The shape of cross-section is an ellipse folded in half through one symmetry axis, and the axis keeps perpendicular with pinacoid-view.

断面形状为沿对对折的椭圆，此对终垂直于截面，其方向与平面上的中线无关。

The drawing method for the double channel impeller is studied.It is found that there is an in-conformity between the dimensions of plane-view and pinacoid-view of fluid cross-section.

摘要研究了污水泵叶轮常用的纸表达方法，发现平面上的断面投影结果与面中确定的断面形状尺寸不一致的问题。