Precise surface temperature measurements at kHz-rates using phosphor thermometry to study flame-wall interactions in narrow passages

TL;DR

This study employs high-speed phosphor thermometry with ScVO4:Bi3+ to achieve precise, time-resolved surface temperature measurements at 5 kHz, enabling detailed analysis of flame-wall interactions and heat transfer in narrow passages.

Contribution

It introduces the use of ScVO4:Bi3+ for high-precision, high-speed surface temperature measurements, benchmarking it against common phosphors, and applies it to study transient heat loss and flame dynamics in crevice geometries.

Findings

ScVO4:Bi3+ offers higher luminescence and sensitivity than Gd3Ga5O12:Cr,Ce.

The method captures transient temperature transients related to flame behavior.

Wall heat flux and quenching distances are quantified for different flame states.

Abstract

The thermographic phosphor ScVO4:Bi3+ is used to obtain time-resolved surface temperature measurements with sub-oC precision at 5 kHz. Measurements are used to study transient heat loss and flame-wall interactions (FWI) within a dedicated narrow two-wall passage (crevice) in an optically accessible fixed volume chamber. This passage emulates a crevice relevant in many technical environments, where FWI is less understood due to lack of detailed measurements. Chemiluminescence (CH*) imaging is performed simultaneously with phosphor thermometry to resolve how the spatiotemporal flame features influence the local surface temperature. ScVO4:Bi3+ is benchmarked against Gd3Ga5O12:Cr,Ce, a common phosphor used at low-kHz rates in FWI environments. ScVO4:Bi3+ is shown to offer higher luminescence signal levels and temperature sensitivity as well as negligible cross dependence on the excitation laser fluence, improving the precision and repeatability of the wall temperature measurement. ScVO4:Bi3+ is further used to resolve transient heat loss for variations in crevice spacing and uniquely capture temperature transients associated with flame dynamics. Taking advantage of these precise surface temperature measurements the wall heat flux is calculated with crevice spacing of 1.2 mm, where flame extinction is prevalent. Wall heat flux and estimated quenching distance are reported for flames that actively burn or extinguish at the measurement location.