Numerical Simulation Of Combustion Process In Closed Cycle Of Underwater Thermal Power

The Li/SF6 heat source system is an advanced chemical energy propulsion system for storage.The advantage is that the reaction discharges high-energy heat without exhausting the waste gas outside.This forms a closed cycle and is not affected by the back pressure of the external environment,which is an ideal thermal power system for underwater use.The reaction of lithium and sulfur hexafluoride is very severe and difficult to control.In the submerged injection reaction,the entire combustion chamber is filled with molten lithium,and the reaction process is difficult to be observed in experiments.Therefore,numerical simulation methods play an important role in the research.The object of this study is the combustion reaction of sulfur hexafluoride gas with lithium liquid in a combustion chamber filled with molten lithium.First,the model is reasonably simplified.The Euler-Lagrangian method and the eddy dissipation model are used to simulate the immersion jet reaction flow field.The numerical simulation results are in good agreement with the literature data,verifying the feasibility of the mathematical physics model adopted.By analyzing the distribution of temperature,pressure,components,etc.and their formation causes in the combustion process,the structure and dimensions of the reaction zone were determined.Based on this,the effects of the initial temperature of lithium,the injection speed of sulfur hexafluoride,and the injection method on the combustion flow field were studied.As a result,it has been found that increasing the initial temperature of the lithium and increasing the sulfur hexafluoride injection velocity can shorten the time for the combustion chamber to reach a stable flow field,and can improve the system heat exchange capacity.For the stabilized combustion flow field,the sulfur hexafluoride injection velocity has a significant effect on the shape and distribution of the flow field,and the initial temperature of the lithium has little effect on the combustion flow field.Convection heat transfer can be significantly enhanced by the injection of two nozzles in opposite directions,and a better heat exchange capacity can be obtained by increasing the mass flow rate than a single nozzle.The structure and scale of the reaction zone in the Li/SF₆ heat source system were studied in this paper.The influences of initial conditions and injection methods on the combustion flow field were analyzed.The results provided a technical reference for the structural design and optimization of the closed cycle system combustion chamber of Li/SF₆heat source.