设计一种网柱形隔声罩,在普通实验室条件下,采用两种方法对发动机外特性曲线上的纯排气噪声进行试验研究.研究结果表明:实验装置可行;发动机纯排气噪声强度随转速升高而增大,中高频噪声比例也随之加大;发动机纯排气噪声与背景噪声是相干声波,根据相于声波叠加原理计算出的纯排气噪声与实验值较为吻合,验证两种测量发动机纯排气噪声方法的可行性.%A cylindrical acoustic enclosure is designed.Under common lab conditions, the pure exhaust noise in the engine' s outside characteristic curve is studied and tested with two methods.Results of testing indicate that the scheme and equipment of the experiment are right and feasible.Intensity of the pure exhaust noise increases when the engine to speed-up, and the noise in the middle and high frequency range also increases.The pure exhaust noise of the engine is coherent with background noise.The value of the pure exhaust noise determined by using superposition principle of coherent waves is in accordance with the experimental data.Thus, it is verified that the two methods for pure exhaust noise measuring of engines mentioned in this paper is feasible.
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