Investigation of flow resistance characteristics of endothermic hydrocarbon fuel under supercritical pressures

The characteristics of flow resistance of a typical hydrocarbon fuel (RP-3) flow through adiabatic horizontal miniature tubes at supercritical pressures are experimentally investigated for both laminar and turbulent flow. The experiments are conducted by using a long tube measuring section and a short tube measuring section simultaneously in order to eliminate the effect of local pressure drop. In these experiments, the temperature of RP-3 changes from (295 to 789) K and the reduced pressure (P/Pc, Pc=2.33 MPa) ranges from 1 to 2.58, the mass flux is up to 1572.7 kg/(m2·s). Test results indicate that frictional pressure drops for various supercritical pressures at the same mass flux can be considered as equal with each other when the reduced temperature Tb/Tpc<0.95. When Tb/Tpc>0.95, difference appears and increases with the increase of Tb/Tpc. Additionally, the friction factor (f) of the supercritical fluid for turbulent flow has a critical value at Tb/Tpc=1, the values of f at this point for all pressures and mass fluxes are equal with each other. Moreover, at the same mass flux, there are two corresponding friction factors for the same Re, one is in the region of Tb/Tpc<1, the other is in the region of Tb/Tpc>1. Finally, classical correlations of friction factor is inapplicable when Tb/Tpc>0.95 at supercritical pressure and a new correlation has been obtained based on the experimental data.