Numerical Study On The Deposition Process Of Aviation Kerosene RP-3 Under Supercritical Pressure

As coolant, when aviation kerosene RP-3 flows through the cooling ducts, the heat of engine heating fuels, and that will make aviation kerosene experience oxidative cleavage, pyrolysis, and carbon particles are formed. Carbon particles flow with kerosene, and affected by drag force, Saffman force, gravity, virtual mass force, et al. Under the effect of all these forces, carbon particles will deposit on the inside surface of pipe wall, clogge pipe and affect heat transfer between engine and kerosene, even burn engine when situation is serious. The physical model of this paper was a tube with 1.8 mm inner diameter and 2000 mm length. With Euler-Lagrange method, the deposition process of supercritical aviation kerosene (RP-3) in a cooling channel was numerically investigated, so it would be a reference to carbon deposition in aviation engine cooling ducts.Firstly, the particle deposition characteristics in vertical pipe were studied. It was found that particle diameter had an impact on the virtual mass force in vertical downward pipe. When kerosene had a low temperature (below the critical temperature), the effect of virtual mass force was strong and it shoule be considered. With the increase of kerosene temperature, the effect of virtual mass force began to decrease. It could be neglected when the temperature of kerosene was beyond 700K. Based on the effect of virtual mass force, the kerosene temperature was selected at 700K to discuss the particle deposition characterics. It was found that the particle deposition rate increased, and then decreased, and then continued to rise, and finally stabilized with the increase of particle diameter in vertical downward pipe, but the particle deposition rate increased and gradually stabilized with particle diameter in vertical upward pipe; the deposition rate rose with the kerosene temperature rising of 10μm carbon particle in vertical pipe; in the verticle downward pipe, the deposition rate of 10,50,70, 100μm carbon particle was lower on the condition of 5MPa outlet pressure than on 3MPa outlet pressure, and the rate was higher on the condition of 5MPa for 30μm carbon particle than 3MPa outlet pressure, and in the vertical upward pipe, 10μm carbon particle was lower on the condition of 5MPa outlet pressure than on 3MPa outlet pressure; the particle deposition rate decreased with the increase of kerosene inlet velocity.Secondly, the laws of deposition in horizontal pipe were studied, and the main particle diameter was 10μm. It was found that the particle deposition rate increased and gradually stabilized with particle diameter; the particle deposition rate rose with the rising of kerosene temperature; compared to the 3MPa outlet pressure, the particle was more difficult to deposite on the wall on the condition of 5MPa outlet pressure; the particle deposition rate decreased with the increase of kerosene inlet velocity.Thirdly, the particle deposition characteristics in inclined pipe were studied, and the main particle diameter was 10μm. It was found that the particle deposition rate increased and gradually stabilized with particle diameter; the particle deposition rate rose with the rising of kerosene temperature; compared to the 3MPa outlet pressure, the particle was more difficult to deposite on the wall on the condition of 5MPa outlet pressure; the particle deposition rate decreased and gradually stabilized with the increase of kerosene inlet velocity.Finally, the comparison was made about the deposition rate of particle at different flow directions, and it could be represented visual with "Heart-shaped map" about the rate of particle deposition in different directions. There was a lowest deposition rate in vertical upward flow direction and highest in horizontal flow direction.