Investigations On Flow Instabilities And Heat Transfer Characteristics Of RP-3 Aviation Kerosene In A Vertical Tube Under Supercritical Pressures

In this paper,flow instabilities and heat transfer characteristics of RP-3 aviation kerosene in a vertical circular miniature tube under supercritical pressures are studied by experimental research and numerical simulation.An aviation kerosene surrogate model of 13 components is used to calculate the thermophysical properties of fluid.The inner diameter of the test section is 2 mm,and the fluid in the test section is in the laminar and transition regime.Two different type of flow instabilities are found in the experimental investigation.One type of flow instabilities is accompanied with heat transfer enhancement.At this time,the inner wall temperature was close to the pseudo-critical temperature.In this case,the flow instability was caused by the pseudo-boiling mechanism.The other type of flow instabilities occurs when the outlet temperature approaches the pseudo-critical temperature.Thermally-induced pressure oscillations due to drastic density variation is found to be the reason for this case.The effects of inlet pressure,wall heat flux and inlet Reynolds number on flow instabilities is also studied.Flow instabilities could be reduced with increasing inlet pressure or wall heat flux,but the effect of inlet Reynolds number on flow instabilities is complicated.The two types of flow instabilities above occur in the process of increasing the inlet Reynolds number.Stability boundaries and convective heat transfer correlation are obtained through the experimental data,which are used for the quantitative prediction of the occurrence of flow instabilities and the convective heat transfer if flow instabilities occur.The convective heat transfer characteristics of supercritical pressure aviation kerosene RP-3 in vertical circular tube are studied by numerical simulation.The effects of inlet pressure,mass flow,wall heat flux and inlet temperature on convective heat transfer are studied.It is found that higher pressure leads to reduced heat transfer coefficient.Increasing mass flow or inlet temperature contributes to convective heat transfer,while wall heat flux has a complicated effect on convective heat transfer: when wall heat flux is low,wall heat flux has no effect on heat transfer.When the heat flux density is high,the Nusselt number increases and the convective heat transfer is strengthened as the heat flux increases.