民用飞机噪声适航审定中伪纯音影响的去除方法

在民用飞机噪声适航合格审中计算有效感觉噪声级时,通过引入纯音修正因子来考虑噪声频谱不规则性对人主观感觉的影响,但布置在地面上的传声器测量的噪声频谱中含有地面影响导致的伪纯音,使得纯音修正因子可能被高估,需要加以识别并去除。该文提出了一种识别和去除地面影响引入的伪纯音对纯音修正因子计算影响的飞行试验方法和分析方法。在适航噪声测量点旁布置倒置传声器,得到飞机直达噪声,可靠地识别实测适航噪声频谱中的伪纯音,基于"CCAR-36部"及其附件中方法的改进方法,去除伪纯音对纯音修正因子计算的影响。通过某型民机噪声适航审定飞行试验对该方法进行了验证,结果表明该方法满足"CCAR-36部"等规章要求,易于试验和分析实现,能准确去除由地面影响引入的伪纯音影响,提高了有效感觉噪声级的计算准确度。

Treatment of the influence induced by pseudo tone in civil airplane noise airworthiness

Tone correction factor is introduced to account for the influence of noise spectral irregularities on human subjective sensation when calculating the effective perceived noise level (EPNL) in civil airplane noise airworthiness certification. But the flight noise acquired by microphone mounted above ground contains pseudo tones induced by ground interference effect and the pseudo tones usually cause the tone correction factor to be overestimated. In order to identify and remove the influence of pseudo tones on tone correction factor, the flight test and data analysis method are presented. During flight tests an inverted-microphone device placed nearby reference noise measuring point is used to identify the pseudo tones precisely. On the basis of the treatment methods recommend by CCAR-36 and its annex, a new method of removing the influence of pseudo tones is presented. Then the flight test and data analysis method are verified by flyover noise tests of a certain civil airplane. The results show that the methods can identify and remove the influence of pseudo tones more precisely and conveniently and still meet the requirements of airworthiness regulations.