Unidirectional Mass Force's Impact On The Spray Cooling Process Of Compressor

It is of great significance to improve the thermal cycling efficiency of aviation gas turbines.The Inter-turbine combustion technology has been fully applied and developed for the sake of increasing the amount of work done.However,the research on reducing compressor energy consumption is relatively rare.This paper attempts to explore and do the preliminary study on the influencing factors of the inter-stage cooling technique and to simplify it accordingly referenced by some design parameters of cascade size for an aero-engine compressor.The three-dimensional geometric model of the simple circular barrel runner and the single-blade cascade runner of the compressor were established.Based on the basic equations of thermodynamics,the analytic solution of droplet evaporation is derived by introducing the boundary conditions.And the Fluent software was used to simulate the evaporation of droplets in high temperature and high velocity air.The simulation parameters were optimized by means of comparing analytic solution to numerical simulation results,and the results were processed by software such as Fluent,Tecplot and Origin.The effects of unidirectional mass force spray parameters and airflow parameters on the droplet evaporation rate were analyzed;comparative analysis of cooling efficiency under different conditions has been done,expecting to make a small contribution to engineering applications.Through the analysis of the calculated results,we found that there was an equilibrium temperature in the droplet evaporation process.The droplet equilibrium temperature increases obviously with the increase of the air humidity,and increases little with the temperature change of the air stream.And the evaporation velocity of droplets decreases rapidly with humidity increase.The smaller the particle size of droplet unit volume is,the larger the evaporation surface area it corresponds to.The evaporation rate of the droplet in the gas flow increases squarely with the decrease of particle size.The smaller the initial particle size,the higher the droplet evaporation rate.As the initial particle size is 10?m,the gas flow rate is no more than 150m/s,it can maintain 60% or more of the evaporation rate.During the evaporation process,the evaporation of a single droplet is inhibited by the increase of the water vapor component in the surroundings.The space for the compressor blade-cascade flow path is small.When the airflow velocity is high,the droplets flow along with the air flow by the air drag force---aerodynamic forces.The impact on the evaporation rate from the spray cone angle and the initial droplet velocity can be ignored.Smaller air flow velocity indicates that droplets have longer time period of evaporation in the flow channel.At a flow velocity of 25m/s,the ultimate---extreme particle size of the droplets increased to 17?m when completely evaporated.Droplet evaporation rate strongly depend on droplet initial size and air velocity.When spraying water at the inlet of the stationary blade-cascade,the droplet will flow along with the gas flow and not hit the surface of the cascade.Thus,it won't cause any losses.Basically,the droplets in a low speed flow channel can be completely evaporated when they reach the outlet.Spraying water from back surface of the blade in the blade-cascade channel,the droplet trajectory was greatly influenced by the mass force.There is an optimum mass force with the different droplet initial sizes and the air velocities,which allows the droplets to evaporate for the longest time in the flow channel without hitting the blades.The mass force also promotes the mixing between the gas and liquid,and avoids the inhibitory effect on the droplet evaporate process by the air component.At the point,the droplet evaporation rate of the path under mass force is much higher than the stationary blade-cascade flow path.