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

Published: November 29, 2018

Author(s)

Zhigang Wang, Wai Cheong Tam, Ki Yong Lee, Anthony P. 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

Keywords

field measurements, methanol, pool fires, pyrometry, temperature
Created November 29, 2018, Updated November 29, 2018