Numerical Simulation Of Compressor Performance Deterioration On The Influence Of Combustor Emission

Marine gas turbines always run in humid and salt spray environment, which aggravates the corrosion of compressor and causes the compressor performance recession. Compressor performance recession will inevitably lead to the change of combustion conditions in combustion chamber, and directly affect the gas turbine emissions. What changes will happen in combustion chamber when the compressor performance deteriorates is the significance of this study.In this paper, a low pressure compressor of multi-stage axial flow compressor and combustion chamber are researched. Effects of tip clearance on compressor efficiency, compression ratio, and the mass flow rate and outlet temperature are studied, while the influence of compressor performance recession on outlet physical parameters and chemical composition of combustion chamber are also gained. The main research of this paper is shown as following:1. Numerical simulation of the compressor is carried on by NUMECA under the conditions of six different speed and five different tip clearances. The six different speed contains7285rpm,7000rpm,6500rpm which corresponds to zero stop point model and6000rpm,5500rpm,5000rpm which corresponds to negative stop point model. The five different tip clearances are set to original design gap,1.5%,2%,2.5%and3%of the blade height. Basing on the numerical simulation results, the changes of compressor performance when tip clearance is extended are obtained. When compressor blade tip clearance increases, the compressor isentropic efficiency, the pressure ratio, the mass flow rate have a recession, and the mass flow rate have the most serious recession, while the compressor outlet temperature increases. When compressor blade tip clearance increases, the stage isentropic efficiency and the stage pressure ratio have a recession excepted parts of stages, while the stage temperature ratio increases, the change amount of compressor each performance parameter is different at different rotation speed. There is a significant impact on the first three stages of the compressor when tip clearance increases. When compressor blade tip clearance increases, along the blade height direction the pressure ratio and the isentropic efficiency are failed. As the tip clearance increases, the amount of recession of pressure ratio and isentropic efficiency are greater.2. Using the low pressure compressor outlet condition and the high pressure compressor characteristic curves, the high pressure compressor outlet condition is obtained, which is the inlet condition of the combustion chamber.3. When the compressor operates on the same rotation speed, the flow field of gas turbine combustion chamber is simulated using FLUENT. Realizable k-ε turbulence model, rapid chemical reaction system and simple probability density function (PDF) combustion model under the conditions of chemical equilibrium, and SIMPLE algorithm are used. The combustor outlet speed and the temperature pattern factor decrease with the increase of compressor outlet pressure. The combustor outlet temperature and the maximum outlet temperature increase with the compressor outlet pressure increase.4. When compressor performance deteriorates, the flow field of gas turbine combustion chamber is simulated using FLUENT. With the increase of the compressor blade tip clearance, the combustor outlet speed, the mass fraction of O2and N2are reduced; While the combustor outlet temperature, the maximum outlet temperature, the temperature pattern factor, the average mixture fraction, the mass fraction of CO, the mass fraction of CO2and the mass fraction of NO increase.