Formation mechanism of the reflected shock wave over curved surfaces.

曲面反射冲击波的形成机制。

• 批准号: 08650220
• 负责人: KOBAYASHI Susumu
• 金额: $ 1.28万
• 依托单位: Saitama Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650220/
• 关键词: shock wave; reflection phenomena; unsteady reflection; formtion mechanism; tramsition wedge angle; weak shock wave

Shock reflection phenomena over curved surfaces have been investigated both experimentally and theoretically. The models used in this experiment are ordinary circular cylindrical concave and convex wedges and step-like models which simulate the former. The step-like models were used to investigate the process of reflected wave formation over circular cylindrical wedges. The present experimental method by use of step-like models are dubbed method of multiple steps by our research group.The reflected wave structure has been photographed with a schlieren apparatus. The formation mechanism of the reflected wave over circular cylindrical wedges is physically well understood by comparing it with shock reflection over step-like models. In particular, the reason why the reflected wave over a concave circular cylindrical wedge is very weak away fl.om the reflection point is elucidated. Moreover the structure and the formation mechanism of the so-called transitioned regular reflection (TRR) are illustrated in detail. By considering the behavior of the compression wave issued from the step, an analytical formula for the transition wedge angle is proposed and found in good agreement with thc experiment.We were also interested in the effect of some parameters (initial wedge angle, incident shock Mach number and radius of curvature) over the transition wedge angle. The experiment has been performed to investigate such effects. When the initial wedge angle of the concave wedge increases, the analytical formula derived for zero initial wedge angle does not give the correct value. A theoretical method to calculate transition wedge angle was proposed and in good agreement with experiment. Comparison with another method shows this is a far better method for predicting the transition wedge angle.

本文从实验和理论两方面研究了激波在曲面上的反射现象。本实验所用的模型是普通的圆柱形凹楔和凸楔，以及模拟圆柱形凹楔的台阶状模型。采用阶梯模型研究了圆柱形楔体上反射波的形成过程。本课题组将目前采用台阶模型的实验方法称为多台阶法，并用纹影仪拍摄了反射波结构。通过与台阶模型上的激波反射的比较，从物理上很好地理解了圆柱楔上反射波的形成机理。特别阐明了反射波在凹圆柱体上的反射点处很弱的原因。fl.om此外，还详细地阐述了所谓的过渡规则反射（TRR）的结构和形成机理。考虑到台阶产生的压缩波的特性，本文提出了一个与实验符合较好的转捩楔角的解析公式，并讨论了一些参数（初始楔角、入射激波马赫数和曲率半径）对转捩楔角的影响。我们进行了实验来研究这种影响。当凹楔的初始楔角增大时，由零初始楔角导出的解析公式不能给出正确的数值。提出了一种计算过渡楔角的理论方法，并与实验结果进行了比较。与另一种方法的比较表明，这是一个更好的方法来预测过渡楔角。

项目成果

S.Kobayashi: "On the formation mechanism of von Neumann reflection" Proceedings of the 21st International Symposium on Shock Waves. (印刷中). (1998)

S.Kobayashi：“论冯·诺依曼反射的形成机制”第 21 届国际冲击波研讨会论文集（1998 年）。

T.Adachi: "Unsteady shock reflection:influence of initial wedge angle." Proceedings of the 21st International Symposium on Shock Waves(印刷中).(1998)

T.Adachi：“非定常冲击反射：初始角楔的影响。”第 21 届国际冲击波研讨会论文集（正在出版）。（1998 年）

T.Suzuki, T.Adachi, S.Kobayashi: "Nonstationary shock reflection over non-straight surfaces : an approach with a method of multiple steps." Shock Waves. 7. 55-62 (1997)

T.Suzuki、T.Adachi、S.Kobayashi：“非直表面上的非平稳冲击反射：一种多步骤方法。”

S.Kobayashi, T.Adachi, M.Satoh, T.Suzuki: "On the formation mechanism of von Neumann refletion" Proceedings of the 21st International Symposium on Shock Waves. (in press). (1998)

S.Kobayashi、T.Adachi、M.Satoh、T.Suzuki：“论冯诺依曼反射的形成机制”第 21 届国际冲击波研讨会论文集。

T.Adachi, M.Satoh, S.Kobayashi, T.Suzuki: "Unsteady shock reflection : influence of initial wedge angle." Proceedings of the 21st lnternational symposium on Shock Waves. (in press). (1998)

T.Adachi、M.Satoh、S.Kobayashi、T.Suzuki：“不稳定冲击反射：初始楔角的影响。”