Investigations for air flow turbulences are quite important to clarify small-particle contamination mechanisms in clean chambers. Strongly fluctuated air flow turbulence is recognized behind pleated air filters. Turbulent flow characteristics behind pleated high-efficiency particulated air filters are numerically analyzed and studied by direct simulation using a 3rd-order Kawamura-Kuwahara scheme. As the result of the study, the following typical phenomena were found: (1) Free shear caused by flow velocity nonuniformity makes vortex streets behind the filter ends. These vortex streets interfare with neighboring streets and spanwise synchronized fluctuation is generated. (2) Streamwise distribution of <u′2> has a sharp peak with some distance from the filter ends. This peak appears at the position the vortex interference starts. Rate of the mean velocity change becomes maximum in this position. (3)Results calculated by direct simulation are qualitatively in good agreement with the experimental results.
|ジャーナル||Transactions of the Japan Society of Mechanical Engineers Series B|
|出版ステータス||Published - 1992|
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