2D Temperature Detection Characteristics of Engine Exhaust Gases Using CT Tunable Diode Laser Absorption Spectroscopy

Abstract

Two dimensional (2D) temperature and concentration distribution is related to the combustion structure, the combustor efficiency in engines, burners, gas turbines and so on. Recently, tunable diode laser absorption spectroscopy (TDLAS) as a multi-species measurement technique with high sensitivity and high response has been developed and applied to industrial process monitoring and control technologies in combustion environments. With these engineering developments, transient phenomena such as start-ups and load changes in engines have been gradually elucidated in various conditions. This paper discusses a study of the fast response 2D temperature distribution measurement method based on the combination of TDLAS and Computed Tomographic (CT) reconstruction using absorption spectra of water vapor at 1388nm. The computed tomography tunable diode laser absorption spectroscopy (CTTDLAS) method was appliedtoengine exhausts for 2D temperature distribution measurements. The measured 2D temperature showed better characteristics compared with the temperature measured by a thermocouple. Theoretical H2O absorption spectra in the 1388 nm near-infrared region calculated by the revised HITRAN database were used for temperature measurement. For accurate measurement of temperature in combustion gases, the spectroscopic databases were modified using experimentally measured spectral parameters that are not found in the databases. Accuracy of temperature measurement using TDLAS have also been discussed to demonstrate its applicability to various types of combustor.