In January 2017 Systemair Germany started to integrate the NUMECA OMNIS™/Turbo CFD tool into their design chain and thereby replaced the existing competitive CFD software. This integration phase was supported by NUMECA Ingenieurbüro for one week to ensure a transition as smooth as possible. The training took place at Systemair site in Windischbuch/Germany on the example of a ducted axial fan with guide vanes, which is manufactured by Systemair in various sizes for many different kinds of applications.
The workflow started with a structured meshing approach with NUMECA’s OMNIS™/AutoGrid to achieve a high quality mesh with proper resolution of the boundary layer and the highest accuracy possible. Thanks to advanced features like meridional techno effects and a partial hub gap it is possible to model the complex geometry of the case with only little effort and in short time. Furthermore, the automatic bulb detection at inlet and outlet enables Systemair Germany to create a high quality mesh in regions where the cells would otherwise collapse at a radius of zero, too. Finally, OMNIS™/AutoGrid needs less than 5 minutes (on a single processor) to create the mesh containing 8 million cells.
Due to the low speed flow the fluid was assumed as incompressible air. The turbulence was modelled with the well-proven Spalart-Allmaras turbulence model. A mass flow rate at the inlet, an ambient static pressure at the outlet and the rotational speed defined the investigated operating point. The computation converged after just 4 hours (3 cores @ 3.4 GHz). Considering these facts with NUMECA’s software solutions dedicated to turbomachinery applications, Systemair Germany is able to perform their CFD calculations on an ordinary workstation PC.
During post processing with CFView™ the stator revealed potential for optimisation. As a next step, the influence of the tip gap size on the performance of the fan will be examined by the development engineers. Secondly, variations of the rotor and stator geometry are scheduled.
“Thanks to NUMECA our CFD workflow is accelerated drastically. Another great point is that we can mesh, solve and post-process with only one single license. And even unsteady computations are a practical possibility now because of the NLH method.”