建立了圆柱分支管y型三通的主管相贯线处的周长不变的条件，确定了相贯线为椭圆。

The invariablenes condition of circle girth of the join-line end of the main pipe was set up and the join-lines on Y-tee to be ellipse was made certain.

youdao

建立了圆柱分支管y型三通的主管相贯线处的周长不变的条件，确定了相贯线为椭圆。

The invariablenes condition of circle girth of the join-line end of the main pipe was set up and the join-lines on Y-tee to be ellipse was made certain.

youdao