Numerical Simulation of a Low Emissions Gas Turbine Combustor Using KIVA-II Part II: Quick-Quench/Lean-Combustion Zones Analysis

SUMMARY This is the second part of the numerical investigation on a low emissions staged turbine combustor (STC) using a modified version of the KIVA-II code. The main focus of this study is the numerical analysis of the reacting fluid flow and heat transfer inside the quick-quench/lean-combustion (QQ/LC) zones. In the QQ zone, cool dilution air was injected into the hot mixture through eight 45° inclined slots with a momentum flux ratio of 60. The slot aspect ratio was 6 and the jet-to-mainstream mass flow rate ratio was 3. The inlet conditions of the QQ zone were obtained from the results of rich combustion zone analysis described in part I. A tension spline interpolation scheme was then used to interpolate the necessary information needed at the inlet. Conditions at the slot opening (dilution jet) were chosen closely related to those encountered in advanced combustion systems. The Grid system needed for the numerical solutions was generated by a transfinite interpolation scheme. KIVA-II was further modified for the current study. Preliminary results illustrate some of the major features of the flow and temperature fields inside the QQ/LC zones. Formation of the co-and counter-rotating bulk flow and the sandwiched-ring-shape temperature field, typical of the confined inclined jet-in-cross flow, can be seen clearly and is consistent with experimental observations. The calculations of the mass-weighted standard deviation and the pattern factor of temperature revealed that the mixing performance of the STC combustor is very promising. The temperature of the fluid leaving the LC zone is very uniform. Prediction of the NOx emission index showed that there was no excessive thermal NOx produced in the QQ/LC zones for the case studied. From the results obtained so far, it appears that the modified KIVA-II code can be used to guide the low emission combustion experiments.