Retrieval of Phase and Temperature Distributions in Axisymmetric Flames From Phase-Modulated Large Lateral Shearing Interferogram

A precise phase modulation and demodulation method was proposed to retrieve temperature distributions in axisymmetric flames by using a single-wavelength large lateral shearing interferometer. A spatial light modulator (SLM) was employed to vary the phases in each pixel continuously in the flame-pha...

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Bibliographic Details
Published in:IEEE transactions on instrumentation and measurement 2021, Vol.70, p.1-12
Main Authors: Tang, Xiaoyang, Cao, Zhang, Wang, Zhonghong, Xie, Heng, Xu, Lijun
Format: Article
Language:English
Subjects:
Air flow
Axisymmetric flame
Demodulation
Fires
Flames
Heating
High temperature
Interference
large lateral shearing interferometer
Optical interferometry
Phase measurement
Phase modulation
phase modulation and demodulation
Pixels
Premixed flames
Refractive index
Shearing
single-wavelength laser
Spatial light modulators
Temperature distribution
Temperature measurement
Thermocouples
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Summary:A precise phase modulation and demodulation method was proposed to retrieve temperature distributions in axisymmetric flames by using a single-wavelength large lateral shearing interferometer. A spatial light modulator (SLM) was employed to vary the phases in each pixel continuously in the flame-phase measurement. The uniqueness of the phase extraction was mathematically proved for the first time, and a least square method was applied to recover the profile of flame phase in the interferometer. The ambiguity of the phases at different cycles of 2\pi was eliminated. The phase shift at each pixel was uniquely determined and verified by using simulated data. Further, precise-phase distributions were utilized to retrieve the temperature distribution in a laminar flame. In actual experiments, four axisymmetric laminar flames from diffused to premixed flames were generated by using a Bunsen burner. Profiles of temperature distribution in the flames were extracted and agreed well with the results scanned by using a thermocouple. With the increase of airflow rate, the position of high-temperature zone was observed moving down, and the thermal structure of the premixed flame became more and more obvious. The preheating zone, reaction front, and reaction zone inside the flames were clearly captured.
ISSN:0018-9456
1557-9662
DOI:10.1109/TIM.2021.3064804