| Parameter | Definition |
| D1 | The entrance diameter, which is equal to 20 mm. |
| D2 | The throat diameter |
| D3 | The outlet diameter, which is equal to 20 mm. |
| d | Diameter of the suction port |
| di | The length of the intersection of the suction pipe and the throat on the symmetry plane. |
| α | Convergent angle |
| β | Diffuser angle |
| AB | The intersecting line of suction pipe and throat pipe on the symmetry plane. |
| CD | A line that is perpendicular to the midpoint of line AB. |