Numerical Simulation On The Flow And Heat Treansfer Of N-Decane In Supercritical Condition

Achieving higher-speed flight is the goal pursued by scientists in the aerospace field of various nations entire world.The development of hypersonic vehicles(Mach number greater than 5)has become a symbol of national defense technology and military capabilities.The research and development of scramjet plays a crucial character in the realization of hypersonic flight,which is a strategic commanding point for the development of all countries since the 21 st century.The active regenerative cooling method uses the fuel used inside the scramjet to cool the surface of the engine.It among the technical methods to realize the resultful thermal protection of scramjet at present.Due to the special working environment of the regenerative cooling system,the hydrocarbon fuel is usually in a supercritical state,and the flow of the hydrocarbon fuel in this state is very complicated.Especially when the physical properties of the hydrocarbon fuel change drastically near the critical temperature,which is difficult to conduct experimental research on it.We simulate the interchange of heat course of hydrocarbon fuel flow in the pipe by numerical calculation approach,which can obtain the detailed flow distribution arguments and complete the operation status difficult to complete in the experiment.Firstly,based on this research background,this paper uses hydrocarbon fuel n-decane as the working fluid.We have access to the commercial software Fluent to reappear the flow and interchange of heat course of n-decane in a supercritical pipeline based on the SST k-?turbulence model.The characteristic physical parameters of the working medium were imported into the Fluent having access to the piecewise-linear method.A geometric model of the rectangular cooling channel with the n-decane heating wall on one side under supercritical condition was established,and the interchange of heat course of n-decane flow was reproduced.The grid irrelevance and numerical calculation accuracy of the established model were verified.Secondly,the flow heat transfer of n-decane in the cooling channel with fixed initial parameters was simulated,and the temperature pattern,density pattern,velocity pattern and turbulent kinetic energy were discussed at diverse times.The research consequences indicate that in the radial section of the channel,the velocity of the n-decane is inverted "U" shaped.The allocation of temperature and density of n-decane is not uniform,and thermal stratification occurs.With the enhancement of retention time,the thermal stratification becomes more prominent.At the axial section of the channel,turbulent kinetic energy accelerates with the addition of retention time.Finally,three different rectangular pipe models with single-side wall heating are established,bottom heating,side heating,and top heating.On the foundation of previously mentioned,the physical field parameters of n-decane,the impression of thermal flux density,pressure,entry mass flow and entry temperature on the convective thermal transmission process is discussed,and the affection of three diverse heating faces on the flow thermal transmission characteristics is analyzed.The research consequences indicate that compared with other parameters,the pressure has no prominent impact on the variation of physical parameters within the range of numerical calculation,and the appropriate enhance of thermal flux,mass flow rate or decrease of entry temperature is beneficial to accelerate the convective thermal transmission capability in the cooling access.When the mass flux at the entry is below 4g/s,gravity has an obvious impression on the convective thermal transmission of n-decane flow.When the direction of heat transfer along the radial direction is the same as the direction of gravity,gravity promotes heat exchange.Gravity inhibits heat exchange when heat diffuses in a radial direction opposite to gravity.