基于曲率控制的B样条飞机进气道几何设计
Geometric Design of B-Spline Aircraft Inlet Based on Curvature Control
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摘要: 进气道能够捕获来流, 按一定流量、流速和畸变向发动机供气. 作为飞机推进系统的起始部件, 进气道直接
影响飞机发动机的工作效率、性能和安全性. 针对进气道自由曲面构型的特点, 提出基于曲率控制的B 样条进气道
几何设计方法. 首先, 给定控制点、节点数据, 构造2 C 光滑约束的B 样条关键截线, 避免产生台阶效应进而影响进
气道性能; 其次, 将计算过渡截线的离散点坐标, 转化为利用过渡截线导数值反求所对应的B 样条曲线, 以减小在
复原曲线过程中计算离散点带来的累积误差; 最后, 将上述B 样条曲线拟合为B 样条张量积曲面结构, 减少格式转
换造成的信息损失. 该技术已集成在某型号进气道建模系统中, 可快速、交互式地完成由任意进气口截线到出气口
截线的光滑过渡. 实验结果表明, 建模得到的进气道曲面结构精确性较高、通用性较好, 一定程度上减少了对国外相
关CAD 航空工业软件的依赖, 为后续基于数值优化的几何设计与流体仿真一体化提供了技术支撑.Abstract: Air inlets are the initial component of the aircraft propulsion system, which is responsible for capturing
the incoming flow and supplying air to the engine according to a certain flow, velocity and distortion.
Thus, they affect both the efficiency and effectiveness of aircraft engines. Aiming at the configuration of the
free-form surface of the air inlet, a B-spline fitting algorithm based on curvature control is proposed for inlet geometric design. First, under the premise of given control points and node data, B-spline key section lines with 2 C smooth constraints are constructed to avoid the side effect of staircases which will degrade the performance of the inlet; second, to reduce the error caused by the discrete points in the process of restoring the curve, the step of calculating the coordinates of the discrete points of the transition section is transformed into the reverse calculation of the corresponding B-spline curve by using the derivative value of the transition section; finally, the above B-spline tensor product surface structure is fitted to reduce the information loss caused by format conversion. The method has been packaged into an inlet modeling system, which can quickly and interactively achieve the arbitrary transition from the air inlet intercept line to the air outlet intercept line. The experimental results show that the obtained inlet surface structures are of high accuracy and possess the generalization ability. Our method can reduce the dependence on foreign CAD related Aviation Industry Software, and provide technical support for the subsequent integration of geometric design and fluid simulation based on numerical optimization.