In strong swirl flame, to know the effects of equivalence ratio, swirl degree, and quarl half angle on the Nitric Oxide (NO) formation, measurements were made: temperature by water-cooled Pt-Pt/13% Rh thermocouple, concentrations of stable gases by gas chromatograph, and Nitric Oxide concentration by chemiluminescent NO analyzer.
Results are as follows;
1) Nitric Oxide is most likely formed in the narrow region where the gas temperature is maximum.
2) Nitric Oxide that formed in the primary reaction zone is strongly dependent on temperature.
3) For low Nitric Oxide emission flame, optimal conditions of equivalence ration and swirl degree can be explained by flame structure influenced by equivalence ratio and swirl degree.
4) For flame stability, it is appropriate that the quarl half angle is near 20℃. $^{(10), (12)}$ But for low Nitric Oxide emission flame, smaller value of quarl half angle is found more appropriate.
