Experimental Investigation On Heat Transfer Characteristics Of N-decane Under Supercritical Pressure

In order to meet the need of chemical regenerative cycle and to cool thecombustion wall in supersonic combustion ramjet engine, the fuel in the coolantchannel was in an extremely high temperature to make it crack and absorb moreenergy. And the fuel in the coolant channel was set to be under supercriticalpressure to avoid heat transfer deterioration and unstable oscillation the boilingprogress brought in. In this case, the fuel temperature had to be in pseudo criticalregion before reaching to the initial temperature of pyrolysis. As a result, it wasneeded to investigate the heat transfer characteristics in pseudo critical region andpyrolysis area to give technical support in scramjet coolant channel design.As the CFD technique in pyrolysis region was still needed to be improved, theexperimental investigation was taken in this paper. Firstly, the experimentalfacilities and data processing method were introduced. In order to make the dataaccurate, the systematic error in this experimental system was analyzed and fixedbased on the data processing algorithm, and the result turned to be a relatively highaccuracy. The random error of the direct measurements and total error of theindirect measurements were calculated, which make it more reasonable to evaluatesome data far away from the rest.After the error analysis, the repetitive tests were made to actually measure theaccuracy of this experimental system, and the ability of the system in differentregion were gained to give some support to future study.Under supercritical pressure, the data of n-decane convective heat transferwithout pyrolysis under different working condition was compared and analyzed.Based on the fix for supercritical fluid convective heat transfer coefficient in resentstudies, the effect heat flux put on the heat transfer coefficient was detailed studied.What’s more, the heat sink, heat transfer coefficient and temperature of the tube andfuel were compared under supercritical and subcritical pressure, which gave somesupport to the pressure selection in non-pyrolysis region in coolant channel.And under supercritical pressure, the data of n-decane convective heat transferwith pyrolysis under different working condition was compared and analyzed. Atlast, the convective heat transfer process with pyrolysis under supercritical andsubcritical pressure were compared, which gave some support to the pressureselection in pyrolysis region in coolant channel as well.