The main conclusions of this exercise are the following:
- 2D methods are operational for unsteady helicopter flow, and they constitute a useful step in developing 3D algorithms
- for a hovering rotor, Euler methods, which capture the rotor wake, give good results for the first calculations made, but additional investigations are necessary on the wake structure,
- in forward flight, only potential methods are operational presently, and they can give good comparisons with experiment if an unsteady, fully conservative algorithm is used; nevertheless, improvements are necessary in code robustness to compute complex blade planforms, and a finite-difference formulation is probably not the best formulation for that purpose,
- the development of more sophisticated methods is necessary for the future; to predict the rotor performance, viscous effects will have to be included in the model.
The work concerns the application of CFD codes for rotor blade design. Starting from a review of existing CFD codes, improvements to the codes and targets for code performance will be defined. These various codes will then be appropriately developed and tested against selected test cases. This will highlight the most beneficial directions for future work in this field.
Review of the current computational methods with respect to their capabilities and validity limitations.
Consideration of anticipated results expected from the various CFD methods. Definition of targets for the improvement and further development of the methods.
Selection of appropriate test cases for the comparison of the methods, adjusted to their different capabilities. Operational conditions considered are: 2-dimensional steady and unsteady;
3-dimensional steady (hover flight) with and without lift;
3-dimensional unsteady (forward flight).
Development, improvement and testing of the various computational methods. Comparison of results with corresponding test data and methods of other partners. Comparison with the targets.
Final assessment of the results in improvement and development of the methods during the 2 years' work. Determination of the most promising methods for further development.
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