Investigation of Layer Thickness and Surface Roughness on Aerodynamic Coefficients of Wind Tunnel RP Models

Authors: S. Daneshmand, A. Ahmadi Nadooshan, C. Aghanajafi

Abstract:

Traditional wind tunnel models are meticulously machined from metal in a process that can take several months. While very precise, the manufacturing process is too slow to assess a new design's feasibility quickly. Rapid prototyping technology makes this concurrent study of air vehicle concepts via computer simulation and in the wind tunnel possible. This paper described the Affects layer thickness models product with rapid prototyping on Aerodynamic Coefficients for Constructed wind tunnel testing models. Three models were evaluated. The first model was a 0.05mm layer thickness and Horizontal plane 0.1μm (Ra) second model was a 0.125mm layer thickness and Horizontal plane 0.22μm (Ra) third model was a 0.15mm layer thickness and Horizontal plane 4.6μm (Ra). These models were fabricated from somos 18420 by a stereolithography (SLA). A wing-body-tail configuration was chosen for the actual study. Testing covered the Mach range of Mach 0.3 to Mach 0.9 at an angle-of-attack range of -2° to +12° at zero sideslip. Coefficients of normal force, axial force, pitching moment, and lift over drag are shown at each of these Mach numbers. Results from this study show that layer thickness does have an effect on the aerodynamic characteristics in general; the data differ between the three models by fewer than 5%. The layer thickness does have more effect on the aerodynamic characteristics when Mach number is decreased and had most effect on the aerodynamic characteristics of axial force and its derivative coefficients.

Keywords: Aerodynamic characteristics, stereolithography, layer thickness, Rapid prototyping, surface finish.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1082231

References:

[1] Cho, I., Lee, K., Choi, W., Song, Y. "Development of a new type rapid prototyping system", International Journal of Machine Tools & Manufacture, vol. 40, no. 4, pp.1813-29, 2000.
[2] Richard J. Hildebrand and Robert C. Eidson , "Development of a low cost, rapid prototype lambda wing-body wind tunnel model,"21st Applied Aerodynamics Conference (AIAA) Orlando, Florida 23-26 June 2003.
[3] Steve Upcraft, Richard Fletcher, "The rapid prototyping technologies," Journal of Assembly Automation, vol. 23, no. 4, pp. 318-3308, 2003.
[4] Onuh, S. O. "Rapid prototyping integrated sys-tems" Rapid Prototyping Journal, vol. 7, no. 4, pp. 220-225, 2001.
[5] Rn Chuck and Vj Thomson, "A comparison of rapid prototyping techniques used for wind tunnel model fabrication," Rapid Prototype Journal, vol. 4, no. 4, pp. 185-196, 1998.
[6] Guanghua Sui, Ming C. Leu, "Surface roughness visualization for rapid prototyping models," Journal of Computer-Aided Design, vol. 34, Pages 717-725, September 2002.
[7] S.0. Onuh and K.K.B. Hon, "Optimizing Build Parameters for Improved Surface Finish in Stereolithography," Journal of Machine Tools and Manufacture, vol. 08, no. 4, pp. 329-342, 1998.
[8] R.E. Williams, S.N. Komaragiri, VL. Melton, and R.R. Bishu , "Investigation of the Effect of Various Build Methods on the Performance of Rapid Prototyping (Stereolithography)" Journal of Materials Processing Technology, vol. 61, no. 4, pp. 173-178, 1996.
[9] Chua, C.K., Leong, K.F. and Lim, C.S,"Rapid Prototyping Principles and Application", 2nd Ed, World Scienti.c, New Jersey, NJ, 2003.
[10] Trowmans, G., Winpenny, D, "Rapid manufacturing", 4th European Conference on Rapid Prototyping & Manufacturing, University of Nottingham, Belgirate, Italy, pp.653-670, 2002.
[11] http://www.matweb.com
[12] Jones, Pandey, R.T., "The Oblique Wing craft design for Transonic and Low Supersonic Speeds," Acta Astronautic, Vol. 4, 1999, PP 158-169.
[13] A. Springer, "Evaluating Aerodynamic Characteristics of Wind-Tunnel Models Produced by Rapid Prototyping Methods," Journal of Spacecraft and Rockets, vol. 35, no. 6, pp. 755-759, 1998.
[14] Springer, A.; Cooper, K.; and Roberts, F. "Application of Rapid Prototyping Models to Transonic Wind tunnel Testing. AIAA 97-0988, 35th Aerospace Sciences Meeting. January 1997.
[15] Springer A., Cooper K., "Comparing the Aerodynamic Characteristics of Wind Tunnel Models Produced by Rapid Prototyping and Conventional Methods,"AIAA 97-2222, 15th AIAA Applied Aerodynamics Conference, June 1997.