The National Transport University Bulletin

Abstract

The article proposes the use of the active noise cancellation method to reduce the internal noise level of a military vehicle. The object of the study is the specialized armored vehicle «Novator» (SAV «Novator»), which was created for rapid response units and can be used as a military reconnaissance vehicle. The purpose of the study is to reduce the internal noise level of a military reconnaissance vehicle through the use of an improved active noise cancellation system. The research method is computational. One of the components of any modern army are military vehicles that perform various functions, including command and staff or reconnaissance functions. Such military vehicles have high requirements regarding the level of internal noise, dictated not only by environmental considerations, but also by the need to ensure speech intelligibility and protection of speech information. This work examines the application of the active noise cancellation method for the «Novator» armored vehicle, the essence of which is to create an additional artificial controlled source of acoustic waves, precisely such waves, which, superimposed on the noise waves, will neutralize the latter in the necessary space. This is possible under condition that the artificially created acoustic waves are of the same frequency and amplitude as the «noise» acoustic waves, and in the necessary place of space – also in antiphase with the latter. Taking into account that the effectiveness of the active noise cancellation system can be significantly reduced at times when the frequency of rotation of the crankshaft of the engine changes sharply, if the active system does not have time to react to these changes, a decision was made to improve the latter. The essence of the improvement is to add a set of active resonator mufflers to the existing active noise cancellation system. Each of the resonator mufflers can change its resonance frequency. Their work is synchronized with the work of the vehicle's internal combustion engine. The number of single resonator mufflers is determined experimentally, based on the spectrum of the predicted internal noise. As a result of the introduction of the improved active noise cancellation system, it is predicted that the internal noise level of the «Novator» armored vehicle will decrease by 7–11 dBA in the speed range of 45–85 km/h.

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