| 引用本文: | 田章福,赵云,龚昌超,等.超声速调制气流声源声压级增益特性的理论与实验.[J].国防科技大学学报,2014,36(4):158-162.[点击复制] |
| TIAN Zhangfu,ZHAO Yun,GONG Changchao,et al.Research on the performance of a supersonic flow modulated speaker[J].Journal of National University of Defense Technology,2014,36(4):158-162[点击复制] |
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| 超声速调制气流声源声压级增益特性的理论与实验 |
| 田章福, 赵云, 龚昌超, 孙海洋 |
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(国防科技大学 光电科学与工程学院，湖南 长沙 410073)
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| 摘要: |
| 通常认为，当气室压力提高到一定程度，调制气流声源声压级输出将趋于饱和。为了从基本原理上探讨进一步提高声源输出的途径，设计了收缩-扩张喷口，将调制作用上游的声速流动提高至超声速。理论分析表明，来流气压较高时，超声速调制优于声速调制，可获得一定的声压级增益。增益量随喷口面积比减小而增加。旋笛实验在调制频率较低时得到了超声速调制的声压级增益；调制频率较高时，受瞬态作用的影响，参与调制的气流很可能未完全发展为超声速流动，超声速调制与声速调制的旋笛性能相同。 |
| 关键词: 调制气流声源 超声速 声压级增益 |
| DOI：10.11887/j.cn.201404027 |
| 投稿日期：2014-03-20 |
| 基金项目:上海航天科技创新基金项目（SAST201314） |
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| Research on the performance of a supersonic flow modulated speaker |
| TIAN Zhangfu, ZHAO Yun, GONG Changchao, SUN Haiyang |
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(College of Optical-electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China)
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| Abstract: |
| It is generally acknowledged that the sound pressure level (SPL) of air-modulated speaker (AMS) will finally reach the level of saturation when the chamber pressure increases to a certain degree. As a new approach to obtain higher SPL output, supersonic flow modulation was discussed in which the flow speed of nozzle exit was increased from sonic to supersonic. Results from the quasi-steady theory proved that, when the chamber pressure is high, the SPL in the supersonic case is higher than that in the sonic case. Larger SPL increments generally appear at smaller nozzle area ratio. The improvement of the source intensity was validated by the comparison of sound measurements between the sonic and supersonic cases in low frequency modulation. But in high frequency modulation, due to the transient flow effect, the SPL in the supersonic case is the same as that in the sonic case while the air jet is considered to be not fully developed or sped up to be supersonic. |
| Keywords: air-modulated speaker supersonic sound pressure level increment |
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