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Assessment of vibration isolation generated by the inertial forces of an aircraft combustion engine on a test bench

Szymański Grzegorz M., Waligórski Marek, Misztal Wojciech

Diagnostyka

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2024

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Vol. 25, No. 3

art. no. 2024301

EN

The scientific issues that are the subject of this article are related to the assessment of the vibration damping efficiency of an aircraft engine installed on a test stand for the type of vibration isolator used. For this purpose, appropriate empirical tests were carried out on an aircraft internal combustion piston engine of the Rotax 912 type, under conditions of variable engine speed, for selected mounting locations of vibration transducers on the engine and its frame. The effectiveness of vibration isolation of vibrations generated by inertia forces was assessed, based on the proposed mathematical equations and the determination of the values of discrete impulse and energy measures describing them for accelerations, velocities and vibration displacements in various directions. Thanks to this, it became possible to perform a diagnostic assessment of the generation and propagation of vibrations and their isolation from the perspective of operational vibration loads on the object and its supporting structure, as well as in the context of the research reliability of the signal for a given type of damping of forces and moments of inertia.

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Influence of Dimethyl Ether Combustion in the Compression-Ignition Engine on the Peak and Effective Measures of the Vibroacoustic Process and Toxic Compounds Emission

Waligórski Marek, Bajerlein Maciej, Karpiuk Wojciech, Smolec Rafał

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 4

369--385

EN

The scientific paper conducted empirical studies related to the effectiveness of the use of dimethyl ether as an additive to diesel fuel and its impact on the efficiency of the mixture creation and combustion process. The measure of the above quality was the observation and parametric assessment of the then generated vibroacoustic processes, the relations of which were assessed using the peak and effective value of vibration accelerations, and also assessment of toxic exhaust gas components. The transformation of the main process into its vibroacoustic and emission representations allowed for the construction of mathematical relations between them, expressed in a specific engine operating space, and a vector of tribological parameters, expressing specific friction changes occurring in the critical kinematic pairs of the combustion and mixture formation area. The tests were carried out on a single-cylinder research engine with direct fuel injection, in stationary conditions with a time-invariant control vector. As part of the procedures, a constant and optimal value of thermodynamic parameters defining the thermal state of the engine was maintained, minimizing external forces and disturbances that could affect the active value of the measurement signal. The research results are empirical vibroacoustic and emission characteristics for various signal domains and their parameterization supplemented with a detailed analysis of the results, developed vibroacoustic and emission mathematical models depending on the operating parameters, type of fuel and combustible mixture formation variables, supplemented with an assessment of their degree of mapping to the dynamic source process. The dimethyl ether application resulted in a emission reduction by the coefficient: 24.3–57.8 (hydrocarbons), 1.03–1.24 (carbon monoxide), and an increase in nitrogen oxides in the range of 1.01–1.08. The use of dimethyl ether as a base fuel component has a positive effect on reducing the peak value of vibration accelerations in the range of 16–28%, and the root mean square in the range of 14–65%.

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Methodological basis of road acoustic researches

Batura Karolina Paula, Waligórski Marek

Combustion Engines

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2021

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R. 60, nr 2

32--38

EN

Transport is one of the most burdensome negative sources affecting the natural environment. Long-term exposure of the body to exhaust pollution can cause health problems and, in the worst case, even lead to death. In addition to exhaust emissions, traffic noise is another equally important issue. Due to its nature, variability over time or the design diversity of vehicles in the traffic flow, it is a phenomenon difficult to define. Like exhaust pollution, it affects people's health and quality of life. In addition to its direct impact on the human physical system, it can also cause psychosomatic disorders, which is why a detailed analysis of road noise taking into account the real operation of the vehicle is so important. The paper presents the basic concepts related to the problem of traffic noise in the world, determines the sources of noise in vehicles and the methodology of conducting acoustic road tests. At the final stage of the scientific paper, methods of reducing excessive noise levels in large urban agglomerations were also presented, and the effectiveness of using noise barriers on selected parts of the city road network using proprietary acoustic tests was assessed.