Research On The Flow Field Imaging And Three-dimensional Visualization Technology In A Combustion Through Gamma Photons

The combustor is an important component of the engine.The distribution of its flow field has great influence on the performance of the engine,so it is significant to detect the flow field in the combustion chamber.But the existing technology will cause interference to the combustion field.Therefore,it is very important for the study of the imaging and visualization technology of combustion field through gamma photons.In order to achieve the imaging of the combustion field with positron emission imaging device,a combustion chamber system can be placed in the detection ring of the imaging device was designed.The method to get the image of the floe field was the use of positron-tagged aviation kerosene as a fuel in the combustion chamber,the combustion medium of the combustor was used as a tracer.Positron radionuclide was distributed in closed space with combustion medium.Positron emission tomography can detect the gamma photon after positron annihilation,and the tomographic images of combustion field can be obtained.Due to the characteristics of the positron emission tomography images,the tomographic images need to be preprocessed.Preprocessing includes the acquisition and analysis of the tomographic images,the enhancement of the grayscale values of the tomographic images,the interpolation of the tomographic images and the encapsulation into a three-dimensional volume data.Three-dimensional reconstruction of three-dimensional volume data used surface rendering and volume rendering methods.An optical model for volume rendering was established.The ray-casting algorithm in volume rendering was studied,and a combustion flow field was drawn for three-dimensional reconstruction.Due to the large amount of calculation of the ray-casting algorithm,optimization of the interpolation algorithm in ray casting and the ray-casting algorithm based on volume data segmentation were used to improve the reconstruction speed.Finally,some interactive functions of reconstructed images were realized based on visualization toolkit,including space transformation,switching image section and extraction of region of interest.