Numerical Simulation Research On Low Temperature Ignition Of Can Annular Combustor

As a power device,gas turbines also have broad application prospects in polar environments.However,the climate conditions in the polar regions are extremely harsh,with an average temperature of-20℃ to-40℃ in the cold season in the Arctic Sea.Due to the poor atomization characteristics of fuel in low temperature environments,the working environment of the ignition nozzle deteriorates,posing a challenge to the reliability of gas turbine ignition.Therefore,it is necessary to conduct research on the impact of low-temperature environment on combustion chamber ignition characteristics,in order to improve the ignition performance of the combustion chamber.This thesis takes a can annular combustor as the research object,which adopts an indirect ignition method.At the beginning of ignition,the initial kernel generated by the ignition nozzle ignites the fuel inside the torch igniter,and the generated jet torch flows through the connecting pipe into the flame tube,thereby achieving ignition of the flame tube.This article uses numerical simulation methods to study the effects of low temperature conditions on the ignition performance of torch igniters and flame tubes.The flow field distribution,fuel distribution,and ignition process in low temperature environments were obtained,and the influence of intake temperature on the ignition process and ignition probability was explored.Based on this,a method to broaden the ignition boundary of the combustion chamber was proposed.This thesis mainly conducts the following research work.(1)Numerical simulation was conducted on a torch igniter,and the temperature range within which successful ignition can be achieved with constant fuel flow rate was obtained.The results showed that when the intake temperature is low,the flame core will be blown out by cold air during propagation,ultimately leading to ignition failure.The distribution of flow field and fuel distribution field in the igniter at different temperatures was obtained.The results showed that the fuel evaporation decreased with the decrease of inlet air temperature,resulting in poor low-temperature ignition performance;Numerical simulations were conducted on the ignition process at different intake temperatures,and the results showed that the decrease in intake temperature increased the time required for the igniter to achieve stable combustion.(2)Numerical simulation was conducted on a can annular combustor,and the results showed that as the inlet temperature decreased,the temperature and velocity of the igniter outlet jet decreased accordingly;There is a critical ignition temperature in the combustion chamber.When the inlet temperature is low,the jet torch at the outlet of the igniter cannot ignite the flame tube,resulting in ignition failure;By increasing the ignition oil gas ratio,the critical ignition temperature of the combustion chamber can be reduced to 253 K.Numerical simulations were conducted on the ignition process of the combustion chamber at different inlet temperatures.The results showed that when the inlet temperature was low,the rate of chemical reaction between the jet torch at the igniter outlet and the surrounding fuel vapor was slower,making it unable to propagate along the circumference,ultimately leading to the failure of the combustion chamber ignition.(3)Describing the different stages of the ignition process,a combustion chamber ignition probability prediction model was obtained and applied to a blunt body combustion chamber to verify the model.The results showed that the prediction model can predict the ignition probability of the can annular combustor;The ignition probability distribution of torch igniters and annular combustion chambers at different inlet temperatures was obtained,and the reasons for the difficulty in ignition under low temperature conditions were analyzed,including insufficient ignition energy,high flame stretching rate,and low fuel equivalent ratio;On this basis,by increasing ignition energy and changing ignition position,the ignition boundary has been widened,enabling the combustion chamber to successfully ignite at an inlet temperature of 234 K.