Research on combustion flow field imaging method based on ray casting algorithm

Measurement of flame or combustion is an important method to estimate combustion quality, study the performance of engine and develop renewable energy sources. This paper presents a method to detect the combustion flow field in a confined space using Positron Emission Tomography (PET) technology. Radionuclides are labelled in aviation kerosene, and the nuclides are distributed in the confined space along with the kerosene in the process of combustion. γ photons generated by the decay of the nuclides in the combustion region are detected by the detectors around the object. Each pair of γ photons with 511keV travelling in opposite directions within a short time window are detected as a line of response (LOR). The distributions of nuclide concentrations in the combustion region, which are related to the combustion flow field, are estimated through the counts of LORs at different angles and positions. In order to display the combustion flow field based on human visual features, ray casting algorithm is used to reconstruct the 3D image with the slice images got from PET. Due to the complexity of ray casting algorithm, the interpolation algorithm in ray casting algorithm is optimized. The experiment results show that the image construction speed is improved with the optimized ray casting algorithm. The constructed 3D image can display the combustion flow field from different viewpoints.