Subtractive Rapid Prototyping for A Centrifugal Impeller Spacer: Design Manufacturing and Simulation Validation 2019-01-0506
This paper presents a method of rapid prototype manufacturing used in the development of a centrifugal pump impeller. In this research a rapid manufacturing technology was applied to create complex spacer profiles for testing as part of geometry optimization process for a high speed and high flow rate centrifugal pump impeller. Seven spacer designs relative to the standard radial impeller inlet configuration were simulated and evaluated with the use of computational fluid dynamics (CFD). One prototype design was selected for manufacturing and experimental testing for the purpose of results validation. The raw material was removed from a solid shaft by a cutting process under digital control from a computer file. A high volume of material layers, removed during the cutting operation, is wasted. The complexity of the modified impeller spacer profiles required the use of expensive CNC machining with five axis capability. This technique offers the possibility to produce components of increased complexity whilst ensuring quality, strength, performance and speed of manufacture. The ability to manufacture complex spacer profiles that are robust enough for testing, in a rapid and cost effective manner, is proved essential in the overall design optimization process for the specified pump impeller with six blades. The results validation aims to reduce uncertainty regarding spacer specifications as well as process properties that have not been anticipated.
The aim of the study was to use the virtual simulation processes to optimize the impeller’s spacer profile for the purpose of increasing the total efficiency of a pump, as CFD is a cost-effective method to obtain data. An overview of impeller blade performance, blade thickness, blade angle, manufacturing methods and required power consumption were analyzed. In this work the results from simulation modeling are compared to the experimental data. The experimental rig was a closed loop arrangement where a head tank contains water as the working fluid. The pump itself was driven by an induction motor to operate at a constant speed of 3600 rpm. The motor was connected to a dynamometer containing a load cell to accurately measure the input torque to the impeller for calculating the pump efficiency. The test procedure was to measure input power, suction pressure, and discharge pressure over a range of flow rates. Preliminary results demonstrated that adding the designed spacer at the impeller inlet has the potential to improve the pump efficiency.
Munther Hermez, Badih Jawad, Liping Liu, Mike Kheirallah
Lawrence Technological Univ, Advanced Safety & Energy Inc