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本文介绍了声学聚焦镜在整车风洞内汽车车外风噪声测量中的应用。声学聚焦镜能以较高的精度测量不同风速下的车外噪声分布 ,辩识主要噪声源区。本文还介绍了风洞内气流对声学聚焦镜空间分辨率及增益的影响。 相似文献
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噪声源识别对噪声控制具有重要意义。在建立多输入/单输出系统噪声模型,分析介绍噪声源贡献量测量及偏相干分析技术的基础上,给出偏相干函数的条件谱计算公式。针对0.55 m×0.4 m航空声学风洞,拟定噪声测试方案。结合噪声测试数据,表明风洞主要噪声源识别的有效性。 相似文献
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在构建的汽车水泵总成半消声室噪声测试系统中,针对汽车水泵的工作噪声特性,确立了企业水泵总成噪声测试规范,用于评价汽车水泵总成件的噪声性能。测试表明:正常水泵工作噪声声压谱在400 Hz~10 kHz范围内呈现高低两个单频峰值结构噪声源,高转速下水泵主要噪声源为宽频涡流噪声。转速和防冻液温度对工作噪声影响较大,低速、高温工况下的工作噪声应为水泵噪声主要质量控制点。水泵工作噪声合格性评判除包括稳态工作转速下测量表面总声功率和声功率谱外,还需控制其提速过程中的总声功率,以防止结构共振噪声。 相似文献
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针对某轿车车内异常噪声现象,通过道路试验进行了噪声源识别,发现发动机的进气系统是异常噪声的主要来源.因此,采用共振消声的原理,设计了合适的共振腔,降低了低频噪声成分,并采用阻尼降噪技术,对空气滤清气的支架进行了处理,降低了高频噪声成分.从而使车内的异常噪声得到了有效的控制,声音质量得到了显著改善. 相似文献
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由于风洞阻塞率的限制和室外平台上测点的布置要求,某千米级摩天大楼的风环境试验只能采用节段模型,因此如何将试验数据用于实际大楼室外平台的行人风环境评估是一个需要解决的关键问题。为解决这一问题,该文在对CFD数值模拟方法的可行性进行验证的基础上,采用该方法研究了摩天大楼整体模型与节段模型的行人风环境特性,比较了不同挡风板措施的影响;利用统计学中的四分位法确定了整体模型的最不利风环境平台为平台4;最后,将整体模型平台4与节段模型平台2的CFD结果进行比较,确定了由节段模型向整体模型转换的风速调整系数,从而建立了由节段模型风环境试验数据向实际大楼行人高度风速转换的纽带,为后续的行人“风舒适性”与“风安全性”评估奠定基础。 相似文献
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研究借助气动-声学风洞试验平台,首先针对某高速列车的1:8缩尺比例的三车编组模型建立了气动噪声试验方法和突显不同的噪声源的模型处理方法,并结合流场外自由场传声器和传声器阵列的测量结果,分析了模型上的主要噪声源特性及对整个模型的贡献量大小。研究表明:转向架和受电弓噪声是模型的最主要噪声源,其次是车连接部位间隙,再次是鼻尖和排障器,最后是尾车,同时,并给出了这些噪声源的特性,这对于认识高速列车气动噪声和改善设计有重要的参考价值。研究也说明所提出的试验研究方法是一种研究高速列车气动噪声较为有效地方法。 相似文献
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国内外对燃料电池轿车总体噪声的研究中已指出,空气辅助系统是燃料电池整车的主要噪声源;在对此的分析和介绍中,通过一个实例给出了某燃料电池车空辅系统噪声频谱特性;最后总结了燃料电池车空辅系统噪声研究的方向。 相似文献
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本文在对几类小波基的降噪效果进行分析的基础上,确定了一种小波降噪方案,将其应用到典型大跨与高层结构风洞试验同步测压信号的预处理,分析了仪器噪声对极值风压、风致位移和加速度响应计算结果的影响。结果表明:symN小波为风压信号预处理的最优小波基,通过调整其消失矩阶数可以分别获得不同信噪比信号的最佳降噪效果。对于一体育场屋盖,仪器噪声对最大峰值负压估计的影响较小,但会不同程度地高估大跨度屋盖结构的位移响应,仪器噪声会使得位移的共振和背景分量分别被高估7.69%和70.6%,并最终使总响应被高估16.96%。对于某439m高的超高层建筑结构,较长重现期风速作用下结构风致响应的计算受仪器噪声影响相对较小;但对于较短重现期风速来说,噪声对建筑顶部峰值加速度响应估算的影响依然不容忽视,采用有效的减噪措施可以提高风致峰值加速度的估算精度。 相似文献
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Injuries to unrestrained occupants in small car-small car and large car-large car head-on collisions
Loren A. Zaremba 《Accident; analysis and prevention》1980,12(1):11-29
Estimates were made of the effects of observed differences in the crash responses of small and large cars on the likelihood of injury to unrestrained occupants in small car-small car and large car-large car head-on collisions using a simple spring-mass model. Two measures of the likelihood of injury were computed: the relative velocity of an unrestrained occupant and car at the instant the occupant strikes the interior, and the approximate closing speed at which occupant compartment intrusion would be expected to begin. Model estimates of the intrusion thresholds for large ear-large car and small car-small car head-on crashes were comparable. However, unrestrained occupants were predicted to strike the interiors of their cars at a lower relative velocity in a head-on crash involving two large cars than in a similar crash involving two small cars. Head-on crashes involving a large and small car were also modelled for purposes of comparison. The estimated intrusion thresholds for small cars in such crashes were considerably lower than in small car-small car crashes. Also, calculations indicated that in a small car-large car head-on crash, an unrestrained small car occupant strikes the interior of his car with a higher relative velocity than an unrestrained large car occupant, and this velocity is higher than if his car struck another small car. However, the difference in the relative velocities with which unrestrained small and large car occupants impact the interiors of their cars in small car-large car collisions was found to diminish with increasing closing speed. These results suggest that the frontal structures of small cars should be longer and less stiff than on current models and the occupant compartment should be stiffer. Such designs would help to reduce injuries to restrained and unrestrained small car occupants in collisions with both small and large cars. 相似文献