Article 5 #1'2024

© Volodymyr Fedorov, Ph.D., Associate Professor,
© Galyna Filipova, Ph.D., Professor,
(National Transport University)
© Oleh Kobzar, Ph.D., Associate Professor,
Jagiellonian University, Cracow, Poland
© Mykyta Malyshko, Master Degree,
(National Transport University)

Vacuum Muffler as a Means of Reducing the External Noise Level of The Kozak-7 Armored Car

Abstract. An important characteristic of military equipment is the level of camouflage properties. Among the methods of masking, an important role is played by reducing the external noise of military equipment. In this work, masking itself by reducing external noise will be considered. The Kozak-7 armored combat wheeled vehicle (hereinafter referred to as an armored car) was chosen as the object of the study. On the basis of the Kozak-7 armored car, a line of special vehicles can be developed: command and headquarters, control points, anti-tank complexes, medical, etc. This armored car, like most cars, has several main sources of noise, which together create its external noise. Exhaust gas noise is the most powerful component of external noise. Appropriate mufflers are used to reduce this type of noise. A highly efficient noise muffler, the so-called vacuum, has been developed, the principle of operation of which is to artificially create a vacuum with the help of a pumping unit directly in the muffler and in the inlet and outlet nozzles at the moment when the exhaust gases leave the engine, which makes it impossible for the latter to create acoustic noise. The dependence of the working time of the working cylinder of the muffler on the frequency of rotation of the engine crankshaft, the working volume of the engine, the volume of the working cylinder, the pressure and temperature in the engine intake manifold, the temperature of the exhaust gases, etc. This dependence will make it possible to determine the optimal parameters and limits of possibilities for the application of the described vacuum muffler system. Calculations made for an engine with a working volume of 5 liters show that at a rotation frequency of 2000-2500 min-1, the working time does not exceed ~ 0.05 s. This means, in turn, that the speed of the valves should be of the order of 0.01 s. Calculations of the efficiency of the pumping unit were made, which showed that for the efficient pumping of exhaust gases, and even more so to create sufficient vacuum in the exhaust system, the volume performance of the pumping unit must exceed the volume performance of the engine (for the case of theoretical one-hundred percent noise suppression of exhaust gases, which is not necessary in practice – at least several times). A forecast of the dependence of the external noise level of the Kozak-7 armored car on the speed of movement with the existing silencer and with the developed one was made.
Keywords: armored combat wheeled vehicle, armored car, “Kozak-7”, noise, camouflage, silencer, exhaust gases, engine, vacuum, timing diagram, pumping unit, cylinder.

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