Анализ частотного спектра шума подвесного лодочного мотора Hangkai 4.0 при капотировании

Abstract

The article deals with the results of experiments on measuring the Hangkai 4.0 outboard motor when using various types of noise-insulating hoods. The tests were carried out in accordance with GOST ISO 14509-1-2015 “Small Vessels. Noise measurement of small motor pleasure craft. Part 1. Noise of a passing ship” at full speed with the engine speed 4500 rev/min and motor power 4 HP. Measurements were carried out when the vessel was at a distance of 25 metres both sides with different options covering outboard motor. The average noise level and its frequency spectrum were measured, and the effectiveness of various types of hoods was evaluated. In the course of the experiment there was used a standard plastic hood of the Hangkai 4.0 engine, a noise-insulating hood (plastic hood, glued inside with automotive foil noise insulation) and an author's combined noise-insulating hood Kaponistr. Description and structural elements of Kaponistr are presented; it has been stated that the hood design was patented as a useful model in 2019. In the result of conducted experiments it has been inferred that the external noise level of the Hangkai 4.0 outboard motor (without hood) does not exceed 74.3 dBA, but is at the level of the permissible value of 75 dBA, so, when operating, the motor needs a standard hood. The prevailing frequency range of an outboard boat motor is within 300 - 2500 Hz. It has been inferred that each type of nosing (standard, sound-proof, combined, without hood) reduces the noise level of the outboard motor. The greatest effect of reducing external noise is observed when using a combined hood Kaponistr at a frequency of 800 Hz by 19.4 dBA or by 27%. In the research there were used the control and measuring devices (sound level meter, vibrometer, spectrum analyzer Ekofizika-110 (white); acoustic calibrator AK-1000) and software (Signal+3G Light manufactured by PKF Digital Instruments, LLC).