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The paper describes an experiment aimed at specifying the effects of adding Brown's gas (HHO gas) in automotive engines operating at idle speed. HHO gas was obtained from the author's parallel plate generator with a single central anode and two side cathodes separated by six neutral plates. The generator was powered by an external power source (power supply unit) and produced a constant HHO gas flow rate in the experiment. The so obtained HHO gas was added to the engine intake systems of 5 passenger cars – three SI engines, i.e. Fiat Cinquecento, Renault Twingo, and Opel Corsa and two CI engines, i.e. Skoda Octavia and Opel Combo. The engines operated in idling conditions. The MAHA MGT5 analyzer measured the concentrations of CO, HC, NOx in the exhaust gases of those cars first fueled by stock fuel (SF) only and then with added HHO gas, i.e. SF + HHO. The ambient conditions remained constant. The results show that fueling with an HHO gas additive has an impact on emissions: CO and HC concentrations in the exhaust gases were reduced in the most of the cases; NOx concentration was reduced in the SI engines but increased in the Diesel ones. Adding HHO gas to the engine intake system of the Fiat Cinquecento operating at idle slightly deteriorated the combustion process there (the impact of carburetor-based supply without feedback). Although HC concentration was lower by 24%, the amount of CO increased by 34% and nitrogen oxides hardly changed. CO concentration if any decreased in the other vehicles. The concentration of HC in the exhaust gases of each of the vehicles show that adding HHO gas to the original fuel, regardless of fueling methods and techniques, reduces the concentration of unburned hydrocarbons: by more than 20% in the Fiat and by about 40% in the others. The NOx concentration in the exhaust gases of each of the vehicles show that after adding HHO to the original fuel, the amount of NOx depends on a fueling method. In the SI engines with indirect injection, adding HHO gas to the intake system reduced the NOx concentration. In the Fiat with a carburetor without feedback, the NOx concentration remained practically unchanged but it increased in the CI engines if HHO gas was added to their intake systems. Image 1 • Engine fueling with an HHO gas additive has an impact on emissions. • HHO added to the SI and CI engines improves the purity of exhaust gases at idle. • CO and HC concentrations in the exhaust gases were reduced. • At idle NOx concentration In CI engines increases and in SI engines decrease. • HHO added to SI engine without feedback control deteriorated the combustion process. [ABSTRACT FROM AUTHOR]

We suggest an approach for detecting and identifying ignition failure on a internal combustion engine used in aviation through the analysis of vibration time series. The research is carried out at the experimental stage, where time series of vibrations are collected from sensors installed in various parts of the facility at various rotational speeds and various operating conditions (no failure/failure of a selected piston). The time series were decomposed into periodic components centered around dominant frequencies. Data with greater dimensionality was statistically described using linear and non-linear indicators in short time windows, and labeled accordingly. Instead of examining the statistical significance of the characteristics of individual groups, machine learning classification methods were used, which allowed to distinguish the operating state of the engine (damaged/undamaged), and also to identify a specific unfired cylinder. The use of non-linear indicators allowed us to obtain 100% classification accuracy with a small number of samples. • The article discusses the detection and identification of cylinder misfire in small aircraft engines in different operating conditions. • The detection is based on the linear and non-linear properties of vibrational signals. • The complexity and path of diagnostic signals require finding changes in frequency components. • The location of sensors does not affect the monitoring of the engine's operating status. • Machine learning classified each of the damaged cylinder, and the use of non-linear statistics increased the accuracy by 23% with 100% classification. [ABSTRACT FROM AUTHOR]

Abstract: The cost of maintaining aeroplanes is still considerable. It concerns especially operation cost where fuel is a substantial part. At the moment the special 100LL gasoline is used to fuel aircraft piston engines. It is about 20% more expensive than ES95 gasoline featuring comparable properties. The article shows the results of test-bed research conducted on the radial piston aircraft engine fuelled by aircraft 100LL gasoline and automotive ES95 gasoline. The object of research was ASz-62IR engine by WSK PZL-Kalisz that was equipped with an experimental fuel injection system. Power, fuel consumption, head temperatures and indicated pressure in cylinders were analysed in the selected typical operating points. The testing was carried out in steady state. It was proved that it is possible to exchange fuels with no engine power loss and merely an insignificant increase of fuel consumption but with significant increase of IMEP cycle-to-cycle variation. [ABSTRACT FROM AUTHOR]

Abstract: The paper presents an algorithm of idle speed stabilization in the spark ignition automotive engine by means of spark advance control. The algorithm is based on a well-known approach of a model-based adaptive control and uses artificial neural networks. The control algorithm is based on a neural network model observer of the additional effective torque. The additional load is estimated as difference between effective torque, estimated by the neural network observer, and brake torque, estimated on the basis of a linear quadratic model. In that case the additional load is understood as the sum of the alternator brake torque (additional load form electric car equipments) and the momentary and/or permanent changes of the engine’s characteristics. On the basis of estimated values of the additional load, the required value of angular acceleration is determined to make the engine return to the specified speed. This acceleration is achieved by adjusting the spark advance. The required value of spark advance is estimated by means of a neural network model converse to that of the effective torque. The algorithm was experimentally compared with PID and adaptive algorithms in the same test bed. The tests were conducted under sudden change of external load. The proposed algorithm proved to be more effective in terms of control error. [Copyright &y& Elsevier]

• Aircraft engine cylinder misfire. • Frequency analysis of the experimental signals. • Recurrence analysis of the experimental signals. • Nonlinear effects in the engine dynamics. The aim of research was to detect the misfire of individual cylinders of the Rotax 912 ULS aircraft engine based on engine vibration signals. Vibrations were recorded in three direction, and their time series subject to linear frequency analysis and non-linear recurrence analysis. The greatest vibration difference between a fully operational engine and the engine with one piston off was observed along the piston movement axis (Y-axis). With one cylinder off, the dynamic response of the engine changed in both linear and non-linear manner. Based on the spectral value of the power amplitude of two selected frequencies, a linear indicator describing the vibration level was developed. The values of non-linear indicators were calculated on the basis of the periodicity of the engine operation. Both methods proved capable of qualitatively detecting the fact of misfires in various cylinder configurations. Used in combination, they enable user to identify the defective cylinder. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]