多孔介质内火焰分布电容成像测量的在线标定法

On-line Calibration Method for Combustion Visualization in Porous Media by Using Electrical Capacitance Tomography

电容层析成像技术(electrical capacitance tomography,ECT)是一种快速多维场测量技术,它不干扰流场,适用于对多孔介质中火焰分布的可视化测量。因不同燃烧状态下火焰的介电特性未知,测量时必须对ECT进行在线标定。该文针对通道型多孔介质的结构,经适当简化,导出了测量电容与被测物质介电常数的标定关系式,根据该关系式提出一种三点标定法。采用有限元仿真方法进行了验证,结果表明,三点标定法误差小于1%。将该方法用于多孔介质燃烧的在线标定与测量,取得了较好的结果。

Electrical capacitance tomography （ECT） is a fast, multi dimensional measurement technique. It is nonintrusive and non-destructive and can be used for imaging combustion in porous media. It is preferable to calibrate an ECT system on-line, for it is difficult to determine the permittivity of flame under different combustion conditions. Relationship between the measured capacitances and the permittivities of the porous media was derived by an appropriate simplification. A three-point calibration method was presented. The finite element simulation results indicate that the relative errors of the new method are less than 1%. On-line experiments demonstrate the effectiveness of the new method.