Bringing Bio-Inspired Riblet Surfaces to Complex Industrial Components within BILASURF

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Bringing Bio-Inspired Riblet Surfaces to Complex Industrial Components within BILASURF

After more than three years of research and development, the EU-funded BILASURF (Bio-inspired laser functionalization of complex 3D industrial surfaces) project has been successfully completed.

The project addressed a central challenge in industrial surface engineering: how can drag-reducing Riblet structures be designed, manufactured and validated on large, curved and rotating components rather than only on simple laboratory samples? BILASURF combined application-specific Riblet design, advanced CFD simulation, high-rate laser processing, multi-axis component handling and inline quality monitoring within one integrated manufacturing approach.

From shar skin to industrial efficiency

Riblets are microscopic surface structures inspired by shark skin. When adapted to the local flow, they can reduce fluid-dynamic friction and improve the efficiency of technical systems. Applying Riblets to industrial components is, however, considerably more complex than structuring a flat surface. Components such as turbine runners and fan blades contain strongly curved geometries, changing flow directions and locally varying operating conditions. The required Riblet dimensions and orientations therefore differ across the component surface.

BILASURF addressed this challenge by combining:

  • CFD-based flow analysis and Riblet design
  • Laser processing of complex surfaces
  • Automated positioning and manufacturing
  • Process monitoring and quality control
  • Validation on industrial demonstrators
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The developed prototype combined the laser-texturing system, positioning technology, control software and monitoring modules required to process large and complex components with a high level of precision. Different manufacturing routes were investigated for the demonstrators. Riblets were generated directly on the Francis turbine surfaces, while a replication route based on structured molds and injection molding was developed for the industrial fan.

The role of bionic surface technologies

At bionic surface technologies GmbH, our central responsibility was the application-specific design and simulation of the Riblet surfaces. Using advanced CFD simulations, we analyzed the local flow conditions, wall-shear stresses and flow directions across the turbine and fan geometries. Based on these results, suitable Riblet dimensions, orientations and application areas were defined for the different components. This targeted the realization of an optimized application strategy to reach the most effective solution with locally adjusted structure geometries while maintaining manufacturability and scalability. BST therefore provided the link between:

industrial application → CFD analysis → Riblet design → manufacturing requirements → performance validation

From components to demonstrators

The developed technologies were evaluated using two industrial demonstrators:

Hydropower turbine: Testing was first conducted on simplified hydraulic profiles and subsequently on a reduced-scale model of a Francis turbine supplied by Global Hydro. Comparative tests with and without laser-structured Riblets investigated their influence on turbine efficiency, flow behavior and cavitation under realistic operating conditions.

Industrial fan: For the fan demonstrator, Riblet structures were adapted to the strongly varying flow conditions across the blades and transferred through a replication-based manufacturing route. Preliminary flow-channel measurements on injection-molded Riblet plates demonstrated a reduction of more than 3% at higher flow velocities compared with the corresponding flat reference surfaces.

Together, the demonstrators showed how simulation, surface design, manufacturing and testing can be combined to move Riblet technology from simplified samples towards complex industrial components.

Moving towards industrial application

With the successful completion of BILASURF, an integrated technology platform for the functionalization of complex 3D surfaces has been established and demonstrated. The next steps concern the further industrialization of the developed technologies:

  • Application-specific pilot projects
  • Further improvement of processing speed and scalability
  • Long-term durability and operational validation
  • Integration into industrial production processes
  • Qualification for additional components and sectors
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For BST, the project provides an important contribution for combining CFD-optimized Riblet designs with scalable laser-based manufacturing technologies. This opens new opportunities to implement drag-reducing surfaces on increasingly complex components in hydropower, HVAC, turbomachinery and other industrial applications. The project concluded with a successful final review meeting at Fraunhofer IWU, where the consortium presented the completed developments and the integrated demonstrator.
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Project Information

Program: Horizon Europe – Made in Europe Partnership
Duration: January 2023 – May 2026
Project budget: Approximately €5.6 million
Grant agreement: 101091623
Coordinator: Ceit Research Center

Project partners: Ceit Research Center, AIMEN Centro Tecnológico, Fraunhofer IWU, Fusion Bionic GmbH, bionic surface technologies GmbH, SuperGrid Institute, Global Hydro Energy, ZIEHL-ABEGG, Workshop of Photonics and secpho.

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