were also determined for individual models. This provided the basis for the determination of the influence of the rib's transverse geometry shape on the amount of heat received from the cylinder's smoothing walls.

The nozzle is an element of the rocket engine in which the potential energy of gases generated during combustion is converted into the kinetic energy of the gas flow. The design parameters of the nozzle have a decisive influence on the ballistic characteristics of the engine. Designing a nozzle assembly is therefore one of the most responsible stages in developing a rocket engine design. The paper presents the results of the simulation of three types of rocket propulsion nozzles. Calculations were made using CFD (Computational Fluid Dynamics) in ANSYS Fluent software. The analyzed types of nozzles differ in shape. The analysis referred to conical nozzle, a bell type nozzle with a conical supersonic part and a bell type nozzle. Calculation results are presented as pressure, velocity, turbulence kinetic energy and eddy viscosity distributions in the longitudinal section. The results show that the cone nozzle generates strong turbulence in the critical section, which negatively affects the flow of the working gas. In the case of a bell nozzle, the transformation of the wall caused the elimination of flow disturbances in the critical section, which reduced the probability of waves that can form before or after the trailing edge. The most sophisticated construction, the bell-type nozzle, allows for maximizing performance without adding extra weight. The bell type nozzle can be used as a starter and auxiliary engine nozzle due to its advantages.

The paper presents CFD analysis of fuel flow in the CNG injector. The issues such a pressure drop along an injector channel, mass flow through the key sections of the injector geometry, flow rates, the impact of the needle shape on the deflection of the sprayed gas cone and the impact of the wall head are analyzed in the article. The simulation was made in the transient states conditions for full injection process, including the opening and closing of the injector. An injection time of 6 ms, velocity of 0.33 mm/ms and a lift of 0.5 mm were selected for opening and closing of injector based on experimental test. The simulation shows that the volume inside the injector is a kind of fuel accumulator, and the opening process of the needle influence the flow parameters in an inlet cross-section after a certain time, depending on a channel cross section. The calculations allowed to select the ratio of an injector duct cross sectional area to the aperture area of the injection capable of the reducing pressure loss. The unusual location of the injector in the socket of a glow plug in the Andoria ADCR engine makes a stream be impaired by a part of the head. This research result would be useful in developing an injector construction which will be used for an investigation of CNG addition into diesel engine.

This paper presents the research results on a 1D model of an opposed-piston two-stroke aircraft Diesel engine. The research aimed at creating a model of the engine in question to investigate how engine performance is affected by the compressor gear ratio. The power was constant at all the operating points. The research results are presented as graphs of power consumed by the compressor, compressor efficiency and brake specific fuel consumption. The optimal range of compressor gear ratio in terms of engine efficiency was defined from the research results.

The analysis of the distribution of thermal energy generated during the combustion process in internal combustion engines and the estimation of individual losses are important regarding performance and efficiency. The article analyses the energy balance of the designed two-stroke opposed piston diesel engines with offset, i.e. the angle by which the crankshaft at the side of exhaust ports is ahead of the crankshaft at the side of intake ports. Based on the developed zero-dimensional engine model, a series of simulations were performed in steady-state conditions using the AVL BOOST software. The values of individual energy losses, including cooling losses, exhaust gas losses, friction losses were obtained. The influence of decreasing and increasing the offset on the performance of the tested engine was analysed.

The paper describes simulation tests of a gas injector with the use of numerical fluid mechanics. The tests were carried out on a CNG flap-valve injector which was connected with an inlet manifold by an additional injection pipe. Such a model was identified and calibrated on the basis of the test stand research. The paper presents the tests results in transient conditions (during valve opening and closing) and in a steady-state flow. The analysis concerns pressure and gas velocity flow in selected points and sections of the injector and the injection pipe. The processes occurring in selected areas of the injector have been presented. Moreover, areas essential for the useful characteristics of the injector have been illustrated.

The article presents vibration simulation studies of a crankshaft used in internal combustion engine. The simulation was performed using FEM method. The study was conducted in Abaqus software, and a shaft model was implemented in Catia v5. The influence of a mesh element size on the results of obtained calculations was analysed. A shaft which will be used in the ultralight aircraft engine was the subject of research. Results show the first 10 frequency modes and 12 grid examples for various element sizes, from 9 to 1.3 mm. Moreover, the effect of mesh size on the obtained results is presented. It has been proven that the maximum error for two extreme results (the densest and sparsest grid) is approximately 1.4%; therefore, it is justified to carry out calculations of own vibration on a fatal grid. Results presented herein will be used in the future work on the crankshaft geometry modifications.

We present the statistical nonlinear analysis of time series applied to indicated combustion pressure. Using nonlinear methods we analyzed dynamics of a multi cylinder aircraft radial engine in the presence of cyclic perturbations in a single cylinder. The perturbations have been caused by variation of an air/fuel ratio via injection timing. Identification of the disturbed cylinder has been done successfully by adopting wavelet and multifractal analysis. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)