Numerical Study On Cavitating Flow Of Cryogenic Fluids

With the manned space, deep space exploration and other large aerospaceactivities, increasingly demand for liquid rocket high-thrust, high-thrustrequirements would lead to a cryogenic fluid flowing through the liquid carrierrocket propulsion systems propellant cavitation phenomenon, which can seriouslyaffect the performance and reliability of the liquid carrier rocket. Therefore,accurate prediction of cryogenic cavitation is one of the key technologies forhigh-thrust liquid rocket. Characteristics and mechanis m of cryogenic cavitationhave important theory significance and engineering application value. Thecryogenic cavitation question is a temperature close to the saturation temperature ofthe fluid cavitation problems, with the type of room-temperature fluid cavitationmainly lies in the different degree of thermodyna mic effects. For cryogeniccavitation issues, to consider cryogenic fluid thermodynamic effect, by nu mericalsimulation carried out a study of cryogenic fluid steady and unsteady cavity flowcharacteristics, the main research work are as follows:Based on Rayleigh-Plesset bubble dynamics equation, consider the influenceof temperature, combined with the two phases of the thermal diffus ion equation andthe bubble thermal equilibrium equation, derived thermodynamic effect terms,phase correction and Zwart cavitation model mass transport source, establishconsidering the thermodynamic effect correction cavita tion model and numericalsimulation of the unsteady cavity flow of liquid nitrogen around the hydrofoil, thecalculated results agree well with the experimental data to verify the validity of themodel.Based on the theory of homogeneous equilibrium flow, with commercialsoftware FLUENT12as research platform, through user define function method areadded to the source in the energy equation, considering the effect of latent heat ofvaporization, while the introduction of cryogenic fluid physical parameters changewith the function of temperature. To simulate the flow around cylindrical hydrofoilcavitation of liquid nitrogen, comparison and analysis of the sensitivity of threekinds of cavitation cavitation model thermodynamic effect, think Zwart cavitatio nmodel suitable for the simulation of cryogenic fluid cavitation, and analyze theeffects of evaporation and condensation coefficient Zwart cavitation model oncavitation characteristics of cryogenic fluid, gives more suitable for the simulationof cryogenic fluid cavitation evaporation and condensation coefficient;Simulate the liquid nitrogen around different hydrofoil in steady and unsteady cavitating flow, analyzes the influence of three kinds of turbulence models andentrance turbulence viscosity ratio of cryogenic cavitation characteristics,Realizable k-turbulence model for steady and unsteady cavitating flow simulationin the cryogenic fluid, is not affected by the entrance turbulence viscosity ratio,application in the simulation of low temperature fluid cavitation characteristics.Select the appropriate numerical calculation method, and verified the validity of themathematical model and numerical calculation method using experimental data, hasformed a set of numerical simulation method for calc ulation of cavitationcharacteristics of cryogenic fluidBased on the numerical simulation method, liquid nitrogen and liquidhydrogen around2D cylindrical hydrofoil unsteady cavitating flow numericalsimulation, cryogenic cavitating flow of the two cryogenic fluid medium cavitationthermodynamic effect, comparative analysis of two the degree of influence of thethermodynamic effect of cryogenic fluid medium, and its impact mechanism foranalys is, liquid hydrogen cavitation thermodynamics effect is stronger than liquidnitrogen. To study the effects of flow velocity, flow temperature and the far fieldpressure on cavitation characteristics of cryogenic fluid, the pressure distribution,temperature distribution, liquid volume fraction distribution and cavity length varieswith the flow parameters are obtained, obtained in the same fluid medium, the flowparameters will also affect the thermodynamic effects.Numerical simulation of unsteady cavity flow around a2D NACA0015hydrofoil with liquid hydrogen, the study of various temperature, the evolution ofvacuolar and the law of vacuoles periodic shedding of temperature on vacuolarmorphology, bubble flow fieldstructure and dynamic properties of water, to revealthe mechanis m of the effect of temperature on unsteady cavity. Stream cavitationnumber and hydrofoil angle of attack on the the liquid hydrogen unsteady cavityflow. At the same time, research influence of flow cavitation number, attack angleand the combination of parameters on the cavity shape, tempera ture distribution andthe lift coefficient and drag coefficient.