To develop efficient combustors under various operating conditions, a deeper understanding of the effects of swirl flow mechanisms on gas turbine combustion is essential. The double swirl flow arrangement has an advantage over the single swirl flow by proving better mixing and flame anchoring due to the increased shearing action between the two swirl flows. The flow field of the open-type, double swirler burner at various Reynolds numbers is analyzed using the 2D particle image velocimetry (PIV) technique. The spatial distribution of OH* and CH* chemiluminescence is analyzed for one premixed (ϕ = 0.75) and three stratified LPG/air flames. Medium swirlers are used for velocity measurements, while two different axial swirlers, defined as low and medium swirlers with geometric swirl numbers 0.5 and 0.8, respectively, are used for chemiluminescence studies. The analysis of non-reacting flow field results shows that the increase in the Reynolds number of outer swirl increases the radial component of the velocity; thus, the swirl flow spreads in the radial direction. As a result, turbulence parameters such as Reynolds stress and turbulence intensity are also dominant in the radial direction. As a consequence of this phenomenon, in the worst case, the spread of the flame front and further local quenching could occur. In comparison, the increase in internal swirl flow increases the axial components of the velocity and the flow field becomes axially elongated. The inner recirculation zone shifts downstream of the flow field, suggesting that the reaction zone could be moved to the downstream under the reacting condition. The acquired OH*/CH* chemiluminescence signals indicate that the premixed LPG flames are elongated while the upstream stratified mixture conditions lead to more compact flames that are appropriate for gas turbine applications. Nonetheless, for medium swirler cases, OH*/CH* chemiluminescence is much more compact in form than low swirl. Intensity variation is independent of the flame strain of propane; thus, the equivalence ratio calculated from the OH*/CH* intensity ratio has helped to understand the interaction between flame and turbulence at various operating conditions. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.