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为了减少与航天飞机有效载荷舱声环境有关的不确定因素,进行了两系列试验。利用1/5缩比模型所做的试验表明,在放入典型有效载荷时,频率低于125赫的声级发生较大的变化。这些变化与特殊的声模态特性有关,且对声激励类型敏感。另一系列试验对第一个轨道飞行器(OV-101)的噪声降低做了评价。结果表明,掠入射激励时的噪声降低始终比扩散激励时的大。利用质量定律关系和加速度测量方法将结果外推至 OV-102。
In order to reduce the uncertainties associated with the spacecraft payload aeronautical environment, two series of tests were conducted. Experiments with the 1/5 reduction model show that there is a large change in the sound level below 125 Hz when a typical payload is placed. These changes are related to the specific acoustic modalities and are sensitive to the types of acoustic stimuli. Another series of tests evaluated the noise reduction of the first orbital aircraft (OV-101). The results show that the grazing incident excitation noise reduction is always greater than the proliferation of excitation. Extrapolate the results to the OV-102 using the mass-law relationship and the acceleration measurement method.