AS A MEANS OF REDUCING THE LEVEL OF EXTERNAL NOISE CHASSIS KRAZ-6511NE

Abstract

Ukraine’s full-scale war with its northern neighbor has been going on more than two years now. One of the most important laws of war is: “If you don’t detect it, you don’t hit the target.” It’s about masking. In wartime, the camouflage properties of a military vehicle are especially relevant. There are a number of ways to improve them. One of them is reducing the external noise level of a military vehicle. Using the example of the KrAZ-6511NE chassis, one of the ways to reduce noise is considered. The BM 9P140 “Uragan” antiircraft missile system is placed on this chassis. The developed silencer has the ability to change its frequency response synchronously with the change in the engine crankshaft rotation frequency. The developed muffler is a well-known twochamber reactive muffler, which is modified by the ability to change the effective lengths of the chambers. A diagram showing the operation of the developed noise muffler is given, where the main elements are: two muffler chambers, a connecting tube, piston drive mechanisms of the first and second muffler chambers, respectively, an electric motor, a control unit, and a sensor for determining the frequency of rotation of the crankshaft. The acoustic efficiency of this muffler was determined with fixed geometric parameters (outer diameter, diameters of the inlet and outlet pipes) and variable effective lengths of both chambers, families of frequency characteristics were constructed for various combinations of the muffler’s geometric parameters. To construct graphs, code was written in Python, which uses the NumPy and Matplotlib libraries. As a result of the introduction of the developed noise muffler, it is predicted that the external noise level of the KrAZ 6511НЕ chassis will decrease by 5-7 dBA in the speed range of 45-85 km/h.