Temperature Field Reconstruction in High-Temperature Gas by Using the Colored Background Oriented Schlieren Method

A 3D temperature field reconstruction method using the colored background oriented schlieren (CBOS) method is proposed to address image blurring due to the different refractive index of the multi-wavelength light and significant errors produced when the traditional background oriented schlieren (BOS) method is applied to high-temperature gas. First, the traditional method is employed to reconstruct the non-uniform 3D temperature field. Second, the CBOS method is applied to correct the distortion. Then, by analyzing the correlation coefficient among different color points of the colored background pattern, the non-uniform temperature field is reconstructed much more accurately. Finally, the experimental results are verified by applying the Runge-Kutta ray-tracing method and the thermocouple contact measurement method. The maximum average temperature error of the CBOS-reconstructed temperature field is 12.92°C, compared with the thermocouples. Therefore, an accurate three-dimensional reconstruction of the temperature field can be achieved by the proposed method effectively.