Numerical investigation on heat transfer characteristics of supercritical n-decane in a regenerative cooling channel with inverted pyramid trusses

Regenerative cooling is considered to be an efficient method for cooling aircraft engine combustion chambers. A regenerative cooling channel inserted with the inverted pyramid trusses is proposed. The impact of display mode on heat transfer performance is examined through a numerical investigation. The results show that the inverted and A-oriented structures have the best heat transfer and mechanical properties. The temperature of the bottom channel wall may be reduced by 76.3 K through the implementation of inverted pyramid trusses. The application of inverted pyramid trusses can effectively mitigate the deterioration of heat transfer commonly found in smooth channels. The notable enhancement in the heat transfer coefficient is primarily observed in the area encom-passing the truss and the downstream expanse of 12 mm trailing the truss. This phenomenon is attributed to flow acceleration and intricate vortices trailing the truss. For the inverted display mode, the influence of the truss pitch, the angle between the truss and the flow direction, and the truss rod diameter of the truss on the heat transfer were investigated. The difference in heat transfer performance when changing the pitch was reflected in the low heat transfer coefficient region downstream of the trusses. When the diameter and angle changed, the heat transfer performance was mainly dependent on the size of the horseshoe vortex and the arch vortex. Based on the simulated data, the fitted relations for both friction coefficient and Nusselt number were developed with fitting errors of less than 5 %.