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821.
822.
As an important index affecting the aerodynamic performance and the structural strength of hollow turbine blades, the wall-thickness precision of the blade is mainly inherited from the positional relationship between the corresponding wax pattern and the internal ceramic core. However, due to locating errors, the actual position of ceramic core is always deviated from the ideal position, which makes it difficult to guarantee the wall-thickness precision of the wax pattern. To solve this problem, a wall-thickness compensation strategy is proposed in this paper. Firstly, based on the industrial computed tomography (ICT) technique and curve matching algorithms, a model reconstruction method is developed, with which the 3D model of a trial wax pattern can be easily constructed. After that, focusing on eliminating the wall-thickness errors of the trial wax pattern, an optimization method for the pose of the ceramic core in the wax pattern is proposed. Then, by mapping the optimal pose of the ceramic core to length adjustments of the locating rods, the wall-thickness errors of the wax pattern can be greatly reduced. A case study is also given to illustrate the effectiveness of the proposed compensation strategy. 相似文献
823.
Minghui ZHANG Zhenli CHEN Zhaoguang TAN Wenting GU Dong LI Changsheng YUAN Binqian ZHANG 《中国航空学报》2019,32(8):1847-1859
Blended-Wing-Body(BWB) configuration, as an innovative transport concept, has become a worldwide research focus in the field of civil transports development. Relative to the conventional Tube-And-Wing(TAW) configuration, the BWB shows integrated benefits and serves as a most promising candidate for future ‘‘green aviation". The objective of the present work is to figure out the effects of the stability margin and Thrust Specific Fuel Consumption(TSFC) on the BWB design in the framework of Multi-Disciplinary Optimization(MDO). A physically-based platform was promoted to study the effect static stability margin and engine technology level. Low-order physically based models are applied to the evaluation of the weight and the aerodynamic performance. The modules and methods are illustrated in detail, and the validation of the methods shows feasibility and confidence for the conceptual design of BWB aircrafts. In order to find out the relation between planform changes and the selection of stability and engine technology level, two sets of optimizations are conducted separately. The study proves that these two factors have dominant effects towards the optimized BWB designs in both aerodynamic shapes, weight distribution, which needs to be considered during the MDO design process. A balance diagram analysis is applied to find out a reasonable static stability margin range. It can be concluded that a recommended stability margin of a practical BWB commercial aircraft can be half of that of a conventional TAW design. 相似文献
824.
Wen-jie Wang Ze-ping Wu Dong-hui Wang Wei-hua Zhang Kun Zhao Patrick N. Okolo Gareth J. Bennett 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(11):3706-3720
Hypersonic vehicles are receiving increased attention within the aerospace community due to their high cruise speed and long-range capabilities. In this paper, a modified Sequential Approximate Optimization method is proposed for an optimized aerodynamic design of a hypersonic vehicle. As part of this approach, a constrained experimental design method is developed to handle the constraints more efficiently. A radial basis function is used to surrogate time-consuming CFD analysis. An efficient and more robust numerical mesh morphing scheme for the hypersonic vehicle is developed for the generation of high-quality meshes. Within this paper, a novel adaptive infilling strategy is proposed which uses an inaccurate search technique coupled with an elite archive. This allows the location of a more promising sample region and hence improves the surrogate accuracy, thereby further enhancing the optimization efficiency. A hypersonic vehicle aerodynamic design problem is solved using the proposed approach and satisfactory results are obtained at much lower computational costs. The lift-to-drag ratio is increased by 23.8% when compared with the base configuration while also satisfying the volume and lift constraints. The pressure and Mach contours have been compared with those of the base configuration and the results demonstrate the strength of the optimized configuration. The modified sequential approximate optimization for designing an improved hypersonic vehicle is worth referencing in future work. 相似文献
825.
眼镜蛇—超大迎角机动的数值仿真分析 总被引:3,自引:1,他引:2
为了搞清完成过失速机动的飞行力学机理,对眼镜蛇机动这种典型的过失速机动动作进行了数值仿真。结果表明,如果能够有效防止横航向偏离,则RSS飞机应该能够完成这类机动飞行。为完成此机动,要求飞机在大迎角下产生足够的低头力矩,而对于发动机推力没有过高要求。气动力迟滞、重心位置、进入速度及高度等因素对动作的具体完成情况,如αmax、θmax、减速性、航迹保持及完成时间有不同形式的影响。 相似文献
826.
827.
范正翘 《北京航空航天大学学报》1996,22(6):671-676
在无刷直流时机的位置伺服系统中,采用了基于状态空间模型的优化设计方法,综合出了次优控制器、建立了广义误差系统状态方程,并利用积分罚函数分段一经法处理伺服系统不等式约束的问题,得出了次优控制算法,经仿真证实,有杉该优化方法设计出的伺服系统的稳态跟踪误差为零;稳成输出不受阶跃干扰的影响;并具有期望的瞬态响应特性。 相似文献
828.
满应力优化设计方法的集约几何规划法 总被引:1,自引:0,他引:1
李来义 《北京航空航天大学学报》1996,22(1):116-120
将集约几何规划法应用在连续梁和刚架的主体优化设计中,计算了两跨连续梁和门式钢框架,均得到满意结果。 相似文献
829.
石油钻井井身轨道设计的优化计算方法 总被引:3,自引:0,他引:3
在井眼轨道设计中.假设井眼轨道上的每一段都是空间平面圆弧或直线段,相互之间在连接处相切。根据这一假设,建立了描述井眼参数之间相互关系的非线性方程组,并采用数值优化理论求解非线性方程组的方法来进行井身轨道参数的数值计算。 相似文献
830.
ACALCULATIONOFOPTIMALFLIGHTTRAJECTORYUSINGTHEPARAMETERIZEDOPTIMIZATIONMETHODACALCULATIONOFOPTIMALFLIGHTTRAJECTORYUSINGTHEPARA... 相似文献