Investigation on heat transfer enhancement of supercritical hydrocarbon fuel in rotating channel interpolated with spiral wire

Abstract

Hypersonic vehicles carry their hydrocarbon fuels as the only regenerative fluid because the existing air-cooled turbine blades cannot meet the stringent heat transfer requirements, including aerodynamic heating in overload environments. In this study, supercritical-pressure n-decane was used as the working medium, and a spiral wire with a wire diameter and pitch of 0.1 and 10 mm was inserted into a smooth circular tube (inner diameter = 2 mm; length = 200 mm) for studying the convective heat transfer characteristics under different rotating speeds, mass flow rates, inlet temperatures, and heat fluxes and investigating the enhanced heat transfer effect of the spiral wire. Experimental results indicate that the overall heat transfer performance of the spiral-wire structure tube was improved by more than 1.3 times compared to that of the smooth tube. Further, at the trailing edge surface at 300 rpm, the Nusselt number increases by an average of two times; in the meanwhile, the PEC value for the reinforced tube is obtained as 1.25–1.68, indicating a better enhanced heat transfer capability in the rotating channel. The experimental results are compared and verified using a computational fluid dynamics method with SST k-ω turbulence model, revealing the maximum relative deviation to be within 13.56 %. The numerical simulation results explain the mechanism of the temperature differences between the leading- and trailing-edge surfaces within the centrifugal section and the reinforcing effect of the interpolated spiral wire. This study provides a novel orientation towards the application of aviation fuel for turbine blade cooling and the efficient heat transfer performance of cooling channels under accelerated conditions.