Calculation Research On Thermal Conductivity Of Aviation Kerosene At Sub/Supercritical Pressure

The thermal management system is very important to the cooling effect of the scramjet that works for a long time.The thermal conductivity is a very important heat transport parameter of aviation kerosene as a coolant.However,due to the extremely complex components of aviation kerosene,no researchers have used molecular dynamics to study the thermal conductivity properties of sub-/supercritical pressure aviation kerosene substitutes.Therefore,this article uses equilibrium molecular dynamics and non-equilibrium molecular dynamics simulation methods to study the thermal conductivity of the single component of aviation kerosene—n-decane.The main work of this paper is as follows:（1）The thermal conductivity of n-decane is simulated by EMD method by selecting4 all-atom force fields and 4 united atom force fields,and comparing the simulation results with NIST data,the study found that the joint atomic force field has a significant performance in predicting the thermal conductivity.Better than all-atom force field.（2）At supercritical pressure of 3MPa,the simulation methods of EMD and RNEMD were used to calculate the thermal conductivity of n-decane molecules under a combined force field,and the calculation results were compared with the NIST reference value of n-decane.The study found that the joint atomic force field SKS model performed best,and under the same force field,the overall average absolute deviation of the simulation results based on the EMD method was smaller than that of the RNEMD.（3）With the pressure of 0.1-5MPa,the thermal conductivity of n-decane is calculated based on the simulation of EMD and RNEMD respectively.Comparing the calculated results with the NIST reference value of n-decane,it is found that the overall average deviations of the simulation results of EMD and RNEMD are 3.32%and 6.75%,respectively.Comparing the simulation results with the experimental values of RP-3aviation kerosene,it is found that the overall average deviations of the simulation results of EMD and RNEMD are 2.05%and 6.34%.（4）The self-diffusion coefficient and radial distribution function of n-decane are further analyzed by molecular dynamics.When the temperature rises,the intramolecular energy increases and the slope of the mean square displacement increases,which accelerates the diffusion of n-decane molecules.Since the pseudoatoms CH₃ locate at the end of each n-decane molecules chain,the shift of the primary peaks ofg（r）_CH3-CH3indicates that the end to end distances of the n-decane molecules chains become larger with the increasing of the temperature,thus decreasing the thermal conductivity.