CHARACTERISTICS OF GLOTTIS-INDUCED TURBULENCE IN OSCILLATORY FLOW - AN EMPIRICAL-INVESTIGATION

Turbulence inducement from the glottis was scrutinized by employing an idealized model of the larynx and trachea for oscillatory flow condit ions. The characterization of turbulence was achieved with the two-com ponent velocity measurements of split-film probe anemometry and with t he flow visualization of a smoke-wire technique. The apertures of two different (triangular and circular) shapes were utilized in the airway model to address the distinct effects of the triangular-shaped glotta l aperture on the generation development, and decay of turbulence. One of the salient turbulence characteristics for the triangular aperture case was found to be the relatively high turbulence levels around the center region (2r/D similar to 0) in conjunction with the asymmetric mean axial velocity across the frontal-rear (A-O-P) plane of the trach ea at one tracheal diameter (x/D = 1) downstream from the glottis. The detailed turbulence properties such as the Reynolds sheer stresses an d turbulence intensities for the triangular aperture case differed sig nificantly from those for the circular aperture case within a few trac heal diameters (x/D < 7) downstream from the apertures. The glottis-in duced turbulence was incipient during the acceleration phase of inspir ation and convected downstream with the traits of decaying turbulence.