Abstract: According to the limit to the application of the traditional pump CAD software, the impeller meridian streamline is to be fitted by using Bezier curve. The dispersed points on pump blade are obtained according to the meridian streamline, distribution of blade angle and differential equation of blade. An NURBS surface iteration method is introduced, and the surface can be adjusted by adjusting the reference points of the meridian streamline and the distribution of the blade angle. The relation between the numerical model of pump blade and the pump design parameters is built, so the clipping drawing of the pump impeller is unnecessary when designing the impeller, and the parameterized design of blade is achieved. The pump theory is further enriched. The example indicates that the numerical model of pump blade is rational, and it is of great value both in theory and in engineering practice.

Key words: CAD, Iteration, Numerical model of pump blade, NURBS surface