In this work the temperature field in a gas turbine combustion chamber is investigated through numerical computations. The combustion chamber under study is part of a 70 MW gas turbine from an operating combined cycle power plant. The simulation of combustion and flow dynamics is fully 3-dimensional. It addresses complex turbulence structure and temperature distribution inside the combustion chamber. The swirling effect is taken into account using a detailed gas-fuel-air mixing swirler. The combustion was simulated with proper gas-fuel-air flow ratio assuming stoichiometric equilibrium conditions. Based on previous results, pressure imbalance conditions of air flow between primary and secondary inlets is used to perturb the temperature distribution. In this work, a periodic function was used to produce pressure variation in the air flow, which in turn alter the temperature field and turbulence structures. First, characteristic temperature and pressure fields were obtained using steady state boundary conditions. The steady state solutions were perturbed using a periodic boundary condition (6 kPa per short periods of time) resulting in different results. The results are discussed and confirm previous 2-dimesional computations where excessive heating in regions other than the combustion chamber core occurred. The investigation is aimed to explain why overheating occurs, since it causes burning out of pipe materials, producing permanent damage to auxiliary cross flame pipes.

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