Description of Schlieren Systems
Schlieren Systems let you see shock waves as a combination of bright and dark areas. In the study of supersonic flow, shock and expansion waves are used to determine Mach number. In most situations, however, they are virtually invisible to the naked eye. Fortunately, a system developed in 1864 by German Physicist August Toepler allows waves to be viewed clearly for accurate angular measurements. Schlieren are optical in homogeneities in transparent materials. In supersonic flow, air experiences very large changes in density as it approaches, passes through and trails shock waves. As the density of air changes, so does its index of refraction.
Components of Schlieren Systems