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Large Riblet Surface with Super Hardnesss, Mechanical and Temperature Resistance by Nano Functionalization

Periodic Reporting for period 3 - ReSiSTant (Large Riblet Surface with Super Hardnesss, Mechanical and Temperature Resistance by Nano Functionalization)

Reporting period: 2021-01-01 to 2021-12-31

The European innovation project »ReSiSTant« that started on January 1 st 2018 with a term of four years aims at optimizing two industrial pilot lines by using micro- and nanostructured surfaces for drag reduction. The objectives are to implement new developed surfaces into 1) Aircraft Turbofan Engines and 2) Industrial Compressors. Positive effects by usage of such surface could give benefits in terms of efficiency, CO2 reduction and noise emission and further on a positive economic and ecological impact. Despite the effectiveness of the riblets as passive devices for drag reduction being undoubted, and the mechanism for which this happens having been clearly demonstrated for a couple of decades, a verification of this capability has not been proven to date in full detail, due to the difficulties of the experiments, the lack of the numerical models and mainly the appropriate materials. To enable the usage of such micro- and nanostructures, special development on the surface material for better durability in rough conditions has to be done. It is planned to do nano-functionalization, like implementing nanostructures and nanoparticles for better resistance in rough conditions. Riblets basically consist of tiny streamwise grooved surfaces which reduce the drag in the turbulent boundary layer of up to 8%. Surface modifications such as riblets are the most promising technology that could be applied without additional external energy or additional amount of air. The project aims at developing innovative manufacturing technologies by implementing nanostructures and nanoparticles and it will be assured by two demonstrator lines. During this project, the main efforts for technology advancement will be dedicated to 1) the demonstration of production of large scale high ReSiSTant nano- and microstructured surface on two demonstrators 2) the combination of different process technologies and steps in order to demonstrate the complete fabrication chain for the two selected application demonstrators, and 3) setting-up of an industrial demonstrator in two different fields (industrial compressors and aircraft turbofans).
During the first project 18 months simulation of the riblet sizes for all demonstrators and efficiency increase for that have been developed. CFD analysis has been done and the mesh refined for riblet simulations to obtain the distribution of Reynolds numbers, the flow field and the wall shear stress distribution within the test rigs. A precise simulation of the benefit of riblets in a turbofan jet engine and an industrial compressor was done. Feasibility study of the material for all demonstrators has been also carried out. Different materials were first analysed individually screening raw materials and coatings for high temperature riblet coatings. Moreover development of materials has been done with the target of achieving the desired dimensions (micrometer scale) and further testing has been done to optimize the polymeric matrix and validate the process. First time high temperature resistant microstructured riblets where produce and tested on a plate plate. A number of transversal activities as Communication and Dissemination, Exploitation and IPR (Intellectual Property Rights) protection activities have been undertaken and other ones are already foreseen for the next 6 months (e.g. SciTech 2020 in Orlando).
One of the primary targets of ReSiStant project is the optimization of two industrial pilot lines by using micro and nano-structured surfaces for drag reduction. During the project a riblet coating that includes a corrosion protection should be developed, and the surface manufacturing process shall be completed in less than 5 hours in a reliable and predictable manner. The project will furthermore contribute to relevant socially important impacts as:
• unlock the potential of aircrafts, airline companies and industries to actively contribute to the achievement of the 2030 and 2050 climate change and energy policy objectives, by increasing turbomachinery efficiency and reducing related emissions
• promote the renovation of EU aircraft fleet with more efficient aircraft less wear affected and with a larger lifetime (30 years)
• promote aircraft noise reduction as stated by Regulation (EU) No 598/2014, facilitating aircraft manufacturers to realize high efficiency and less noisy aircraft engines (-8%) without additional silencer and filters instrumentations (Weight and costs)
• contribute to consolidate the leading role of Europe in Aviation MRO and aircraft turbine engine manufacturing, increasing expertise and know-how
• establish market opportunities for new nanotechnologies products and services, thus stimulating companies’ growth and the creation of job opportunities and the replication of nanoriblets also in other sectors (marine, automotive, wind power etc.).
Poster of the ResisTant project.