Dome Design And Performance Analysis Of Radially-staged Can Annular Low Emissions Combustor

With the increasingly prominent environmental pollution problems,the limited standards for pollutant emissions are becoming stricter and that makes low emissions to be the essential characteristic of modern gas turbines.But the higher pressure ratio and turbine inlet temperature further promotes the formation of NOx and other pollutants with the development of high-performance gas turbine technology,which makes it more difficult for low emissions gas turbine design.Lots of excellent low emissions technologies have arisen in this context.Lean direct injection(LDI)as one of the advanced low emissions technologies has great potential for low emissions(especially at high temperature and pressure conditons)and whose NOx emissions closes to LPP combustion technology.But it can eliminate the flashback and self-ignition of premixed combustion,so it has broad application prospects.Based on multipoint LDI combustion technology,a variety of methods such as experience formula for structure design,one dimensional chemical network model(CRN)for air flow distribution and optimization,three dimensional numerical simulation for periodic simplification and full size research and validation are used to retrofit a certain combustor model.Finally,it is retrofitted to be a radially-staged low emissions combustor and the design process for radially-staged low emissions combustor is summarized.To solve these problems,the following research activities are investigated:(1)The methods such as experience formula and one dimensional chemical network model(CRN)are used to design and optimize the structural parameters for swirler,venturi and air flow distribution of the single point LDI combustor.The final air flow rate for swirler is confirmed to be 70% and so the air flow rate for cooling is confirmed to be 30%.(2)The one-dimensional air flow distribution optimization results are used as the boundary conditions and the single point LDI combustor is studied.The effects of structural parameters such as venturi divergence,contract angle and throat diameter on combustion performance are investigated.The structure of single point LDI combustor is optimized so as to attain a good LDI structure with excellent performance.(3)Based on the optimization results of single point LDI combustor,the multipoint LDI combustor is established in a simplified flame tube for array composite.The effects of multipoint LDI combustor such as dome array configuration,swirlers rotation and distance between nozzles on combustion performance are investigated.Two configurations with excellent combustion performance are confirmed and related structural parameters as also.(4)Two full size computational models with good performance are established and comparative study between the two configurations under 100% and 30% conditions is conducted.Results show that the configuration with counter-rotation has the best combustion performance.The NOx emissions under 100% condition is 128.22 ppm with 67.95% reduction of prototype combustor.The outlet temperature distribution factor(OTDF)is 14.35% and total pressure loss is 4.76%;The center pilot and counter-rotation main2 stages are used to attain better combustion performance under 30% condition with 45.10 ppm NOx emissions,28.09% OTDF and 4.99% total pressure loss.Every indicator meets the design requirements.(5)Considering the bad performance of OTDF under the idle conditon,the venturi of center pilot is modified.With the outlet diameter of venturi divergent section increases to 59 mm,the OTDF fall from 55.16% to 28.40%,which meets the design requirements.(6)The fuel staging strategy under different conditions is investigated.The pilot circuit supplies fuel to the pilot injectors at the idle condition lonely and keeps working at other conditions.All fuel is shifted to pilot and main2 stage at 30%-70% conditions.When the condition is higher than 70%,the main1 begins to supply the fuel.By the method of pilot local rich fuel and main2 local lean fuel,it can attain better NOx emissions performance.The design process for radially-staged low emissions combustor is also summarized.