Research On The Dome Structure Of Model Combustor With Conical Swirler

Achieving low emissions is one of the main development directions of gas turbine.At present,dry low NOx combustion technology is widely used in low emission gas turbine combustors.The lean premixed combustion used in low-NOx combustors can easily lead to combustion instability,especially in low operating conditions,even a sudden flameout may occur,which may cause equipment failure in severe cases.In this paper,the conical swirler model combustor using lean premixed combustion technology is taken as the research object,and related experimental and numerical simulation studies are carried out in order to explore the flow field characteristics and combustion characteristics of the combustor.According to the problems found in the experimental study,the structure of the conical swirler was improved and optimized,and the effect of the improvement was verified by the experiment.At the same time,the influence of key operating parameters on combustion stability is studied experimentally.The research results can provide some reference and basis for the design and development of low-pollution gas turbine combustors.The main research contents and conclusions of this study are as follows:(1)In this paper,we firstly designed and manufactured a conical swirler model combustor,and then carried out a series of combustion experiments.The first-hand experimental data of the combustion characteristics of this type combustor were obtained.Numerical simulation was performed,and the characteristics of typical flow field,recirculation zone and temperature field were obtained.At the same time,the effect of the center gas in the conical swirler was studied by combining experiments and numerical simulations.The results show that the arrangement of the center gas plays an important role in the combustion stability and the structure of the recirculation zone.Proper proportion of center gas distribution ratio can significantly improve the lean blowout performance of combustor,and properly optimize the structure of the recirculation zone,so as to avoid the flame too deep into the cone.Finally,the effects of gas distribution ratio on lean performance and dynamic pressure characteristics of the combustion chamber were studied in detail.These work above provided reference data and support for further research.(2)In order to further improve the combustion stability of the combustor under low operating conditions,a method of arranging a center body of a specific geometry at the head of the conical swirler is proposed.Through numerical simulation and experiments,a variety of center body structures are compared and analyzed to obtain the center body geometric parameters with better LBO performance and pulsating pressure characteristics,and the conclusions are as follows: the axial length of the center body is 50% of the axial reference size,the diameter is 37% of the radial reference size,the gas injection angle is 30 °,and the gas injection hole is 8 small holes with a diameter of 0.8 mm.(3)In order to reduce the pressure fluctuation in the combustor,this paper proposes to arrange a lateral jet at the head of the conical swirler model combustor to regulate the pulsating pressure intensity in the combustor.Through experimental comparison,the effects of two schemes of injection of combustible gas and noncombustible gas are analyzed.It is found that the lateral injection of non-combustible gas is more effective,which provides a reference for the research on the active control technology of the conical swirler combustor.(4)Experimental study of the conical swirler model combustor with the center body after the structure optimization was performed.The combustion characteristics were revealed by measuring and analyzing the pollutant emission,temperature distribution and combustion efficiency of the typical experimental points;At the same time,experimental work on the effects of parameters such as equivalent ratio,gas distribution ratio,and inlet air temperature on the pulsating pressure characteristics of the combustor was carried out.The influence of these parameters on the combustion stability of the combustor was summarized,which provides a more detailed reference for the improvement of the combustion stability of the conical swirler combustor.