Aerodynamic Design Of Forward Fuselage Using Nurbs With Engineering Constraints

The study focuses on the aerodynamic redesign of forward fuselage of a typical transport passenger aircraft. An aircraft forward fuselage will give a significant impact on the aerodynamic characteristics if it is not designed properly. The supersonic zone over the cockpit not just increases the drag, but also causes noise, so it is a must to do some aerodynamic design works to the forward fuselage to reduce the nose drag and eliminate the supersonic zone as far as possible.Conic curve is mostly used in traditional aircraft design process due to its good aerodynamic characteristics, but its ability of shape deformation is limited to its single control parameter, while flexible shape deformation is the main characteristic of NURBS (Non-Uniform Rational B-Splines) curve. NURBS curves and surfaces are applied to realize shape parameterization and generate flexible geometric representation for the forward fuselage in the research, where related constraints are cooperated in the parametric modeling. Relative lengths and angles are used to describe the control points of NURBS curves. At the beginning, the NURBS geometric methods of the nose control curves are given due to the single-curvature windshield nose shape characteristic, and then get the nose models. After that, a transverse control curve is added at windshield area to further improve the local airflow. Noses with three different kinds of windshield: plane, single-curvature and double-curvature are analyzed and compared using CFD.Results from the research showed that the method can be applied to the redesign of detailed aerodynamic surfaces with complex engineering constraints. Results also showed the advantages and disadvantages of different kinds of windshield. The data and conclusions from the research are valuable for deep understanding the nose aerodynamic optimization design.