The Influence of Process Parameters on the Forming of Riblets during Riblet Rolling

Abstract:

In aeronautics, economic and environmental aspects become increasingly important. As those are very much influenced by the frictional drag of the airplane, a reduction of skin friction which causes a major portion of total aerodynamic drag is desirable. One possible approach for passive drag reduction is the application of riblets small longitudinal grooves orientated in flow direction. Through an adapted rolling process, riblets can be brought into metal sheets on a large scale. For this process a thin high-strength steel wire is wound around a work roll to structure it with the negative riblet imprint. In a subsequent step the riblet profile is rolled into the sheet material. Different parameters can influence the process and the quality of the resulting riblet structure. Those parameters that depend on the sheets sheet thickness, material strength, and composition of the sheet are discussed in this paper. Form filling is used as an indicator for riblet quality. It is found that decreasing sheet thickness is beneficial for form filling, but a process dependent minimum sheet thickness exists for which this effect will reverse. Material strength is found to have a much smaller influence on form filling. Nevertheless, harder alloys seem to need a slightly smaller thickness reduction, but higher rolling forces and pressures to achieve desired form filling. Using clad instead of bare materials has a positive influence on form filling and riblet structuring. Furthermore, riblet rolling does not reduce the fatigue strength of the clad material.

• Periodical: Key Engineering Materials (Volumes 611-612)
• Pages: 715-722
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.611-612.715
• Online since: May 2014
• Authors: Julia Pöplau*, Sebastian Stille, Thijs Romans, Tilmann Beck, Lorenz Singheiser, Gerhard Hirt
• Keywords: Rolling , Drag Reduction, Riblets, Roll Structuring, Skin-Friction, Surface Structuring

References

[1] D. Bechert, M. Bruse, W. Hage, J. van der Hoeven, G. Hoppe, Experiments on drag-reducing surfaces and their optimization with an adjustable geometry, Journal of Fluid Mechanics 338 (1997) 59-87.

DOI: 10.1017/s0022112096004673

[2] B. Dean, B. Bhushan, The effect of riblets in rectangular duct flow, Applied Surface Science 258 (2012) 3936-3947.

DOI: 10.1016/j.apsusc.2011.12.067

[3] M. Walsh, Riblets as a Viscous Reduction Technique, American Institute of Aeronautics and Astronautics 21 (1983) 485-486.

[4] H. Choi, P. Moin, J. Kim, Direct numerical simulation of turbulent flow over riblets, Journal of Fluid Mechanics 255 (1993) 503-539.

DOI: 10.1017/s0022112093002575

[5] D. Bechert, M. Bruse, W. Hage, R. Meyer, Fluid Mechanics of Biological Surfaces and their Technological Application, Naturwissenschaften 87 (2000) 157-171.

DOI: 10.1007/s001140050696

[6] J. Reneaux, Overview on Drag Recuction Technologies for Civil Transport Aircraft, European Congress on Computational Methods in Applied Sciences and Engineering, Barcelona, (2004).

[7] M. Thome, G. Hirt, Economical and Ecological Benefits of Process-integrated Surface Structuring, Key Engineering Materials 344 (2007) 939-946.

DOI: 10.4028/www.scientific.net/kem.344.939

[8] G. Hirt, M. Thome, Large area rolling of functional metallic micro structures, Production Engineering Research Development 1 (2007) 351-356.

DOI: 10.1007/s11740-007-0067-z

[9] G. Hirt, M. Thome, Rolling of functional metallic surface structures, CIRP Annals - Manufacturing Technology 57 (2008) 317-320.

DOI: 10.1016/j.cirp.2008.03.034

[10] T. Romans, M. Thome, G. Hirt, Riblet Rolling - Texturing large-area aluminium sheets with riblets, International Aluminium Journal (2009) 54-56.

[11] T. Romans, M. Thome, S. Klumpp, G. Hirt, Walzen feiner Riblet-Oberflächen zur Reduktion von Strömungswiderständen, 25. Aachener Stahlkolloquium, Aachen, 2010, pp.89-98.

[12] B. Denkena, M. Reichstein, B. Wang, Manufacturing of Microfunctional Structures by Grinding, Production Engineering 13/1 (2006) 31-34.

[13] F. Klocke, B. Feldhaus, G. Hirt, M. Thome, S. Klum, Development of Two Innovative Rolling Processes for the Production of Defined Riblet Structures in Consideration of Common Fluid Dynamic Requirements, 2nd International Conference on New Forming Technology, Bremen, 2007, pp.185-194.

[14] W. Hage, K. Knobloch, R. Meyer, Riblet Structures on Compressor Blades of Axial Turbomachines, European Drag Reduction and Flow Control Meeting, Ischia, (2006).

[15] T. Romans, G. Hirt, An analytic, numerical and experimental evaluation of the riblet rolling process, 10th International Conference on Technology of Plasticity, Aachen, (2011).

[16] M. Thome, Umformtechnische Herstellung funktionaler flächiger Mikrostrukturen in metallischen Werkstoffen, in: Umformtechnische Schriften, Shaker Verlag, Aachen, (2009).

[17] J. Schijve, F. Jacobs, Fatigue tests on unnotched and notched specimens of 2024-T3 Alclad, 2048-T8 Alclad and 7178-T6 extruded material, Report TR 68017 Nat. Aerospace Laboratory, (1968).

[18] P. Edwards, M. Earl, A. Britain, A comparative study of the fatigue performance of notched specimens of clad and unclad aluminium alloy, with and without pre-stress, C.P. No. 1361, Aeron. Res. Council, London, (1977).

[19] A. Merati, A study of nucleation and fatigue behavior of an aerospace aluminium alloy 2024-T3, Int. J. Fatigue 27 (2005) 33-44.

DOI: 10.1016/j.ijfatigue.2004.06.010

[20] S. Stille, J. Pöplau, T. Beck, M. Bambach, G. Hirt, Very high cycle fatigue behavior of riblet structured Alclad 2024 thin sheets, Int. J. Fatigue 63 (2014) 183-190.

DOI: 10.1016/j.ijfatigue.2014.01.023