Numerical Simulation Of Nature Gas Combustion In The Micro-gas Turbine Combustor

In the21st century, the energy demand is greatly ascend in many industries.Energy utilization has developed by agile diversity. Micro-gas turbine is the coreof the Combined Cooling Heatingand Power system, it can realize efficient useof the energy on the base of gradient utilizationof energy. Currently, CombinedCooling Heatingand Power system is gradually becoming the mainstream of thedevelopment of new energy systems.As the core of the Combined CoolingHeatingand Power system, micro-gas turbine’s researches had got substantialsupports from the National Science and Technology department of country in therecent ten years. Combustor is one of the most important parts in micro-gasturbine, its various performance are the important indicators of micro gas turbine.This paper studies and puts forward the structure design of micro-gas turbinecombustion and uses the method of numerical simulation to study its variousperformances. By the calculation results of numerical simulation, thepreliminary design scheme was optimized and the combustor structure wasimproved to fulfill its performance requirement. Main Contents of the paper asfollows：Firstly, according to the related data of gas turbine design,the structure ofcombustor which uses Dry Low NO_xto reduce the area of high temperature inflame tube remarkably was raised,this structure can reduce the wall temperatureof the flame tube and bring down the NO_xemissions.Secondly, the geometry model of combustor was built by Solidworks, andthe fullsize numerical simulations were accomplished by Ansys.Due to the relatively complexities of combustor structure that has multi-stage hydrocyclones, it is difficult to generate geometry mesh. So the geometrymodel was scattered into many parts by generating structured hexahedron mesh,and the meshes were pieced together by Ansys.Meanwhile it is convenient tochange unreasonable combustor structure at the simulation processes.Finally, the various properties of micro-gas turbine combustor were studied by the method of numerical method. Results displayed that the total pressurerecovery coefficient of combustor reached92.5%, and NO_xemission was15.16ppm（15%O2） at the rated conditions. But the flow distribution of thecombustor had some deviations. According to the results, the influences ofparameters on the structures were researched, and the combustor structureswere optimized by the following ways:(1) By changing the distributions of thefuel proportion,the fuel ratio’s influence on the formation of NO_xwereresearched.(2)To esure the accuracy of the air-fuel ratio of combustor, the areaof air inlets were adjusted to optimize the flow distributions.(3) The researchresults showed that air inlet temperature can influence the total pressurerecovery coefficient, and the roughly corresponding relation between velocityand total pressure recovery coefficient had been affirmed. The total pressurerecovery coefficient was increased by reducing the air velocity and changing thestructure sizes of combustor.(4)The high temperature fields of flame tube werereduceded by changing the structures of combustor and flame tube.