Penetration of a blade into a vortex core: vorticity response and unsteady blade forces
Penetration of a blade into a vortex core: vorticity response and unsteady blade forces
复制标题
叶片侵入涡核：涡度响应和非定常叶片力
DOI：
10.1017/s0022112096001243
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发表时间：
1996
影响因子：
3.7
通讯作者：
J. R. Grant
中科院分区：
文献类型：
--
作者：
J. Marshall;J. R. Grant
对垂直于涡轴运动的叶片的涡核穿透问题进行了数值计算，其中叶片跨度和叶片运动方向形成的平面与穿透点处的涡轴法面重合。计算基于一种适用于浸没物体三维非定常流动的计算方法，该方法在一组拉格朗日控制点上得到涡量输运方程的配置解。讨论了该方法与文献中其他基于拉格朗日涡度的方法的区别。这种拉格朗日方法对于非定常涡体相互作用问题特别有吸引力，因为控制点只需要放置在物体表面和具有不可忽略的涡量的流动区域。对无粘流体中的法向叶片-涡间干扰(BVI)进行了计算，重点研究了叶片穿透到涡圈周围位置所引起的涡核变形与由此产生的非定常压力场和作用在叶片上的非定常作用力之间的关系。对不同旋涡环流的情况进行了计算，并与非定常叶片力的完整计算结果进行了比较，验证了基于快速变形理论的近似公式的精度。研究发现，叶片穿透到涡旋周围位置所产生的力与其他各种非定常BVI力的大小相当，例如涡轴向流的切割所产生的BVI力。
Numerical calculations are performed for the problem of penetration into a vortex core of a blade travelling normal to the vortex axis, where the plane formed by the blade span and the direction of blade motion coincides with the normal plane of the vortex axis at the point of penetration. The calculations are based on a computational method, applicable for unsteady three-dimensional flow past immersed bodies, in which a collocation solution of the vorticity transport equation is obtained on a set of Lagrangian control points. Differences between this method and other Lagrangian vorticity-based methods in the literature are discussed. Lagrangian methods of this type are particularly attractive for problems of unsteady vortex-body interaction, since control points need only be placed on the surface of the body and in regions of the flow with non-negligible vorticity magnitude. The computations for normal blade-vortex interaction (BVI) are performed for an inviscid fluid and focus on the relationship between the vortex core deformation due to penetration of the blade into the vortex ambient position and the resulting unsteady pressure field and unsteady force acting on the blade. Computations for cases with different vortex circulations are performed, and the accuracy of an approximate formulation using rapid distortion theory is assessed by comparison with the full computational results for unsteady blade force. The force generated from blade penetration into the vortex ambient position is found to be of a comparable magnitude to various other types of unsteady BVI forces, such as that due to cutting of the vortex axial flow.