Flowfield Simulation and Analysis inside a CPAP Full Face Mask

• Main Authors: HUNG-SHIAU CHEN, 陳泓孝
• Other Authors: Sheam-Chyun Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/462gf2

碩士 === 國立臺灣科技大學 === 機械工程系 === 99 === Because of the narrow upper respiratory tract, patients with Obstructive Sleep Apnea Syndrome (OSAS) symptom may stop breathing momentarily during sleep and frequently downgrade their life quality seriously. Previous investigations have demonstrated that Continuous Positive Airway Pressure (CPAP) is the most efficient alternative for OSAS treatment via delivering the compressed air stream through trachea. However, to achieve the optimal effect, a well designed full-face mask is required in conjunction with the CPAP device. Therefore, designing a well full-face mask is an essential and challenging task for the OSAS treatment and become the goal of this study. At first, a sophisticated CFD code Fluent is selected in utilizing LES scheme to simulate the flow pattern inside the mask. With the aids of flow visualization, the adverse circulation phenomenon and the CO2 distribution are identified for finding out the possible improvement strategies. Accordingly, the proposed modifications include adding the guiding plate, increasing the bending radius of intake tube, and changing the number, location, and total area of ventilating holes. As a result, the CFD calculations indicate that the redesigns of intake tube and guiding plate can eliminate the reversed circulations. Also, these new ventilating holes induce the decrease of CO2 distribution inside the mask. Overall speaking, the new designed mask is much superior to the original design by reducing 68.7% of CO2 distribution. In summary, this research successfully establishes a rigorous and effective scheme for serving as an important R&D tool to design the high-performance full face mask.