An investigation of asymmetric flow features in a scaled-up driven model of the human vocal folds |
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Authors: | Byron D Erath Michael W Plesniak |
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Institution: | (1) Purdue University, School of Mechanical Engineering, West Lafayette, IN 47907, USA;(2) Department of Mechanical and Aerospace Engineering, The George Washington University, Washington, DC 20052, USA; |
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Abstract: | Flow through a driven, 7.5 times life-size vocal fold model was investigated at corresponding life-size flow rates of Q
mean
= 89.1 ml/s, 159.4 ml/s, and 253.0 ml/s. The flow was scaled to match physiological values for Reynolds, Strouhal, and Euler
numbers. The models were driven at a life-size frequency of 94 Hz. Particle image velocimetry (PIV) data were acquired in
the anterior–posterior midplane of the glottis, and the unsteady transglottal pressure drop across the vocal folds was simultaneously
measured. Flow and pressure data were obtained at four discrete instances during the closing phases of the phonatory cycle
for which t/T
open
= 0.60, 0.70, 0.80, and 0.90. The glottal jet trajectory exhibited a bimodal distribution of flow attachment between the
two medial surfaces of the glottis. Vortex shedding at the trailing edge separation point generated instabilities in the shear
layer, which caused large oscillations in the glottal jet orientation downstream of the glottal exit. The development of the
Coanda effect during the glottal cycle was found to have minimal impact on the transglottal pressure drop, suggesting that
flow orientation does not directly influence the dipole sound source. The change in transglottal pressure drop as a result
of jet trajectory was less than 2% for all three investigated flow rates. |
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Keywords: | |
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