The Effects of Pressure on Gas Turbine Combustor Performance: An Investigation via Numerical Simulation

Abstract

Performance tests of a gas turbine combustor are usually conducted at atmospheric or medium pressure which is quite different from its real operating condition. The effects of pressure on the performance of a gas turbine combustor for burning medium-heating-value syngas are researched by numerical simulation in this paper. The geometry of the combustor is modeled by coupling all its components including nozzle, combustor liner and sealant tube. In the simulation a laminar flamelet model and P-1 radiation model are adopted. The numerical results show that at the same fuel and air inlet temperature and the same equivalence ratio, the operation pressure has less effect on the flow fields, but its effect on the temperature distribution is obvious. Both the highest temperature in the combustor and the outlet temperature increase with increasing operating pressure because of the weakening of the dissociation of the H2O, CO2 and so on. Moreover, as pressure increases, the concentration of H2O and CO2 in the combustor increase, and so to does the absorption coefficient and the emissivity of gas inside the liner. As a result, the radiation heat transfer between the gas and the combustion liner wall is enhanced, and the wall temperature of the liner increases. The NOx emissions of the combustor are also distinctly higher at high pressure than at low pressure.