A Study on Internal Flow Field of Military Protective Mask

• Main Authors: Chuang, Chih-Yuan, 莊致遠
• Other Authors: Li, Chun-Chi
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/84115427720902879596

碩士 === 國防大學理工學院 === 機械工程碩士班 === 100 === In this paper, computational fluid dynamics (CFD) method is used to simulate a global flow field in the military protective mask and to explore aerodynamic characteristics of the flow field inside the military respirator. Identify the impact factors that influence the internal flow field in the overall pressure drop and flow structure of the masks. As the reference of configuration improvements and reach the lower respiratory piezoresistive enhance wearing comfort. The simulation of the entrance inlet flow is set to the conditions 15, 30, 80, 85, 110 and 135L/min. The governing equation is the three-dimensional steady state Reynolds average Navier-Stokes equation, and the low Reynolds number - turbulence mode is embedded in the governing equations for the average air age in order to determine the standard space dead zone and the air age. The results show that the most important parameter impacts the respirator's aerodynamical characteristics is the distribution and number of the inlet holes. In the Model D, the average flow of inlet air is 85L/min, the pressure drop in the nasal cavity is 176Pa, compared with the one of Model A, which is under the same inlet conditions, is 691Pa, 515Pa is reduced and the decline is up to 75%. The purpose of breathing comfort is achieved by the lower nasal respiratory pressure drop than the one designed with the jaw at a single inlet mask. On the other hand, study results of Model A and Model B show that in the same kind of respiratory conditions, the Model B with 97 canisters has the more maximum voltage drop value of the canister and the additional work of breathing than the Model A with 62A type. The decline is up to 40%. To take the safety of personnel into consideration, the 97 type of the canister can be replaced the 62A-type canisters serving in the military right now.