Abstract

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.

Highlights

  • In order to develop renewable energy source and fossil fuels, improve the efficiency of combustion, reduce exhausting emissions, many researchers have studied the measurements of flame or combustion

  • This paper proposes a combustion flow field imaging method based on positron annihilation

  • Radionuclides are labelled in aviation kerosene, and the nuclides are distributed in the confined space along with the fuel burning

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Summary

INTRODUCTION

Measurements of flame or combustion have received considerable attention due to its importance in engines. In order to develop renewable energy source and fossil fuels, improve the efficiency of combustion, reduce exhausting emissions, many researchers have studied the measurements of flame or combustion. Haipeng J. studied flame propagation behaviors and temperature characteristics in pulverized biomass dust explosions. Han Yu studied radiationinduced uncertainty in laminar flame speed. For a long time in the past, using sensors to test pressure, using Pitot tube to test speed and using thermocouple to test temperature were experimental measurements of flow field parameters. They are far from meeting the requirements of the development of modern science and technology on flow field testing and display, especially when it comes to the combustion flow field testing which is high-temperature, high-pressure and high-speed. Goldenstein used infrared laser-absorption sensor to test combustion gases.. Goldenstein used infrared laser-absorption sensor to test combustion gases.7 These methods still can’t measure the combustion or flame inside engines. A method based on PET to detect and visualize the internal combustion flow field is proposed. It is possible to image the combustion flow field inside the combustion chamber

FUNDAMENTALS
EXPERIMENTS
COMBUSTION FLOW FIELD IMAGING BASED ON LORs
Principle of the ray casting algorithm
Resampling and interpolation calculations
Image synthesis
The optimization of interpolation algorithm
Experiment results and analysis
CONCLUSIONS

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