Investigation Of Atomization,Mixing And Evaporation On Two-phase Detonation In Pulse Detonation Engine

Pulse detonation engine(PDE)is an innovative propulsion system that utilizes repetitive detentions to produce thrust and power.It has a broad application prospect in future aerospace and weapon fields with the advantages of high thermal cycle efficiency,hardware simplicity,light weight and wide working scope.Based on the characteristics of fuel atomization,evaporation and gas/liquid mixing and detonation process in pulse detonation engine,one-dimensional and two-dimensional Euler-Lagrange model of two phase detonation in pulse detonation engine is established in this paper.According to the space-time conservation element and solution element theory,calculation format of gas phase one and two dimensional conservation element and solution element(CE/SE)method is derived,while the gas and liquid equations are respectively calculated by CE/SE method and fourth-order Runge-Kutta method.Based on the simulation of atomization,evaporation and gas-liquid mixing and deflagration detonation transition(DDT),the PDE's cold and hot experiments are carried out.The main contents are as following.(1)The one-dimensional or two-dimensional Euler-Lagrange model of two phase detonation are established,while the gas and liquid equations are respectively calculated by CE/SE method and fourth-order Runge-Kutta method.The effects of droplets number,droplets diameter,Rosin-Rammler distribution model,fill speed and fill style on DDT are analysed.Numerical results show that the one-dimensional or two-dimensional Euler-Lagrange model is suitable for simulation.The modified FIPA model is suitable for atomization of PDE.Increasing the fill speed,the axial inlets can all accelerate the liquid atomization,improve the gasoline-air distribution performance and shorten the DDT distance and time.(2)To investigate inlet temperature,equivalence ratio,multi-cycle working process on the working process of PDE,the two-dimensional Euler-Lagrange model considering chemical reaction mechanism for two phase detonation is built.Numerical results show that increasing the inlet temperature can accelerate the liquid atomization and evaporation,shorten the DDT distance and time and reduce the peak pressure of detonation wave;when equivalence ratio is less than 1.1,increasing the equivalence ratio can shorten the DDT distance and time and increase the peak pressure and speed of detonation wave;when equivalence ratio is greater than or equal to 1.1,increasing the equivalence ratio,can slightly shorten the DDT distance and time and increase the speed of detonation wave,but has a very small influence on the peak pressure of detonation wave.The multi-cycle working process in PDE is more complicated;with the increasing of cycle times,propagation velocity of detonation wave was increased,the DDT distance and time was decreased,until PDE was stable;Due to lack of gasoline caused by the evaporation of gasoline,PDE performance is better when the reactant equivalent is greater than 1.(3)To investigate the effects of atomization and mixing of gasoline and air on pulse detonation engine installed by the mixing chamber,the Euler-Lagrange model for two phase detonation with coordinate transformation is built.According to numerical results,the gasoline/air pulse detonation engine's cold test platform is build,the venturi tube,baffle,blender and the other mixed chamber structure are designed.This experimental study of the effect of mixing chamber structure on fuel atomization,evaporation and two-phase mixing process is carried out.Based on the effects of pulse detonation fuel atomization,evaporation and gasoline/air mixture,the gasoline/air pulse detonation engine's hot test platform is built.This experimental study of DDT time and distance,working frequency of PDE is carried out.Numerical and experimental results show that the venturi can accelerate the liquid atomization,improve the gasoline-air distribution performance and shorten the distance and time of DDT.When the injector is installed at the throat of venturi,PDE has the shortest DDT distance and time;if the detonation tube can be completely filled by air,smaller venturi is selected in order to improve the effect of atomization and mixing,increase working frequency and peak pressure of detonation wave.PDE has the shortest DDT time and distance,highest working frequency when nozzle is installed in venturi throat.When the operating frequency is low,the peak pressure of PDE by installing venturi and baffle combination structure is the highest.When the PDE needs higher operating frequency,the operating frequency of PDE by installing venturi and baffle combination structure is the highest.In the experimental range the effect of atomization and mixing can be improved by installing better structures of the mixing chamber in order to increase the operating frequency of PDE.In this paper,numerical and experimental studies of atomization,mixing and evaporation on two-phase detonation in pulse detonation engine are carried out.The results show that one-dimensional and two-dimensional Euler-Lagrange model of two phase detonation in pulse detonation engine can effectively simulate the process of atomization,mixing,evaporation and detonation,modified FIPA model is suitable for atomization in PDE,the mixing chamber can reduce the size of fuel droplets,improve the particle size distribution,shorten the DDT time and distance,has important theoretical significance and practical engineering value.