Combustion Performance Investigation Of A Combustor With Different Dual-stage Swirlers

In this paper, lean blowout characteristic and combustion performance experiments in a model combustion chamber with different dual-stage swirlers(including 11 kinds of double radial swirlers, 5 kinds of oblique radial swirlers and 10 kinds of double axial swirlers) were investigated seperately. And relative numerical simulations of combustion performance about the three kinds of dual-stage swirler combustors were also studied, numerical results were compared with experimental results.Firstly, the system for the combustion experiment at high temperature and high pressure conditions is designed and manufactured, the system can conveniently adjust the inlet pressure, inlet temperature and inlet mass flow rate of the combustor. And it can also measure the distributions of combustor outlet temperature, pressure and pollutant.Secondly, the lean blowout characteristics of the model combustor are investigated. At the experiment process, the inlet air mass flow rate of model combustor is 500g/s and the pressure is 5bar. At the same time, the fuel mass flow is reduced step by step, until the the flame in the model combustor flameouts, the lean blowout fuel air ratio(LBFAR) is obtained. During the flameout of combustor, the performance parameters, such as the temperature of combustor outlet, temperature rise of combustor, pressure loss of combustor and gas compositions of combustor outlet, are obtained. The following conclusions can be obtained: 1) With the decrease of the fuel-air ratio, the outlet temperature and the temperature rise of the modle combustor gradually decrease. At the LBFAR, the outlet temperature and the temperature rise have a sharp jump. 2) With the decrease of the fuel-air ratio, the pressure loss of combustor gradually increases, but the rise rate is very small. 3) With the decrease of fuel-air ratio, the concentration of CO2 at the outlet of combustor decreases, and the concentration of O2 increases. In order to verify the effects of cooling air mass flow rates on the LBFAR of model combustor, for the same dual-stage swirler, the experiments of lean blowout characteristics with different cooling air mass flow rates are completed. The experimental results show that the cooling air mass flow rates have no effect on the LBFAR. Finally, the LBFAR for the 26 kinds of dual-stage swirlers are obtained, and the difference is very small and the LBFAR is around 0.007.Thirdly, when the inlet air mass flow rate is 500g/s, the inlet pressure is 5bar and the fuel mass flow rate is 8.15g/s, the combustion performance experiments of the model combustof with different dual-stage swirlers(including 11 kinds of double radial swirlers, 5 kinds of oblique radial swirlers and 10 kinds of double axial swirlers) are completed seperately. During the experiment process, the CO concentration at the outlet of model combustor is very small. In order to verify the influences of different inlet temperatures and inlet pressures on combustion performance, combustion experiments with different inlet temperatures and pressures are carried out seperately. The experimental results show that: 1) With the increase of inlet temperature or inlet pressure, the combustion efficiency increases gradually. But, when the inlet temperature is above 600 K or the inlet pressure is above 4bar, the combustion efficiency with different dual-stage swirlers is almost to 100%, therefore, the increase ratio is very small. 2) With the increase of inlet temperature, the pressure loss increases. For different dual-stage swirlers, the change ruler is same, but there is a different value for different dual-stage swirlers. 3) With the increase of inlet temperature or pressure, the CO concentration decreases, but the NO concentration increases. 4) The relationships of CO and NO concentration with the inlet temperature are seperately. 5) The relationships of CO and NO concentration with the inlet pressure are seperately. And these relationships can give some advances for the next combustion performance prediction. 6) The outlet temperature, temperature rise, pressure loss and gas component concentrations have some small differences for these 26 dual-stage swirlers, but the differences are small.Finally, the combustion performance of the model combustor with different dual-stage swirlers are numerically simulated. During the numerical simulation, the Finite-Rate/Eddy-Dissipation model is used to model the chemical reaction rate. The numerical results are compared with the experimental results. It shows that: 1) There are some differences for the recirculation zone and the high temperature distribution of different dual-stage swirlers. 2) There is some small difference between the numerical results and experimental results for the temperature distribution. 3) The mathematics models and numerical methods can be used to predict the combustion performance of dual-stage swirl combustor.