Selection of object plane and arrangement of knife edge for a schlieren system

Schlieren method is an important measurement technology for flow visualization.The device should be systematically regulated before the experiment.Selection of the object plane and arrangement of the knife edge are the key aspects for schlieren information.The light deflection in a flame and the schlieren measurement results of the flame were employed for this work.Characteristics of the images from different object planes were studied and compared.The disappearance of shadows of the tested objects can indeed be considered as a sensitive criterion for accurate focus.Movement direction of the knife edge,focus location and insertion degree of the knife edge were discussed based on the principle of schlieren method and relationship between insertion degree of the knife edge and the schlieren images.This paper will be useful for the flow visualization measurement by means of schlieren method.