An investigation of bimodal jet trajectory in flow through scaled models of the human vocal tract
An investigation of bimodal jet trajectory in flow through scaled models of the human vocal tract
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DOI：
10.1007/s00348-006-0106-0
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发表时间：
2006-05-01
影响因子：
2.4
通讯作者：
Plesniak, MW
中科院分区：
文献类型：
--
作者：
Erath, BD;Plesniak, MW
本文研究了通过静态发散模型的人体声带的二维脉动流。虽然这项研究的动机是语音生产，结果是普遍适用于各种工程流涉及脉动流通过扩散器。10度、20度和40度的模型声门发散角表示在一个发声周期中遇到的各种几何形状。流量振荡的频率和振幅与生理雷诺数和Strouhal数典型的人类发声缩放。通过使用相位平均粒子图像测速法沿前后中线沿着测量声门速度轨迹，以在发声周期中的10个离散实例处获得1,000个实现。声门射流从流向方向（对称配置）的角偏转量化为每个实现。一个双峰流配置观察到的发散角为10和20度，与流最终偏斜和附着到声带壁。当强迫函数达到最大速度和零加速度时，流向声带壁的偏转发生。对于40度的发散角，气流从未附着在声带壁上;然而，在强迫函数达到最大速度和零加速度后，声门射流的变异性增加。扩散器流态的性能图解释了作为发散角函数的射流轨迹的变化。小角度的情况下是在不稳定的过渡失速区，而40度发散的情况下是在充分发展的二维失速区。模型尺寸和表面光洁度的微小几何变化会显著影响流动行为。双峰，或翻转，声门射流行为预计会影响偶极子的声音产生的贡献。
Pulsatile two-dimensional flow through static divergent models of the human vocal folds is investigated. Although the motivation for this study is speech production, the results are generally applicable to a variety of engineering flows involving pulsatile flow through diffusers. Model glottal divergence angles of 10, 20, and 40 degrees represent various geometries encountered in one phonation cycle. Frequency and amplitude of the flow oscillations are scaled with physiological Reynolds and Strouhal numbers typical of human phonation. Glottal velocity trajectories are measured along the anterior-posterior midline by using phase-averaged particle image velocimetry to acquire 1,000 realizations at ten discrete instances in the phonation cycle. The angular deflection of the glottal jet from the streamwise direction (symmetric configuration) is quantified for each realization. A bimodal flow configuration is observed for divergence angles of 10 and 20 degrees, with the flow eventually skewing and attaching to the vocal fold walls. The deflection of the flow toward the vocal fold walls occurs when the forcing function reaches maximum velocity and zero acceleration. For a divergence angle of 40 degrees, the flow never attaches to the vocal fold walls; however, there is increased variability in the glottal jet after the forcing function reaches maximum velocity and zero acceleration. The variation in the jet trajectory as a function of divergence angle is explained by performance maps of diffuser flow regimes. The smaller angle cases are in the unstable transitory stall regime while the 40 degrees divergent case is in the fully developed two-dimensional stall regime. Very small geometric variations in model size and surface finish significantly affect the flow behavior. The bimodal, or flip-flopping, glottal jet behavior is expected to influence the dipole contribution to sound production.