Investigation on the Flow Instability of Supercritical Hydrocarbon Fuels in Cooling Channels

Flow instability in regenerative cooling channels is an important issue for the thermal protection of hypersonic scramjet engines. Taking into account the dynamic process of the heat transfer and flow instability, a one dimensional transient model with several modules (including the cracking reaction, convective heat transfer, and rapid calculation of thermal properties) has been developed to investigate the flow instability characteristics of supercritical hydrocarbon fuels in cooling channels. The calculated results were compared and validated against the available experiments and numerical benchmarks, attaining good agreements. By virtue of the transient simulations, the dynamic flow patterns under different flow rates were studied in a single cooling channel with n decane being the working substance. Then, the influences of the operating pressure and heated length on the in tube flow were further investigated. In addition to the Ledinegg instability, several dynamic instability modes were detected under different external driving forces. It was also observed that under a specific range of pressure drop, the in tube flow could transition from the density wave oscillation to a new steady state. Moreover, this flow excursion was more likely to be triggered when decreasing the operating pressure or channel length