WALL-BOUNDED BLADE-TIP VORTEX INTERACTION NOISE
WALL-BOUNDED BLADE-TIP VORTEX INTERACTION NOISE
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壁限叶尖涡相互作用噪声
DOI：
10.1006/jsvi.1996.0791
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
M. S. Howe
中科院分区：
文献类型：
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作者：
R. Dunne;M. S. Howe
本文对低马赫数下刚性叶片方形叶尖与壁面间隙中局部直线涡的声产生问题作了解析处理。叶尖附近的平均流被假定为局部二维，并通过自由流线势流理论进行建模，根据该理论，进入压力侧差距的气流在吸力侧形成壁面射流。假设在涡流通过过程中从叶尖脱落的附加涡量（根据非定常库塔条件）以恒定速度沿着射流的自由流线边界对流。声音由偶极子源产生，其大小和方向由叶片经历的非定常升力确定。我们计算对辐射的单独贡献（即，偶极强度）从涡和脱落涡。当涡流距叶尖的距离与间隙相当时，产生声音，其波长大于1/M，其中M是气流的特征马赫数。该分析的结论得到了另一种简化处理方法的支持，在该方法中，假设通过差距的涡流运动是稳定的，并且脱落涡量在距管道壁固定距离处对流，而不是沿着自由流线。
Abstract An analytical treatment is given of the canonical problem of the generation of sound when a locally rectilinear vortex is drawn through the clearance gap between a wall and the square tip of a rigid blade at low Mach number. The mean flow in the neighborhood of the blade tip is assumed to be locally two-dimensional, and is modelled by free streamline potential flow theory, according to which the flow into the gap on the pressure side emerges as a wall jet on the suction side. The additional vorticity shed from the tip (in accordance with the unsteady Kutta condition) during the passage of the vortex is assumed to convect at constant speed along the free streamline boundary of the jet. Sound is generated by a dipole source, the magnitude and orientation of which are determined by the unsteady lift experienced by the blade. We calculate the separate contributions to the radiation (i.e., to the dipole strength) from the vortex and the shed vorticity. The sound is generated while the vortex is within a distance from the blade tip comparable to the clearance, and has wavelength which is order 1/Mlarger, whereMis the characteristic Mach number of the flow. The conclusions of this analysis are supported by an alternative, simplified treatment in which the vortex motion through the gap is assumed to be steady and the shed vorticity convects at a fixed distance from the duct wall rather than along the free streamline.