| In order to improve the bypass ratio and efficiency, the large size fan has been used in the commercial turbofan aircraft engine. And the large size fan has become a typical characteristic of civil aviation engine. As typical components of advanced component design technology, the fan blade design has become important technology for the new generation of aviation power. Along with the development of domestic large bypass ratio turbofan engine, the design and verification problem of engine airworthiness has become the concern technology for the academia and industry. As the forefront and the most typical components, the airworthiness design and verification of the fan blade is the typical representative technology. Based on the airworthiness design and verification of the civil aircraft engine fan blade, the theory and verification method are investigated comprehensively. The technology of parameter modeling and structure optimization, vibration of airworthiness design and verification, bird impact of airworthiness design and verification, ice impact and equivalent safety, conformity simulation platform has been introduced to carry out the design and verification of the civil aircraft engine fan blade. Through a wide range of numerical analysis and component verification, the risk of engine test can be reduced, and the success rate of airworthiness certification would be improved. The main works of the dissertation are as follows:(1) For the complex modeling problem of wide-chord, swept-curved, and large aircraft engine fan blade, the parametric and robustness optimization research has been carried out. Based on the feature modeling technology, the fan blade geometry is constructed through the airfoil, the circular arc tenon, the fillet section of the three characteristics of parameterized parametric modeling method. The fan blade airfoil is designed and stacked by the third Non-Uniform Rational B-Spline. The modeling difficulty of fan blade circular-arc tenon between the center of ends and the center of gravity point has been solved. And the smooth transition difficulty between free curved face and rectangular cross section has also been solved. The automation forming of the fan blade is achieved by the UG/Open API development. On the basis of the fan blade structure parameters, the robust optimization design method is further introduced. According to four sections of the fan blade and DOE method, approximate response surface model of weight, static strength, vibration, bird impact has been constructed. The robust optimization design for fan blade is realized. The fan blade modeling methods and means have been provided, and the robustness of the fan blade structure is improved. Therefore, the foundations of fan blade design and verification are introduced.(2) For the technical problems of aircraft engine fan blade vibration conformity design and the process involves the verification process, methods, principles, test, etc., the fan blade vibration technical requirements of conformity, compliance process, mode recognition and stress recognition method, parts and components verification, the engine verification methods are provided. And the whole life cycle methods of the fan blade vibration conformity analysis and test are built from the requirement of vibration item. The identification and data processing of vibration stress criterion which includes the core technology such as endurance limit λ, relative strain gauge λ, the relative strain modal λ are constructed. Based on parametric model of fan blade, the simulation analysis method of the fan blade vibration characteristics and vibration stress calculation are introduced. The fan blade vibration stress distribution and high cycle fatigue resistance are verified by the part and component level test. Analysis and test results show that the vibration characteristics and vibration stress level meet the airworthiness design requirements given in this paper. The relative stress analysis result is verified by the test results, and the high cycle fatigue resistance is also been verified. The method and the basis of conformity for fan blade vibration design and verification have also been conducted.(3) For the technical problems of aircraft engine fan blade bird impact conformity design and verification involving different types of bird impact numerical simulation analysis, part level bird impact test, component level bird impact test, the airworthiness requirements and criteria of large bird impact, medium bird, and large flock of birds’ impact are analyzed. The bird constitutive model and the fan blade high strain rate constitutive model are verified by the part level tests. And the fan blade bird impact analysis model is further verified by the high speed impact test. Based on the verified model of bird impact, the simulation methods are used to analyze the fan blade to sustain the ability of large bird, medium bird and large flock of birds’ impact. The critical point analysis(CPA) method of large bird and medium has been formed. And the power decline analysis method after deformation of the fan blade is proposed. The fan blade bird impact conformity design and verification method priority to with the simulation analysis has been realized. Analysis shows that the material loss of fan blade under the large bird impact is less was 27%, and the loss of large flock of birds and medium bird impact power is 18.5%. The fan blade resistance to large bird, large flocks of birds, and medium bird impact ability. The method and model for the fan blade bird impact resistant design and verification are provided.(4) For the aircraft engine fan blade icing and ice impact problems, the weather parameters, the engine condition parameters, icing requirements and the ice impact requirements are introduced. The whole icing process invoking the largest continuous, largest discontinuous, mix biggest frozen, largest take-off, the take-off climb, climb, falling, waiting, approach and landing situation are analyzed. The rotation fan blade icing and ice growth analysis method are provided. Based on the analysis of fan blade icing, ice impact critical point analysis and ice impact model verification, the fan blade icing and ice impact verification method is established from icing condition, spinning icing, ice impact critical point analysis and ice impact. Furthermore, the equivalent level of safety(ELOS) method is induced to apply in the fan blade airworthiness verification. The method of fan blade anti-icing design and verification are provided.(5) For the fan blade airworthiness compliance simulation and optimization problem, the airworthiness simulation test platform theory framework has been proposed consideration parts, engine and data correlation based on the fan blade airworthiness design and verification. And the fan blade airworthiness compliance simulation platform is developed according to the software development specifications. The parametric design integration, the vibration compliance verification, the bird impact compliance verification, the structure optimization design are realized in the platform. |
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