Numerical Prediction Technology Study Of Gas Fuel Combusting Flow Field In Combustor

Gas turbine is a common power device for ships,whose performance has significantinfluence on the performance parameters of the whoel power unit.It is of great importance forcombustor design to be reasonable.Traditional comustor design relies on empirical and hemiempirical formula,which takes a long research period.To address the disadvantages above,anew and fast approach of combustor design is proposed in this paper.Methane is fuel in this paper. One-dimension characteristic length of the combustor isobtained utilizing Chemkin software and the microelement method.Three-dimension periodicextension design is achieved by Fluent software,on which a full-scale check is conducted.The outlet NOx discharge of the final design of optimum combustor is analyzed by Chemkinsoftware.During three-dimensional simulation, Realizable k εdual formula turbulent modeland PDF combution model are adapted;the governing equation is discretized using an upwinddifference scheme,the wall is treated with standard wall function method and the discretequation is solved using SIMPLE algorithm.During the process of conducting one-dimensional optimal design for organization formof the combustion flow field, firstly primary chemical reactor network is used to get the bestair proportion, then, the effective reactive length of flame tube is obtained through amicroelement method, which is a kind of one-dimension length verification method forcombustor.The whole data needed for full-scale design of combustor is obtained and combustormodel is established with the feature size under following conditions: parameters ofone-dimension length are obtained by utilization of CHEMKIN; the cyclic-symmetricsimplification of the full-scale return-flow and can-annular combustion chamber; one tenth ofthe flame tube is simulated while using one tube to simulate as prerequisite. The combustioncharacteristics are analyzed by using FLUENT under the adiabatic computing case of the wallof flame tube. Detailed chemical reactor network is established with the flow field ofcombustor which finally designed by author and the magnitude of the pollutant emission isobtained simultaneously. Additionally, Analysis and comparison of different turbulencemodels are also conducted and advantage and disadvantage of each are demonstrated in thispaper. The calculation results show that the distribution of each parameters and theorganisation of combustion field in the combustor where methane burned is relativelyreasonable based on the calculation program which use Chemkin to carry on the1D optimaldesign and CFD method to calibrate the3D design. According to the compared results of fourdifferent turbulent models which used during simulation and considering the tempratureunevennus of outlet field, maximum temprature and the cooling performance of head andwall，the realiable turbulent model is found to be the best one. This design program canbasiclly meet all requirements and be considered as viable.