Research On Lquid Fuel Flash Atomization Experiment And Numerical Simulation

With the increasingly serious energy crisis and environmental pollution problems,pollutant emission standards have been becoming increasingly stringent,and reducing pollutant emissions has become a necessary requirement for high-performance gas turbines.As one of the most important performance indexes of gas turbine combustor,the fuel atomization quality is of great significance to research.According to whether the liquid is overheated,the fuel atomization can be divided into liquid jet breakup atomization and flash evaporation atomization.The flash atomization process involves gasification of low-volatile fuel and bubbles generation in the droplet,which increases the gas-liquid two-phase interactions,strengthens the droplet breakage and effectively improves the combustion characteristics of the engine.At present,due to lack of systematic research on the mechanisms and control factors of flash atomization,the flash atomization characteristics of two liquid fuels were studied in this paper.Firstly,the macroscopic morphology and particle size of water/ethanol solution flash atomization were studied experimentally.Because there is little influence of the fuel type on the rule of flash atomization,according to the experimental results,the influence of diesel flash atomization and combustion characteristics were studied by numerical simulation.The main work contents are as follows:(1)Design and establishment of the experimental rig of flash atomization;through coMParable analysis of the spray forms of flash atomization and ordinary atomization,the results show that the flash atomization acts mainly within a certain range,and the distribution of spray droplets has a clear boundary between high and low concentration,furthermore,the distribution of spray droplets in the near field is relatively sparse,the farther away from the nozzle,the more droplets number,and the shape of spray beam changes from hollow cone to solid cone.(2)Measurement of the spray particle size using laser particle size analyzer when water/ethanol solution begins to the flash.By analysis of the effects of parameters such as injection temperature,injection pressure and mixing ratio on the flash atomization,it is found that increasing the injection pressure,improve fuel temperature,increase the mixing ratio can all improve the flash atomization effect,as a result,obtaining more uniform finer fog field.(3)Investigation of diesel flash atomization rules and combustion characteristics by numerical simulation.The results show that low concentration fuel is distributed in the front and the edge of diesel flash atomization spray beam,and high concentration fuel area is formed in the tail.The fuel evaporation is increased and the maximum temperature in the main combustion area is reduced through applying the flash atomization to the combustion chamber.However,due to tincrease of the atmospheric liquid disturbance induced by "micro-explosion effect" of flash atomization,the temperature distribution of the high temperature area is asymmetric.