Hydrogen-enriched flames in a novel miniature double-layer disc-combustor with annular step and Swiss-roll preheated channel

摘要

A novel miniature double-layer disc-combustor with annular step and Swiss-roll preheated channel is de-veloped for the first time, which can act as a heater or the miniature heat source for a miniature power source. The premixed flame dynamics of 80%H2-20%CH4-air are experimentally studied in this combus-tor. The results show that the flame blow-off limit increases first and then sharply decreases with the decreased value of Reynolds number Re . It is the first time to find the anomalous blow-off phenomenon in the radial channel. The analysis indicates that the decreases of flow recirculation effect, heat recircu-lation effect, and preferential diffusion effect lead to the decreased blow-off limit with the decreased Re value. The flames can remain stable in a wide operating range. At the large Re value, the flame diameter obviously increases with the decreased value of equivalence ratio phi, and the flame anchors right behind the annular step at the small phi value. At the small Re value, the flames all reside around the exit of Swiss-roll preheated channel, which results in the small flame diameters. The magnitude of the upper wall temperature decreases with the decreased phi value. At large phi values, the distribution characteristics of high temperature zone of the upper wall are similar, and the peak value of temperature appears at its center. At small phi values, the peak value and magnitude of wall temperature are both larger for a bigger Re value, and the location of peak value slightly shifts upstream with the decreased Re value. The upper wall temperature of the combustor can be expediently managed by adjusting the operating conditions. In addition, the mean temperature of the upper wall and heat transferred from the upper wall to the en-vironment almost linearly decrease with the decreased Re value. The present study expands our insights into the flame dynamics in the radial channel.(c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.