Transition prediction of a hypersonic boundary layer over a cone at small angle of attack—with the improvement of eN method
Transition prediction of a hypersonic boundary layer over a cone at small angle of attack—with the improvement of eN method
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DOI：
10.1007/s11433-009-0006-4
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发表时间：
2009-01
期刊：
影响因子：
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通讯作者：
Caihong Su;Heng Zhou
中科院分区：
文献类型：
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作者：
Caihong Su;Heng Zhou
本文研究了高超声速尖锥边界层转捩的预报问题。来流马赫数为6，锥顶角为5°，攻角为1°。采用了传统的方法，但由此得到的转捩位置显然是不正确的。这是因为传统方法只考虑了放大波，而实际上不同的经线，扰动在开始增长之前的衰减过程是不同的。本文在前人工作的基础上，对该方法提出了新的解释和必要的改进。不仅考虑了放大过程，而且考虑了衰减过程。根据线性稳定性理论，将扰动波振幅从初始较小值放大到1%的位置视为过渡位置。由此得到的转捩预报的新结果是相当令人满意的。同时指出，对于小攻角的底流计算，可以采用边界层方程。它的计算成本比DNS小得多。
The problem of transition prediction for hypersonic boundary layers over a sharp cone has been studied in this work. The Mach number of the oncoming flow is 6, the cone half-angle is 5°, and the angle of attack is 1°. The conventionaleNmethod is used, but the transition location so obtained is obviously incorrect. The reason is that in the conventional method, only the amplifying waves are taken into account, while in fact, for different meridians the decay processes of the disturbances before they begin to grow are different. Based on our own previous work, new interpretation and essential improvement for theeNmethod are proposed. Not only the amplification process but also the decay process is considered. The location, where by linear stability theory, the amplitude of disturbance wave is amplified from its initial small value to 1%, is considered to be the transition location. The new result for transition prediction thus obtained is found to be fairly satisfactory. It is also indicated that for the calculation of base flow, boundary layer equations can be used for a small angle of attack. Its computational cost is much smaller than those for DNS.