Numerical investigation of heat transfer characteristics and flow resistance of kerosene RP-3 under supercritical pressure

Abstract

An in-house three-dimensional Navier–Stokes code was used to investigate the heat transfer characteristics and flow resistance of kerosene RP-3 under supercritical pressure in a tube. For the numerical simulation, the thermophysical and transport properties of the surrogate fuel, which is consist of 53% (mole fraction) n-undecane, 18% 1-butylcyclohexane and 29% 1,3,5-trimethyl-benzene, were calculated and verified by contrast with RP-3 experimental data. The length and diameter of the stainless tube are 300mm, 1.8mm respectively. The inlet temperatures varied from 370K to 770K, and the operation pressure were 3MPa, 4MPa and 5MPa. The mass flow were 2g/s, 3g/s and 4g/s, with different heat flow density 300kW/m2, 400kW/m2, 500kW/m2 and 550kW/m2. The research results show that the calculated pressure drops agreed well with the experimental data when the temperature was lower than 720K. The discrepancy of numerical and experimental data becomes gradually distinct after the temperature is higher than 720K. When the bulk temperature is lower than the critical temperature, the pressure drops under different operating pressures are almost the same. While the bulk temperature is higher than the critical temperature, the diversity of pressure drop under different operating pressures becomes manifest gradually. The local Nusselt number firstly increased and then suddenly decreased at a certain position. The heat transfer deterioration was caused by the intensive variations of thermo-physical properties of the fuel under supercritical pressures. Furthermore, the larger the heat flux was, the earlier the turnover position appeared.