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提出了一种顾及位置偏差与凹部同异性的面状居民地Morphing变换转向角函数方法.该方法通过构造大比例尺居民地的凸包作为中间图形,辅助与小比例尺居民地进行特征顶点匹配,避免因位置偏差造成的特征点误匹配;针对大比例尺居民地的凹部,依据凹部的模式类型,判定凹部边的同异性;最后构建插值模型,得到中间任意尺度下的面状居民地要素... 相似文献
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对同一线状要素的不同比例尺表达,借鉴Douglas-Peucker线状要素简化算法思想分别建立BLG树,通过对两BLG树从根结点到叶子结点进行层次匹配将两线状要素对应分割成多对线段。在此基础上,借助线性插值算法进行Morphing变换。实验结果证明,此方法有效保持了原线状要素的结构特征,提高了Mor-phing变换精度,改善了Morphing变换效果。 相似文献
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This work addresses the experimental and numerical study of a stepped planing hull and the related fluid dynamics phenomena typically occurring in the stepped hull in the unwetted aft body area behind the step. In the last few years, the interest in high-speed planing crafts, with low weight-to-power ratios, has been increasing significantly, and, in such context, naval architects have been orienting toward the stepped hull solution. Stepped planing hulls ensure good dynamic stability and seakeeping qualities at high speeds. This is mainly due to the reduction of the wetted area, which is caused by the flow separation occurring at the step. This paper presents the experimental results of towing tank tests in calm water on a single-step hull model, which is the first model of a new systematic series. The same flow conditions are analyzed via Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES), with different moving mesh techniques (overset/chimera and morphing grid), performed at different model speeds. The numerical results are in accordance with experimental data, and overset/chimera grid is found to be the best approach between the analyzed ones. The flow patterns obtained numerically through LES on a refined grid appear similar to the ones observed in towing tank investigations through photographic acquisitions. These flow patterns are dominated by a rather complex 3D arrangement of vortices originating from air spillage at both sides of the step. The understanding of these phenomena is important for the effectiveness of stepped hull designs. 相似文献
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This paper presents a theoretic implementation method of Morphing Unmanned Submersible Aerial Vehicle (MUSAV), which can both submerge in the water and fly in the air. Two different shapes are put forward so that the vehicle can suit both submergence and flight, considering the tremendous differences between hydrodynamic configuration and aerodynamic configuration of a vehicle. The transition of the two shapes can be achieved by using morphing technology. The water-to-air process, including water-exit, morphing, take-off and steady flight, is analyzed. The hydrodynamic and aerodynamic model of the vehicle exiting the water surface obliquely and then taking off into the air has been founded. The control strategy after morphing is analyzed and the control method is given. Numerical method is used to validate the motion model of the water-exit process. Results of simulations show the validity of the proposed model and the feasibility of MUSAV in theory. 相似文献
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针对多尺度表达中同名线要素的变换问题,提出一种层次特征点控制下的线状要素Morphing变换方法,在已有的线性插值Morphing变换基础上,利用层次特征点对线要素进行分段控制,按对应弧段的结点的相对位置在本弧段的相同的相对位置处插入点,提高插值过程中点的位置对应精度,使中间比例尺的插值表达得到优化,提高Morphing变换的精度。 相似文献
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