Conclusions

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the computer system. Analysis of the final design change was stopped after O(3.5) convergence was

achieved.

Figure 6 shows the Cp and geometry history for the nine design cycles at an inboard cut, the keel line,

and an outboard cut. In this example, left-right symmetry is not maintained. The design is an attempt to

achieve a favourable pressure gradient over the first 50 percent of the nacelle chord, while still allowing

the inboard side of the nacelle to have overall lower Cp levels than the outboard side. This concession is

not necessary, but is typical of the Mach suppression effect seen on the inboard side of an installed

nacelle17. With CDISC one was able to achieve the characteristics of a desired pressure distribution

without compromising the levels of the existing analysis pressure.

Figure 7 is representative of the wing Cp, which was largely unaffected by the design changes to the

nacelle. Although not shown, the wing drag did not change despite the dramatic changes in nacelle Cp.

Conclusions

Tools have been developed for the inverse design of a component of a complete airplane configuration

while it is in the presence and under the influence of the rest of the airplane. Except for the initial grid

generation, which will depend on the particular problem of interest, the design process is automated.

The results showed the specific application of these tools to the design of turbofan nacelles.

Additionally, it was shown that computational cost of the design is of the same order as that of a

comparable analysis.

Acknowledgments

A part of this research is funded by the National Aeronautics and Space Administration, Langley

Research Center, Component Integration Branch, under NASA Contract No. NAS1-19672.

Computational support was provided by the National Aerodynamic Simulation program. The technical

advice of Dr. Richard D. Cedar from General Electric Aircraft Engines is gratefully acknowledged.

References

1. Campbell, R. L.: "An Approach to Constrained Aerodynamic Design with Application to Airfoils,"

NASA-TP-3260, November 1992.

2. Yu, N. J., and Campbell, R. L.: "Transonic Airfoil and Wing Design using Navier-Stokes Codes,"

AIAA CP-92-2651.

3. Smith, L. A., and Campbell, R. L.: "Applications of a Direct/Iterative Design Method to Complex

Transonic Configurations," NASA-TP-3234, September 1992.

4. Lin, W. F., Chen, A. W., and, Tinoco, E. N.: "3D Transonic Nacelle and Winglet Design," AIAA

CP-90-3064.

5. Chen, H. C., Su, T. Y., and Kao, T. J.: "An Installed Nacelle Design Code Using a Multiblock Euler

Solver, Volume I: Theory Document," NASA CR 189652, September 1992.

6. Bell, R. A., and Cedar, R. D.: "An Inverse Method for the Aerodynamic Design of

Three-Dimensional Aircraft Engine Nacelles," Third International Conference on Inverse Design

Concepts and Optimization in Engineering Sciences," October 23-25, 1991.