Ejectors are simple fluid movers and mixers used in a range of industries; however, the attractiveness of their simplicity can be offset by high levels of noise generation. This work experimentally investigates the use of a silencer affixed to the outlet of a subsonic air–air ejector as a means of quieting the ejector. An emphasis is placed on finding a silencer design which has a minimal impact on the mass flow rate exhausting from the ejector (pumping performance). This paper discusses the results of 10 different silencer designs, tested in an attempt to further understand noise generation mechanisms and to find a practical method to reduce the noise of ejectors. It is found that the placement of a perforated cone at the mid-length of the silencer is the only solution tested which provides a significant acoustic advantage with only a small drop in pumping performance. Other solutions tested provide either no acoustic advantage or have too great of a reduction in pumping performance. It is found that the size and shape of the ejector can be designed in such a way to reduce the overlap of natural modes and thus the overall noise levels of the ejector caused by high levels of resonance. The use of acoustic foam to dampen acoustic natural modes proves that the natural modes of the ejector are a significant contributor to the overall noise levels.

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使用出口消音器使喷射器安静的实验研究

喷射器是用于一系列行业的简单流体推动器和混合器；然而，它们简单的吸引力可能会被高水平的噪音产生所抵消。这项工作通过实验研究了使用固定在亚音速空气-空气喷射器出口的消音器作为使喷射器安静的手段。重点放在寻找对从喷射器排出的质量流量（泵送性能）影响最小的消音器设计。本文讨论了 10 种不同消音器设计的结果，测试结果是为了进一步了解噪音产生机制并找到降低喷射器噪音的实用方法。发现在消音器的中间长度放置穿孔锥体是唯一经过测试的解决方案，它提供了显着的声学优势，而泵送性能只有很小的下降。其他经过测试的解决方案要么没有声学优势，要么在泵送性能上有很大的降低。发现喷射器的尺寸和形状可以以这样的方式设计以减少自然模式的重叠，从而减少由高水平共振引起的喷射器的整体噪声水平。使用声学泡沫来抑制声学自然模式证明喷射器的自然模式是整体噪音水平的重要贡献者。发现喷射器的尺寸和形状可以以这样的方式设计以减少自然模式的重叠，从而减少由高水平共振引起的喷射器的整体噪声水平。使用声学泡沫来抑制声学自然模式证明喷射器的自然模式是整体噪音水平的重要贡献者。发现喷射器的尺寸和形状可以以这样的方式设计以减少自然模式的重叠，从而减少由高水平共振引起的喷射器的整体噪声水平。使用声学泡沫来抑制声学自然模式证明喷射器的自然模式是整体噪音水平的重要贡献者。