Aerodynamic Design of Unmanned and Scaled Supersonic ...

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K. Yoshida and Y. Makino 2) Flow-plug tests for the nacelle flow effect on drag characteristics In order to collect the complete drag data of the NEXST-2 airplane in the system design phase, we had to investigate the mass flow effect of the nacelle on the airframe drag characteristics. Therefore, we produced a large test model with two flow control plugs behind each nacelle shown in Figure 14. This model was a 17.0% scaled model. A flow plug test was conducted in the 2m x 2m transonic wind tunnel of JAXA [27]. Figure 20 shows drag characteristics with respect to mass flow ratio (A0/Ai) of nacelle flow at Mach 1.4. Here A0 and Ai mean the cross-sectional area of actual flow stream tube at forward infinity and the capture area at the front of the intake. The figure indicates an increase of the nacelle drag as the mass flow ratio decreases. The total drag strongly depends on the nacelle drag. Figure 21 shows pressure distributions measured by the pressure sensitive paint (PSP) technique [28] at the typical two cases of small and large values of A0/Ai. As shown in the figure, the strong shock wave was observed in front of the intake at small mass-flow ratio condition. This flow pattern corresponds to the unstart condition. On the other hand, at the condition of large mass flow ratio, there was no remarkable shock wave in front of the nacelle. 4. CONCLUDING REMARKS Nacelle flow effect : M=1.4, α=0°, β=0° CDFc 0.03 C D 0.025 0.02 Wing-Body 0.015 0.01 Nacelle(Left) 0.005 0 -0.005 0 0.2 0.4 0.6 0.8 1 Ao/Ai(Left) A 0 /A i (L Figure 20. Interference test of NEXST-2 : JAXA developed some original advanced design concepts and procedures in the unmanned and scaled supersonic experimental airplane program. The supersonic NLF wing design concept and the CFD-based inverse design procedure were developed for the first airplane. The non-axisymmetrical area-ruled body concept and the CFD-based optimum design procedure were developed for the second airplane. The NLF wing concept was validated in the wind tunnel test qualitatively, but not quantitatively, because of the existence of freestream turbulence in any supersonic wind tunnels. The flight test is expected to validate it both qualitatively and quantitatively. In reducing strong interference drag between the airframe and two large nacelles of the second airplane, the effect of the non-axisymmetrical area-ruled body concept was confirmed numerically. However, the concept has not been validated experimentally, because it is not easy to simulate the complete flowfield around a complicated configuration with engine operation condition in wind tunnel tests. The flight test is valuable in validating the design concept. We expect to continue to develop the advanced aerodynamic design technology after the successful flight test of the NEXST-1 airplane. 0.045 0.04 0.035 Total Plug test (“0-2nd Configuration”) Nacelle flow effect : M=1.4, α=0°, β=0° Ao/Ai=0.33 Ao/Ai=0.86 Figure 21. Interference test of NEXST-2: PSP test (“0-2nd Configuration”) 18
K. Yoshida and Y. Makino ACKNOWLEDGEMENT The authors would like to express special thanks to the Mitsubishi Heavy Industries, Kawasaki Heavy Industries, Fuji Heavy Industries and Tohoku University for their cooperative efforts to the design of experimental airplanes. In addition, a lot of research activities related to those designs were supported by some researchers of JAXA. The authors also would like to thank them. REFERENCES [1] K. Yoshida. Fundamental Research Topics on Aerodynamic Shape of SST – Based on inhouse research reports –. Journal of the Japan Society for Aeronautics and Space Sciences, vol.42, No.486, pp.1-13, 1994 (in Japanese) [2] F. R. S. Kuchemann. The Aerodynamic Design of Aircraft. Pergamon Press, 1978. [3] K. Yoshida. Overview of NAL’s Program Including the Aerodynamic Design of the Scaled Supersonic Airplane. held at the VKI, RTO Educational Notes 4, 15-1~16, 1998. [4] H. W. Carlson and D. S. Miller. Numerical Method for the Design and Analysis of Wings at Supersonic Speeds. NASA TN D-7713, 1974. [5] H. Ashley and M. Landahl. Aerodynamics of Wings and Bodies. Dover Publications Inc., 1965. [6] H. Ogoshi. Aerodynamic Design of a Supersonic Airplane Wing - Application of the Natural Laminar Flow Concept to Airfoil. Proceedings of the 47th National Congress of Theoretical & Applied Mechanics, January, 1998 (in Japanese). [7] Srokowski. Mass Flow Requirements for LFC Wing Design. AIAA 77-1222, 1977. [8] D. Arnal. Boundary layer transition prediction based on linear theory. AGARD Report No.793, 1993. [9] S. Jeong, K. Matsushima, T. Iwamiya, S. Obayashi and K. Nakahashi. Inverse Design Method for Wings of Supersonic Transport. AIAA 98-0602, 1998. [10] R. Takaki, T. Iwamiya and A. Aoki. CFD Analysis Applied to the Supersonic Research Airplane. 1st International CFD Workshop on Supersonic Transport Design, Tokyo, March, 1998. [11] Y. Shimbo, K. Yoshida, T. Iwamiya, R. Takaki and K. Matsushima. Aerodynamic Design of the Scaled Supersonic Experimental Airplane. 1st International CFD Workshop for Super-sonic Transport Design, Tokyo, March, 1998. [12] W. D. Middleton and J. L. Lundry. A System for Aerodynamic Design and Analysis of Supersonic Aircraft. NASA Contractor Report 3351, 1980. [13] K. Yoshida and Y. Ishida and M. Noguchi and H. Ogoshi and K. Inagaki. Experimental and Numerical Analysis of Laminar Flow Control at Mach 1.4. AIAA 99-3655, 1999 19
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