Study On Heat Transfer And Phase Transition Process Of Water Vapor Transport In Air

As an important component of the modern aircraft carrier battle group,The ejection launch has become the first content of the research in many countries.At present,the mainstream ejection technology is steam ejection,and the foreign technology is more mature.Steam ejection device research start time is relatively backward in China,so there are still some problems to be solved at the steam ejection research trials.The high temperature,high pressure and high-speed water vapor escaping from the top of the cylinder gap,because the aircraft engine inlet pressure is very low,water vapor will be sucked into the engine.The vapor that has been sucked from engine entrance condensed into liquid water,which would have a very negative engine "turbulence" phenomenon,affecting the engine performance and life expectancy,even it will make the engine temporary parking.In this paper,the aircraft steam catapult is as research background;The space where from the engine cylinder slit to engine entrance is as research object;Flow and heat transfer of water vapor and phase transition process of water vapor is as research content;FLUENT numerical calculation And UDF self-defined programming is as research means;Mass flow rate of vapor and air and water condensation is as research goal;Through these methods for“Study on Heat Transfer and Phase Change Process of Diffused Water Vapor Flowing in Air"to deeper analysis and research.Make use of Eulerian-Eulerian model where mix in the mass transfer,energy transfer and momentum transfer equations to solve the problems of water vapor 's flow and heat transfers.The droplet nucleation and growth theory model was added to in the mass transfer models,to study the process of water vapor condensation.Water and water vapor by adding the thermodynamic properties of the parameters of the calculation model in the material properties,so as to make the calculation results more realistic and reliable.The conclusions are as follows:1)Through comparison and analysis,the density and viscosity showed a decreasing tendency with the increase of temperature,while the specific heat,thermal conductivity and sound velocity with increasing temperature first rise and then decline.2)The water vapor in the cylinder is mixed with the incoming air to be sucked into the engine,the others will continue to flow to the right side,becoming the vortex flow in the tail of the aircraft,the remaining gas outflow from the outlet.3)With the flow of air to the right,the water vapor temperature will drop,and the air temperature will rise,during this time there will be liquid water condensation.In the course of flow of air-vapor-liquid water three fluid mixing,the temperature tends to be consistent.Due to the movement of the air flowing in the tail area to form a vortex structure,the center of the vortex air temperature is only 308.7K,which is lower than the surrounding fluid temperature.4)As the engine inlet pressure decreases,the intake of water vapor by the engine gradually increases.When the pressure reaches-90000Pa,the water vapor has been completely sucked into the engine.5)With the increase of air velocity,the amount of water vapor will increase firstly and then decrease.When the velocity reaches 10m/s,the water vapor inhalation will reach 3.15kg/s.When the air velocity increased from 15m/s to 25m/s,the air mass flow rate at the inlet of the engine was greatly influenced.As the air mass flow rate continued to increase,the amount of water vapor sucked dropped sharply.When the aircraft reaches a certain speed,the water vapor has little effect in the engine.6)With the increase of vapor mass flow rate,the amount of air into the engine showed a decreasing tendency gradually,but the influence of vapor mass flow rate on the amount of air was not obvious.The vapor mass flow rate is increasing,with the vapor mass flow rate increases,but air is still dominant.7)With the decrease of engine inlet pressure,the amount of condensed water increases firstly and then decreases,and reaches the maximum at-50000Pa.The condensation amount of water vapor decreases with the increase of temperature.When the temperature reaches 140?150 ?,the condensation amount is approximately the same.With the increase of vapor mass flow velocity,the condensation amount of water vapor in the air will increase.When the water vapor flow rate reaches 30m/s,its condensing amount is stable at about 0.001kg/s.