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Experimental and numerical study of shock wave interactions near axis of symmetry

对称轴附近冲击波相互作用的实验和数值研究

基本信息

批准号：
13650165
负责人：
SAIT0 Tsutomu
金额：
$ 2.3万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650165/
关键词：
Shock wave Regular reflection Irreglar reflection CFD Steady reflection Unsteady reflection Unstructured grids Solution adaptive grids 軸対称流れキーワード正常反射 Mach反射軸対称衝撃波衝撃波斜め反射 CFD 非構造格子自動格子細分化

项目摘要

Courant and Friedrics has shown in 1948 that only the irregular reflection (Mach reflection) is possible as a shock wave reflection pattern in an axi-symmetric flow. This drew much attention in the shock wave research community since regular and irregular shock reflections are both possible in shock tube experiments. Extensive investigations were carried out by many researchers and quite a few experimentally obtained images that seem to present regular reflections were reported. However, it is claimed that those images are due to insufficient resolution of the experiments and the decisive conclusions on this subject is not yet made.Under this research project, a shock capturing numerical scheme with unstructured solution-adaptive grids was developed and applied to the subject of shock wave reflection on the axis of axi-symmetric flow. The numerical simulations were done with the high spatial resolution that is difficult to achieve experimentally. And it is found out that the reflection pattern is indeed irregular even when an experimental image showed it to be the regular reflection. This is one of the indications that the numerical simulations are quite important for this research subject.In 1992 Sokolov proposed a gasdynamic mechanism that a shock wave strengthens as it approaches to the axis of symmetry and, as a result, its incident angle always exceeds the transition angle. On the other hand, the non-stationary nature of shock reflections in that a irregular shock reflection always starts as a regular reflection due to viscosity, heat conduction and other non-equilibrium phenomena has been reported. It is now necessary to extend this research subject including such physical phenomena.

Courant和Friedrics在1948年指出，在轴对称流动中，只有不规则反射（马赫反射）才可能成为激波反射图。这引起了激波研究界的广泛关注，因为在激波管实验中，规则和不规则的激波反射都是可能的。许多研究人员进行了广泛的调查，并报道了相当多的实验获得的图像，似乎呈现规则的反射。然而，有人认为这些图像是由于实验分辨率不足造成的，关于这一问题的决定性结论尚未得出。在本研究项目下，发展了一种具有非结构解自适应网格的激波捕捉数值格式，并将其应用于轴对称流轴上激波反射的问题。数值模拟的高空间分辨率是很难实现的实验。并且发现，即使实验图像显示其为规则反射，反射图案也确实是不规则的。1992年Sokolov提出了一种气体动力学机制，即激波在接近对称轴时会增强，其入射角总是超过转捩角。另一方面，激波反射的非稳态性质，即由于粘性、热传导和其他非平衡现象，不规则激波反射总是从规则反射开始。现在有必要扩大这一研究课题，包括这些物理现象。