局所排気用二次元フードの形状が吸込流れ場に及ぼす影響

概要

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In the design of high performance local exhaust ventilation systems, it is of great importance to maintain the capture velocity as high as possible at a certain distance from the hood opening. To meet this demand, the effects of hood geometry on the suction performance were investigated experimentally in a two-dimensional flow field for the flare-and the flange-type hoods of various flare angle, hood length and flange width. In the far region from the opening, higher centerline velocity is achieved by the hood of large opening ratio both for the flare-type and the flange-type hood, regarding the outer edge of flange as flange opening width. In the near region, however, the reversed result is obtained for the flare-type hood, and the flange-type hood is superior than the flare-type one. On the nondimensional diagram, all the data of centerline velocities are distributed on a single curve, including the case of the flange-type hood, when the values (velocity and area) at the opening are adopted as normalizing parameters. This curve, however, deviates gradually from a hyperbolic curve proposed by Silverman and this is a reason that the suction performance is affected by the hood geometry. It is also shown from the study on the head loss at the hood inlet that there is an optimum flare angle of about 25°.
一般社団法人日本機械学会の論文
1991-05-25