Laser Welding of Structural Aluminium

Abstract

Hydroxyl radical decay rates were measured in laminar atmospheric pressure CHsub 4/Osub 2-Nsub 2-Ar flames (phi = 0.85-1.1) with and without the addition of potassium (mole fractions up to 3.6 times 10sup -4). Flames were stabilized on a flat-flame burner shrouded by nitrogen. OH number density profiles were determined from laser absorption at 309.28 nm A-X, O-O Qsub 2(6). Potassium profiles were obtained from laser absorption on the 404.53-nm transition. Addition of potassium was observed to accelerate the OH decay rate, with the additive influence being most pronounced at higher equivalence ratios. The influence of K was nonlinear, and increasing seeding levels produced progressively less acceleration of the OH decay rate. (23 Refs.) (Edited author abstract)