Temperature Field Measurements using Thin Filament Pyrometry in a Medium-Scale Methanol Pool Fire

Published

November 29, 2018

Author(s)

Zhigang Wang, Andy Tam, Ki Yong Lee, Anthony Hamins

Abstract

For the first time, a set of measurements were made to characterize the time-varying temperature field in a medium-sized methyl alcohol (methanol; CH3OH) pool fire steadily burning in a quiescent environment. Historically, measurements have been only made at a single location - uncorrelated with other fire locations. These field measurements provide the opportunity to better understand the complex dynamics and temporal thermal structure of a turbulent fire. A digital camera fitted with optical filters and a zoom lens was used to record the high temperature emission intensity of 14 micron diameter SiC filaments oriented horizontally at various heights above a central cross-section of a steadily burning 0.30 diameter methanol pool fire. Camera optics focused on the filaments with a field of view of 0.3 m by 0.6 m high. The filament was observable only for temperatures greater than 1150 K. Experiments collected thousands of frames of 30 Hz video. In a separate experiment, a 50 micron thermocouple was used to acquire 3400 independent measurements of temperature at a number of locations in the high temperature zone of the fire. A correlation was developed between the probability density functions of the radiation-corrected thermocouple measurements and the filament intensity for the same fire locations. This correlation related the instantaneous filament temperature to the camera grayscale pixel intensity. Assuming a Gaussian temperature distribution, a fitting routine was used to determine the mean temperature and its variance from the calculated filament temperature. The mean temperatures compared favorably to previously reported measurements by Weckman. False-color maps of temperature were produced characterizing the entire high temperature flow field as a function of the phase of the pulsing methanol fire. The results provide insight into the dynamic character of turbulent pool fires. The data will be useful for model validation.

Citation

Technical Note (NIST TN) - 2031

Report Number

2031

NIST Pub Series

Technical Note (NIST TN)

Pub Type

NIST Pubs

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DOI Link

Keywords

field measurements, methanol, pool fires, pyrometry, temperature

Citation

Wang, Z. , Tam, A. , Lee, K. and Hamins, A. (2018), Temperature Field Measurements using Thin Filament Pyrometry in a Medium-Scale Methanol Pool Fire, Technical Note (NIST TN), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.TN.2031 (Accessed April 23, 2024)