Since the early 1970ies, when rotary lobe pumps were invented mostly for agricultural purposes, application areas have spread from fertiliser distribution in farming to disposal and wastewater management in civil engineering and general industry. Rotary lobe pumps are the most reliable pumps in farming but like any other technical equipment need to be optimised and re-designed steadily to keep up on the market.
Traditionally, pump development involves intensive physical testing but modern engineering offers much more; for example computational fluid dynamics (CFD). Lead engineer Steffen Knabe from Hugo Vogelsang Maschinenbau GmbH, one of Germanys top leading rotary lobe pump manufacturers, uses TwinMesh for his CFD analysis to improve performance, durability, and life time for their rotary lobe pumps.
Thanks to modern engineering, meaning using state of the art virtual product development tools, the newly designed IQ152 series weighs less, consumes less power, and has a higher efficiency compared to its previous models. Find out more about what Steffen Knabe has to tell about his daily engineering life and what tools he uses to make engineering easier.
Finite Element Method (FEM) is a well-established engineering tool in the early development phases of rotary lobe pumps at Hugo Vogelsang. However, CFD mainly have been used to optimise inlet and outlet ports of their complex pumps – until now. Due to the excessive man hours needed to ensure high quality CFD results, engineers are often only left to use reduced models with poor mesh quality to represent their machines.
Thanks to CFX Berlin’s meshing tool TwinMesh positive displacement (PD) machine engineers now have a tool to analyse and optimise their whole machines without compromises. Steffen Knabe points out that especially axial and radial gaps cannot be neglected in CFD analyses and have a severe impact on machine performance prediction. Also, using structured grids and a reasonable time resolution during the simulation is essential. Therefore, Steffen Knabe believes that TwinMesh as a tool itself is the foundation for a solid, reliable, and accurate simulation and in his case for rotary lobe pump development and optimisation.
For the newly developed IQ152 series Hugo Vogelsang performed excessive physical experiments in order to validate their CFD results. In fact, during those experiments the influence of the revolution speed on the torque was investigated and almost perfectly matched the simulation data.
In addition, the experimental data showed that changing the revolution speed also impacts leakage flows, which could be confirmed by post processing the simulation data. The figure to the left shows streamlines in the inlet area of the new IQ152. The simulation data revealed dead zones in that area as well as secondary vortices leading to a reduced coefficient of performance (CoP), higher energy consumption, and negative influence on cavitation behaviour.
Consequently, Steffen Knabe and his colleagues found an inlet design to eliminate those dead zones and unwanted vortices (see figure on the right). Another benefit of the new design was material reduction of the cast housing leading to less pump weight and lower production costs of the new rotary lobe pump series. Moreover, due to the straightforward TwinMesh and CFD setup is was possible to easily vary the rotor design thus finding a rotor design with low cavitation behaviour.
Altogether, the new design leads to an extended pump life thus reducing maintenance time and frequency to the benefits of Hugo Vogelsang’s happy customer. In conclusion, Steffen Knabe is happy to recommend TwinMesh to any PD machine manufacturer and definitely will use CFD and TwinMesh for the development of Hugo Vogelsang’s next rotary lobe pumps.
You do not use CFD for your product development yet? – Well then it is time for you to get in touch with us.