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

摘要

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% 13.5-trimethyl-benzene, were calculated and verified by contrast with RP-3 experimental data. The length and diameter of the stainless tube are 300 mm, 1.8 mm respectively. The inlet temperatures varied from 370 K to 770 K, and the operation pressure were 3 MPa, 4 MPa and 5 MPa. The mass flow were 2 g/s, 3 g/s and 4 g/s, with different heat flow density 300 kW/m~2, 400 kW/m~2, 500 kW/m~2 and 550 kW/m~2. The research results show that the calculated pressure drops agreed well with the experimental data when the temperature was lower than 720 K. The discrepancy of numerical and experimental data becomes gradually distinct after the temperature is higher than 720 K. 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.