Numerical Prediction Technology Research Of Combustion Flowfleld Of Liquid Fuel

The working of combustor directly determines the turbine inlet parameters andperformance parameters of the whole unit, so the design of combustor is particularlyimportant. However, the traditional combustor is mainly designed by using empirical orhalf-empirical formula method. Not only the research cycle is very long, but also is verycomplicated. So this paper discusses a new method for designing the combustor that isburning liquid fuel, which provides a reference valve to combustor’s designing in the future.The paper first use Chemkin to finish one-dimensional calculation of combustor, usingFluent to finish three-dimensional periodic expansion design, and on this basis thethree-dimensional full size checking was finished. In the end, Chemkin was used to predictthe NOx emission of combustor outlet. When using Fluent for calculation of the combustor,Realizablek εturbulence model and a simplified PDF combustion model were adoptedhere. Particle trajectory model is used to describe the moving track and variation process ofliquid oil droplets. The upwind scheme was used to discrete the equations. Standard wallfunction was used to solve the wall problem. The SIMPLE algorithm method is applied tosolve the equations.This paper use the Chemkin software for one-dimensional design,firstly build the initialchemical reactor network of the combustion chamber to determine the optimal air ratio,andthen micro-element method is employed to calculate the effective length at each combustionchamber characteristics region.In the three-dimensional periodic expansion combustionchamber design, the one-dimensional feature length parameter is obtained according to theChemkin software,and the full sized backflow ring combustion is periodicly simplified,onlychoose a flame tube to simulate under the permise, then1/10simulation,and finally get theneeded data of the full sized combustion chamber design.Finally according to the calculatedcombustion characteristic parameters,build the full sized chamber model and make anumerical simulation of three-dimensional flow field in the combustor.Then with the Fluenttechnology, based on flame tube wall insulation calculation situation. Finally the Chemkinsoftware is employed to build the detailed chemical reactor network of the combustor fluidregion, and the pollutant emission NOx from the combustor is calculated. Meanwhile,different turbulence models are compared in this paper and the difference among these modelsis obtained. The whole research in this paper indicates that the two-stage swirler angles are both45degree and using reverse swirl angle is better; when area ratio of the two-stage swirler is1.49:1, the recirculation zone boundary is smaller and shorter. Howerver, the combuster worksbetter. In the comparision of the turbulent combustion model, it has been found that thetemperature of flow field are overestimated by using both ED and EDC model and it issimulated resonably by using PDF and SFM model. But the reaction mechanism of SFMmodel is too complicate, it is all used PDF model to simulate the combustion. It can beacknowledged that this new way of designing is variable and valuable to the future work ofcombustor designing.