AIAA-2005-565-450Acoustic Testing of the dielectric barrier(7)

推进器的声波特性

Figure 10: Filtered data showing the microphone waveform (40 degrees, 5 kHz and 8 kHz 5 kV) At both frequencies (5 KHz and 8 KHz) there are two positive peaks in the acoustic waveform, one being larger than the other, and two negative dips or valleys. Although similar, the difference in the acoustic waveform for the two different frequencies can be seen by examining the valleys of the waveform. For the 5 kHz case the first negative valley is nearly as large as the second but for the 8 kHz case the first negative valley is almost nonexistent and the second valley is much larger. Figure 11 and Figure 12 show the effect of the directional angle on the waveform for the two frequencies of 5 and 8 kHz, respectively. For the 5 kHz case the change in waveform with direction seems minimal. In the 8 kHz case the waveform changes with frequency with the first valley almost nonexistent at 40 degrees but rather large at 140 degrees. A possible cause of this is discussed in the next section.Figure 11: Microphone output waveform for different angles for 5 kHz at 5 kV.7 American Institute of Aeronautics and Astronautics