A comprehensive analysis on the structure of groove-induced shock waves in a linear turbine

A shock wave mostly occurs around a compression corner in supersonic flow and, when the corner is followed with another, two shock waves normally generate and, between them, an intersection is possible because of the increased shock angle of the downstream shock. A grooved-surface can generate multiple-shockwave structure in a local supersonic flow field as well. Different from the shockwave structure resulted from the compression corners, its structure may be approximately parallel or divergent when an additional expansion process occurs between two adjacent shock waves. This paper focuses exclusively on the shockwave structures based on both experimental and numerical methods. The physical mechanism for the generation of the approximately parallel and divergent shockwave structures is understood and then the approximately parallel shock wave structure is proved to belong to the same family with the divergent one. In addition, the relationship of the total oblique shock loss with the groove number is analyzed theoretically and numerically in entropy.