3D Pump Impeller Design
The meridional shape, number of blades and component specific work rVt (ie. impeller head) were loaded from TURBOdesign Pre into TURBOdesign1 for the detailed 3D design of the pump impeller. TURBOdesign1 is a unique blade design software that uses the 3D Inverse Design approach to compute the blade shape for a given blade loading distribution.
It is well known that the main source of hydrodynamic loss in medium specific speed centrifugal pump impellers is the formation of secondary flows in the impeller, so ADT engineers started the impeller design with a spanwise loading distribution known to systematically suppress secondary flows. Such blade loading, represented in Fig. 1, features an aft-loaded hub that increases surface velocities on suction surface of hub and a fore-loaded shroud that removes surface velocities on suction surface of shroud. This spanwise loading distribution results in net reduction of reduced static pressure gradients on suction surface and hence suppresses secondary flows resulting in high impeller efficiency and the more uniform exit flow ensures very good stage efficiency.
A number of design iterations were performed directly in TURBOdesign1 with the help of the 3D inviscid flow solution and performance data provided by the code to fine tune the meridional shape and blade loading, before assessing the impeller performance via 3D CFD. The initial design loop in TURBOdesign1 taking less than 30 seconds per design iteration, it ensures large areas of the design space are covered with minimal number of CFD iterations, making it possible to achieve breakthrough designs without increasing product development costs.
3D Turbine Impeller Design
The turbine impeller was also designed in TURBOdesign1 following a similar process and principles as the pump impeller design, the aim being to achieve high total-to-static efficiency by reducing the accumulation of low momentum flows and exit swirl at the impeller trailing edge. To achieve this target the initial turbine impeller was designed with a fore-loaded hub and mid to aft-loaded shroud as presented in Fig. 2.
A design system based on TURBOdesign1 facilitates development and transfer of design know-how across designers, projects and teams, resulting in improved engineering productivity and company’s industry competitiveness. These unique advantages are only possible thanks to the 3D Inverse Design approach implemented within TURBOdesign1 as it ensures the design inputs are based on aerodynamic / hydrodynamic design parameters instead of geometrical blade angles.