Mach’s Contribution to the Development of Gas Dynamics

Abstract

In these days the name of Ernst Mach is most often related to the well-known Mach number, a quantity which has become very popular since flying at supersonic speeds has developed so rapidly. If one takes a look at a textbook of aerodynamics or gas dynamics the name Mach appears in connection with other terms: Mach angle, Mach wave, Mach reflection are frequently used aerodynamic expressions. Ernst Mach, indeed, has provided the fundamental research for explaining and defining these terms, and is considered, therefore, with good reason, to be one of the originators of supersonic aerodynamics. In his ballistic experiments he discovered the existence of a bow-shock in front of a flying projectile and, thereby, an essential difference between flights at subsonic and supersonic velocities; he was the first to recognize the real nature of shockwaves in air and their ‘irregular’ reflection pattern; he visualized particular wave phenomena in a supersonic free-gas jet; and he originated the experimental techniques which were necessary to perform those investigations.

The author gratefully acknowledges the assistance of Dr. R. J. Arenz in translating this manuscript.