英语翻译中文四The background noises of the open jet wind tunnel wer

英语翻译中文四
The background noises of the open jet wind tunnel were rst measured in the absence of the airfoil at the jet speeds, vj of
33.3 m/s and 80 m/s. The airfoil, with rough sandpaper placed near the leading edge on both the pressure and suction sides to trip the boundary layer into becoming turbulent, was then attached to the
sidewalls and the measurement repeated at vj = 33.3 m/s. The
resulting narrowband noise spectra are plotted in Fig. 13b. Also
shown in the gure are the predictions of trailing edge self-noise spectra obtained from the empirical prediction scheme developed by Brooks et al. [6] as well as the background noise. The result sug- gests that, in the low frequency range between 100 Hz and 400 Hz, airfoil leading edge noise (triggered by the impingements of exit jet and the side plate turbulent boundary layers on the leading edge) and the side plate edge noise are the dominant noise sources. At higher frequencies, good agreement between the experiment re- sult and Brooks et al.’s prediction is observed over the frequency range of 0.5-6 kHz, thereby con rming that the measured noise is predominantly trailing edge self-noise in origin. In this measure- ment the broadband trailing edge noise is seen to be more than
15 dB above the background noise level at the peak frequency of
1 kHz and more than 10 dB at other frequencies.
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The background noises of the open jet wind tunnel were rst measured in the absence of the airfoil at the jet speeds,vj of 33.3 m/s and 80 m/s.开放式风洞的背景噪声在射流速度vj为33.3m/s和80m/s时,在不存在机翼的情况下进行了（rst）测量.The airfoil,with rough sandpaper placed near the leading edge on both the pressure and suction sides to trip the boundary layer into becoming turbulent,was then attached to the sidewalls and the measurement repeated at vj = 33.3 m/s.然后将机翼附于侧壁,在33.3 m/s的射流速度下重复进行测量,机翼在靠近前缘压力侧和吸入侧放上粗糙的砂纸,以使边界层跳脱（trip）成湍流的.The resulting narrowband noise spectra are plotted in Fig.13b.结果的窄带噪声谱示于图13b.Also shown in the gure are the predictions of trailing edge self-noise spectra obtained from the empirical prediction scheme developed by Brooks et al.[6] as well as the background noise.图中还示出了拖尾边缘的自噪声谱的预测值,它们来自于Brooks等人开发的经验预测方案【6】,以及示出了背景噪声.The result sug- gests that,in the low frequency range between 100 Hz and 400 Hz,airfoil leading edge noise (triggered by the impingements of exit jet and the side plate turbulent boundary layers on the leading edge) and the side plate edge noise are the dominant noise sources.结果表明,在100 Hz和400Hz之间的低频范围内,机翼前缘的噪声（因出口射流及侧板湍流边界层对前缘的冲击触发）,以及侧板的边缘噪声是处于主导地位的噪声源.At higher frequencies,good agreement between the experiment result and Brooks et al.’s prediction is observed over the frequency range of 0.5-6 kHz,thereby con rming that the measured noise is predominantly trailing edge self-noise in origin.在较高的频率下,在实验结果和Brooks等人的预测值之间,在0.5－6kHz频率范围内,一致性良好,因此证实了测得的噪声,起源主要是拖尾边缘的自噪声.In this measure- ment the broadband trailing edge noise is seen to be more than 15 dB above the background noise level at the peak frequency of 1 kHz and more than 10 dB at other frequencies.在这一测量中,在1kHz的峰值频率以上,看到宽带拖尾边缘噪声比背景噪声水平高15dB以上,而在其他频率下则超过10 dB以上.