在相似模型Ⅰ的基础上，收缩管的直线圆锥改造成母线为圆弧形的圆锥，称相似模型Ⅱ。
On the base of resemble model ⅰ, the figure of contracting pipe was changed , the generatrix became arc for once it was straight line , named resemble model ⅱ .
圆锥母线