Horizontally and vertically sensitive schlieren and shadowgraph system

Abstract

Visualizing and quantifying certain variables are essential in fluid flow studies. If we add that these tasks should be achieved in great detail, it would be beneficial to implement optical techniques that would reveal these characteristics. Based on this premise, we present a z-schlieren setup that allows simultaneous recording of horizontal and vertical sensitivity schlieren images and shadowgraph images. These two visualization techniques complement each other since each method has its own strengths and weaknesses. The optical system employs two ultra-thin filters, an RGB light-emitting diode (LED), and a color digital camera. As a result, the data obtained are significantly improved over the existing standard schlieren methods. Furthermore, the fluid flow is better analyzed by combining the schlieren and shadowgraph techniques since a straightforward optical system gathers helpful information. The performance of the optical system is demonstrated by visualizing the convective fluid flow of a candle flame and measuring the temperature fields of the flow of a heated rectangular plate.