Research On Fan Improvement Design For D Style Turbofan Engine

Many turbomachineries with super performance has been designed with the aid of traditional quasi-three-dimensional design method, which still play a important role in modern turbomachinery design process, and a lot of design experience has been established. However, for the tendency of High throughflow, High load and High efficiency (3H) turbomachinery, traditional design system starts to show its deficiency. In this dissertation, first, a review on development of fan/compressor design technique has been made; then, based on the traditional design system, a elementary modern fan/compressor design system, which is well suited to the domestic computational capacity now, has been constructed, by including some new design concept. Also, the basic principle and flowchart of aerodynamic process is reviewed briefly.Considering the flow separation, which is frequently met in fan/compressor design process, a deep analysis to the secondary flow in turbomachines is present based on the axis-symmetric inviscid governing equation, the analysis shows that there are three primary factors, which influence the force balance in flow passage. Based on this recognition, an new rule for bowed stator design --- Aero-Orthogonality (AO) rule is proposed here. Experience shows that the rule is very effective in improving surge margin and off-design performance.With the help of the improved design system, a fan stage redesign is conducted, and 3-D flow field calculation verifies that the design object is satisfied. To eliminate flow separation at the tip and hub section, AO rule is applied and the result is satisfactory.Also, A new optimization technique is adopted in the new design system --- Adjoint method, NASA rotor 67 is first redesigned by this method to show its potential of performance improvement, then this method is applied to the rotor of fan stage. The result is fairly encouraging. The rotor efficient get a 2% gain, which means that the adjoint method do improve the three dimensional flow fields, and is indispensable to the new design system.Finally, experiment of the redesigned fan stage at the revolution 25850rpm is conducted, which vertifies that the design system used in this paper is feasible and the redesign work of the fan stage is successful.