Research On Organization Method Of Combustion Flowfield Characteristics In Combustor

Gas turbines are widely equipped in warships. Combustor is a key part of gas turbine, whose performance is directly linking to its lifespan and power output. The structural design of the combustor is limited to experience and semi-empirical formula. This method is complicated, requiring a long design period, which obstruct its development seriously. According to this situation, this paper introduces a method for design the flow field of combustor from one-dimensional manipulation to three-dimensional numerical simulation, and then verificates the feasibility of this method by correcting the flow field of a certain type gas turbine combustor, which provides a reference to gas turbine's development.Based on a certain type of gas turbine combustor, this thesis optimizes its flow field by using one-dimensional method without changing the structure of head and gas collector. With CFD technology, a numerical simulation was used for calculation of the combustor, Realizable k-εturbulence model, a simplified PDF combustion model were adopted here. Second order upwind scheme was used to discrete the equations. Standard wall function was used to solve the wall problem. SIMPLEC algorithm method is applied to solve the equations.In the one-dimensional optimization of the combustion chamber flowfield, the one-dimensional length checking method of combustor is brought in according to the CHEMKIN calculation features and operating characteristics of gas turbine combustor, which is called micro-element method. In this thesis we construct two chemical reactors characteristics network of the combustor. The micro-element method is employed to calculate the effective length at each combustion chamber characteristics region. The effective length ratio of each region is determined by the combustion chamber region length. Make a deep analysis of the characters of network 2 with CHEMKIN. Here we make an analysis of the variation of combustor flow field through the way that changing the air ratio in flame tube. Using the minimum NOx emissions principle determines the optimum air ratio of combustion chamber. On this basis, we make a caculation of chamber feature regions length with the air ratio.A new combustor model was built according to the certain parameters. We made a numerical simulation of three-dimensional flow field in the combustor with the CFD technology, based on flame tube wall insulation and thermal conductivity calculation situation. A feasibility analysis of this combustor was made from the effcience, temperature, velocity and flame length of reacting flow field. Using the FLUENT software and chemical reactor network, the pollutant emission from the combustion chamber is calculated. Referring to the prototype combustor, we get the ultimate pollutants emission. The result shows that this kind of combustor has a significant recirculation zone, which is conducive to the stability of the flame spread. The maximum inhomogeneity of outlet temperature field, flame length and emissions are acceptable. The wall temperature is a little high, but still up to the standard, which meets the design requirements.At last, the summary of the calculation method was made comprehensively. Therefore, one-dimensional optimization method of the combustion chamber flow field was formed.