Transition prediction of a hypersonic boundary layer over a cone at small angle of attack--with the improvement of eN method

• 来源期刊: 中国科学G辑(英文版)
• 年，卷（期）: 2009,（1）
• 页码范围: 115-123
• 页数: 9页
• 语种: 英文
• DOI: 10.1007/s11433-009-0006-4

摘要

The problem of transition prediction for hypersonic boundary layers over a sharp cone has been stud-ied in this work. The Mach number of the oncoming flow is 6, the cone half-angle is 5Ω, and the angle of attack is 1Ω. The conventional eN method 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 ac-count, 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 the eN method are proposed. Not only the amplification process but also the decay process is con-sidered. 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 transi-tion 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.