Introduction

Gas turbines are widely used in power generation, considering the efficiency, reliability and stability of the turbines during operation \citep{Kwon_2019}. The gas turbine works on the principle of Brayton cycle, where compressed air is combined with fuel and burnt under constant pressure, causing the resulting hot gas to expand across the turbine and perform work \citep{Huitenga_2014}. The power generation, however, emits NOx and COx gasses, which pose a challenging task to achieve the authority’s permitted pollution limit \citep{Suman_2018,Rigo_Mariani_2019}. The need for an environmental friendly solution to the challenge leads to the introduction of Dry-Low Emission (DLE) gas turbine \citep{Hazel_2014,Nemitallah_2018}. As shown in Fig. \ref{fig:1}, DLE gas turbine performs a Lean Pre-mixed (LPM) combustion to ensure COx and NOx reduction \citep{Abdelhafez_2018}. LPM technology diffuses high content of atmospheric nitrogen before being delivered to the combustion chamber \citep{Serbin_2011} to prevent “local hotspot”. Through controlling the fuel opening of a pilot gas fuel valve and changing the amount of air supplied to the combustor, the optimum temperature for lower emission is achieved \citep{Massey_2019}.