Structure Optimization Design For Short Dump Diffuser In Gas Turbine Combustor

Dump diffuser regarded as a kind of the more common diffuser,which has some significant advantages of simple structure,small length and quality,stable internal flow and insensitive to import distortion,is widely accepted and used in the engineering.However,the performances of engine are affected significantly because of bigger pressure loss of dump diffuser.Currently,the researches for the aspect have been not made so much relatively,as a result of the former statement,the purpose is aiming at improving disadvantages of great pressure loss of dump diffuser.Research of numerical calculation is carried out for the characteristics of internal turbulence flow of three-dimensional dump diffuser.Besides,influence law of the effect of the various structural parameters of dump diffuser on the performance of the diffuser and the flow in the internal flow field is analyzed and the effect of the dump diffuser on the combustion performance of the combustion chamber is studied.In the parameter scope,in the case of constant length and width of diffuser,with the increase of the divergent Angle,the static pressure rise in value and diffusion efficiency of the diffuser are enhanced,the pressure loss coefficient is reduced to some extent.With the increase of the height of front diffuser,the static pressure rise in value and diffusion efficiency of the diffuser are enhanced,the pressure loss coefficient is reduced to some extent.At the same time,flow characters of internal flow field and performances of diffuser are influenced by changing sudden expansion spacing of the diffuser.Besides,the performances of modified diffuser combining three structure parameters are better than only adjusting structure parameters,namely the comprehensive properties of diffuser is improved by means of optimization method of combining three structure parameters.Based on the above conclusion,structure size that improves the comprehensive performance of diffuser obviously can be found.Under the condition of variable working condition,as the increase of the mass flow of inlet air,the diffusion efficiency of modified diffuser is gradually enhanced and the pressure loss coefficient is gradually decreased by changing the initial conditions.As the increase of the turbulence intensity of inlet air,the diffusion efficiency of modified diffuser is increased at first then decreased and the pressure loss coefficient is decreased at first then increased,Through the simulation of combustion characteristics of combustion chamber of the modified dump diffuser,it can be concluded that the introduction of the structure of the modified dump diffuser is beneficial to the combustion in the combustion chamber,improving the most unevenness of the temperature in the outlet section,enhancing the combustion efficiency of the combustion chamber and reducing the emissions of pollutants.Through comparative analysis of the performance of the different structural parameters of A under the different initial conditions,design rule of the type of diffuser can be concluded,which is a reference to engineering design.