Experimental studies of magnetic confinement effects on premixed methane flames using PIV and thermal diagnostics

This study investigates the influence of magnetic fields on the structure, temperature, and flow field velocity distribution of premixed CH₄ flames under varying magnetic field strengths using electromagnets and equivalence ratios (φ = 1.0, 1.4, and 2.0). Experiments were performed using Particle Image Velocimetry (PIV), flame photography, and temperature measurements to evaluate flame height, width, profile area, distortion index, and internal velocity distribution changes. The results indicate that increasing magnetic field strength compresses the flame, reducing flame height, width, and profile area while decreasing the flame distortion index, which signifies improved flame stability. Temperature measurements indicate that the magnetic field enhances combustion efficiency by accelerating oxygen mixing/diffusion into the combustion zone, particularly in the main combustion region. Quantitatively, a flame height reduction of up to 8.42 % and a temperature rise of approximately 298 K were observed under fuel-rich conditions (φ = 2.0). Velocity distributions reveal a significant increase in centerline flame velocity magnitudes under stronger magnetic fields due to the enhanced mixing of paramagnetic oxygen and the resulting magnetohydrodynamic (MHD) effects, contributing to improving combustion efficiency. Here, flame velocity refers to the internal flow field velocity extracted from PIV measurements, not to the laminar burning velocity. The relative standard deviation (RSD) of flame parameters remained under 5 %, demonstrating high measurement repeatability. This study is motivated by the need for enhanced combustion control through magnetic field application by electromagnets, and the findings confirm that magnetic fields significantly improve flame compactness, thermal efficiency, and stability by modifying oxygen transport and flame flow dynamics. These findings demonstrate that electromagnetic fields influence flame characteristics through improved oxygen mixing and combustion stabilization.