Cutting Fan Design Time and Developing New Product Lines



FLEBU International in Norway, one of the leading fan and blower manufacturers in Northern Europe with major subsidiaries in Finland, Sweden and Estonia has been supplying to a global market since 1955. Primary market segments include maritime, offshore applications and increasingly demanding industrial and process applications worldwide. Their product line includes all layouts and combinations of centrifugal fans and blowers in a vast variety of materials from Black and Stainless Steel to Duplex and Hastelloy. FLEBU has remained at the forefront of its industry with a consistent dedication to always offering the best technical solution for each project with the concept of ‘tailor-made’ fans being their guide line. This long established aspiration has been consistently achieved by working in close cooperation with the customer in all phases of each project from initial design to final delivery. This strategy has resulted in achieving high success in all processes and activities from design and engineering to manufacturing.Single & dual stage combustion air fans

FLEBU has recently incorporated the use of TURBOdesign1 by Advanced Design Technology as a primary design tool to improve and enhance their increasingly growing product range. Historically FLEBU developed their fan designs with classical fan theories and a multitude of capacity tests which were carried out throughout the prior years of development. Although this approach produced designs with reliable performance and efficiency, it had always remained difficult to radically explore new designs, especially when attempting to integrate the acquired experience of existing fan theory with new younger design engineers to ensure a quick and highly productive turn around. In the past there was always a natural tendency to stick to well-known solutions but the advent of recent legislative changes to marine cabin noise and emission controls proved an opportunity to further investigate new tools.

Air fanThe decision to incorporate TURBOdesign1 followed an in depth evaluation of all available turbomachinery design software on the market. The choice fell on TURBOdesign1 for multiple reasons; a solid reference portfolio, ease of use and nonetheless very competitive pricing. “We have not been disappointed” says Erik Eriksson, Technical Manager at FLEBU, “although the FLEBU R&D team has only used TURBOdesign1 for 6 months we have already developed brand new designs for our increasingly growing market segments. The results have been truly amazing with extremely short lead times even though these were clean-sheet designs whereby we have already manufactured three prototypes and carried out thorough testing according to BS848, ISO 5801 and 3744.”

“Although the FLEBU R&D team has only used TURBOdesign1 for 6 months the results have been amazing and the lead time extremely short.”

Erik Eriksson, Technical Manager, FLEBU


Explosion-proof fansFLEBU has a 50% share of the world market for IG Fans which are an important component of Inert Gas Generator units installed on every oil tanker around the world. Their function is to insert Inert Gas and low oxygen content air into the tanks of the ship during unloading of the crude oil. Fans reliability is a primary concern as a malfunction can lead to catastrophic explosions. These types of blowers are therefore subject to very strict quality requirements where every unit is tested before delivery with a multitude of Class Tests, Capacity Tests and FATs.

Recent legislation changes impose a significant reduction in accepted maximum noise level on board of the ships, however noise insulation or acoustic enclosures are expensive solutions to the problem. “We want to attack the problem from the source” says Eriksson, “the idea is to reduce the noise generation of the fans by increasing efficiency and also changing their performance characteristics in order to closely match the best efficiency point to the actual duty point”. The ability of TURBOdesign1 to optimise the fan performance at a specific duty point is decisive. In the case of IG Fans this duty point is difficult to achieve being characterised by high pressure and very low flow for a fixed motor speed. “The solution obtained from TURBOdesign1 is completely new to us but optimizing the fan impeller design may reduce the noise generation by 5 to 6dB.”

"One unique strength of TURBOdesign1 is the ease by which you obtain a new optimized blade shape for each modification of the wheel design"

Erik Eriksson, Technical Manager, FLEBU

Return on Investment



In the case of IG Blower, Eriksson says “The solution obtained from TURBOdesign1 was completely new to us but optimising the fan impeller design may reduce the noise generation by 5 to 6dB.”


In this case the key aim was to reduce the fans diameter while maintaining performance. Eriksson says “The fan impeller diameter was reduced considerably without compromising performances and, very important, efficiency.”

FLEBU delivers ID fans with power of up to 3 MW to all major manufacturers of Exhaust Gas Cleaning System (EGCS). ID Fans are used to extract the exhaust gases from the boiler in modern power plants. The present legislation regarding emission control from these plants has considerably increased the requirement on the EGCS of which the ID Fan is a part of. To stay competitive, FLEBU has constantly been looking for new solutions to reduce costs and improve performance.


 Performance improvement with TURBOdesign existing design vs. new design


“In this case, we used TURBOdesign1 to solve two challenges” says Eriksson. “First we want to reduce the size, these fans can be of up to 3.5 meters in diameter and manufactured in expensive materials, therefore even a small reduction in impeller size can lead to a large reduction in manufacturing costs. We also want to slightly increase the rotation speed in order to make it possible to implement the use of motors with a lower number of poles that in turn reduces the total cost of the motor significantly. The problem is quite complex, strength, resistance to fatigue, critical speed and natural frequencies are all conflicting parameters that had to be addressed. One unique strength of TURBOdesign1 is the ease by which you obtain a new optimized blade shape for each modification of the wheel design. This way we can experiment with different designs to solve strength and fatigue problems and still very quickly obtain the optimum blade shape. Once again, the capacity tests made on the first prototype were very convincing. The fan impeller diameter was reduced considerably without compromising performance and, very importantly, efficiency”.

“TURBOdesign1 has given new answers to really challenging problems” concludes Eriksson “it also raises new questions… Now we realise that it is only our own imagination that sets the limits to how we can develop optimum solutions for coming projects. With TURBOdesign1 we will raise the concept of ‘tailor-made’ fans to a new and much higher level.”

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