Optimal Fan Design with 3D Inverse Design

DOWNLOAD PDF

Introduction

Meridonial grid used for TURBOdesign1ebm-papst Mulfingen was founded in 1963 by Gerhard Sturm, still actively heading the company, and Heinz Ziehl. Everything started with the external-rotor motor which was rediscovered then as an ideal drive for small fans. As the pillar and basic principle of our innovative and wide product range, the external-rotor motor made Ebm the world market leader. In the 1970s, both Ebm and Papst were innovators in the field of brushless EC drives. This guaranteed them an important edge in terms of know-how that they have been able to maintain right up to the present day. In 1992, Ebm took over PAPST Motoren GmbH & Co. KG, following this up in 1997 by acquiring MVL Motoren Ventilatoren Landshut GmbH. The Ebm, Papst and MVL companies took the joint brand name Ebm-papst in 2003.

Today, with approximately 10,000 people in 57 subsidiaries and 17 production facilities worldwide, ebm-papst produces high quality fans and motors for many markets such as heating and air-conditioning, ventilation, refrigeration, automotive, IT/telecom and drive technology. The turnover of the whole group was 1,076 million in the fiscal year 07/08. The ebm-papst product portfolio comprises about 14500 different items and the global production in 2007/08 was 55.6 million fans and motors.

“TURBOdesign1 shaped out to be the most suitable tool for developing new fan blades, promising gain of time and better understanding of the aerodynamics”

Design Process

The direct approach for designing a new impeller requires a lot of geometrical parameters. In addition, the correlation between geometrical parameters and aerodynamics is unknown in most cases. Therefore, a lot of CFD calculations or measurements have to be done until the best configuration is reached.

 

Comparison of shroud blade pressure predicted by TURBOdesign1 and calculated with CFD with simplified meridional channel

 

“Searching for new tools to make the design process faster and more efficient, an extensive benchmark of available design tools was carried out at Ebm-papst.”

Advantage of TURBOdesign1

Searching for new tools to make the design process faster and more efficient, an extensive benchmark of available design tools was carried out at ebm-papst. TURBOdesign1 shaped out to be the most suitable tool for developing new fan blades, promising gain of time and a better understanding of the aerodynamics.

With TURBOdesign1, only a few geometrical parameters are needed. The main input is the blade loading, which directly controls the aerodynamic flow field. In particular, TURBOdesign1’s prediction results are very accurate as well as controlling the potential flow field. Figure 2 shows the comparison of the shroud pressure distribution, predicted by TURBOdesign1 and verified with CFD, for a backward curved radial impeller with a diameter of 450 mm. In order to have a fair comparison, CFD analyses were carried out with a simplified meridional channel (see Fig. 1), which is identical to the one used in the design with TURBOdesign1 (no gap between stationary and rotating parts).

Even when considering the actual meridional channel in CFD analyses, as the one reported in Fig. 3, the TURBOdesign1 prediction of the potential flow field is in good agreement with CFD results, as shown in Fig. 4.

Meridonial geometry used for FLUENT™ calculation

 

The direct control of the potential flow field allows designers to control all the main sources of losses, like the secondary flows and the tip clearance flow, that affect axial and centrifugal fans.

Hence many different designs can be analysed and evaluated without time-consuming CFD calculation. Additionally, the results of a new design can give useful indications as to which parameters are important for the aerodynamics and if the desired pressure rise can be realised. Through easy and fast variation of input parameters, an optimal configuration can be found within minutes.

Conclusion

TURBOdesign1 can be a valuable tool in designing fans. It’s geometrical parameters are reasonable in realising the usual design specifications, with blade loading being an important parameter for aerodynamic and aeroacoustic optimisation.

 

 Static pressure (Pa) distribution on suction side;  left: TURBOdesign1, right: FLUENT™ result with actual meridonial channel

 

Get the Latest Updates Direct to Your Inbox