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目的 第1報で巻糸体周りの流れ状態の実験的な測定及び観察を行い, 第2報でこの流れを有限要素法により理論的に求めて考察した結果, 実験値と比較してほぼ一致した.そこで本報では, 第1報の実験手法並びに第2報の解析法を用いて, 巻糸体周りに種々の形状のカバーを設置して, カバーが巻糸体の動力損失に及ぼす効果を考察し検討する.成果 本研究によって得られた結果を以下に示す.1) カバー設置による巻糸体の動力損失に影響を与える因子として, 前報に記したポンプ作用による因子と巻糸体とカバー間のせん断力による因子の他に, 巻糸体とカバー間内で流体が巻糸体に衝突することによる抵抗による因子があり, 円筒カバーはこの影響が大きいことが分かった.2) 円筒カバー設置により巻糸体周りの流体の撹拌領域が減り, 動力損失は小さくなった.そして, このカバー高さは大きいほど動力損失は小さくなった.しかし, カバー高さが巻糸体周りの流れの吹き出し幅よりも小さいとこれが吹き出し流れの障害となるので, 動力損失はカバーなしのときよりも大きくなった.3) カバーに角度をつけた場合, その傾きが巻糸体テーパ部のそれと同じ角度のとき, 動力的に他の本研究で試みたすべてカバーも含めて最もよいことが分かった. We performed some experimental tests and observations of the flow around the high speed rotating pirn in the first report, and we theoretically obtained this flow by using the FEM in the second report. The results showed that the theoretical values gave approximation to the experimental values. In this report; we analyzed the effects of the various cover shapes on power loss to rotate the pirn.The results obtained are as follows : 1) In the two previous reports, we supposed two factors to produce the power loss, caused by the air pump effect and the shearing force between the rotating pirn and the cover. In this report, we considered another factor that the air flow inside of the cover collides with the surface of the rotating pirn. Especially in case of cylindrical covers, this effect is remarkable.2) It is shown that the space in which the rotating pirn stirs the air around itself, is reduced by setting the covers and the effect generally makes the power loss decrease. The higher the cover becomes, the more the power loss decreases. On the contrary, when the height of the cover is smaller than that of the region in which the air blowes out from the rotating pirn, the power loss is larger than that without the cover because it prevents the flow from blowing out.3) The cover, of which the cross sectional shape is triangle and the base angles are 20 degree the same as the taper angle of the pirn, is most effective to reduce the power of all covers tested in this study

The flow around the rotating pirn and power loss. Part 3. Effects of the cover shapes on power loss to rotate the pirn.