Heat transfer numerical calculation of ventilated brake disc with internal fusion heat pipe

In order to strengthen the heat dissipation of existing ventilated brake discs (VBDs), prevent thermal degradation, and improve the braking safety of vehicles, a new type of VBD incorporating an integral heat pipe in the body, i.e., heat pipe disc (HPD), was proposed. To examine the heat transfer performance of HPD and its improvement effect, detailed FLUENT-based numerical simulation calculations of heat transfer in both HPD and VBD were conducted under the same working conditions. The intrinsic relationships between the heat transfer performance of HPD and three influencing factors, namely liquid filling rate, heat flow density, and rotational speed, were investigated through numerical calculations, and the heat transfer performance of HPD was compared to that of VBD. Research results show that the optimal liquid filling rate of HPD is 35% at low heat flow densities (not exceeding 4 700 W·m^-2) and 40% at high heat flow densities (exceeding 4 700 W·m^-2). The thermal resistance of HPD decreases with increasing heat flow density and increases with increasing rotational speed. The heat transfer effect of HPD has been significantly improved compared to VBD. For example, at a liquid filling rate of 35%, rotational speed of 23.1 rad·s^-1, and heat flow density of 5 839 W·m^-2, the average and maximum temperatures of the surface of HPD reduce by 49 K and 53 K, respectively, compared to VBD. At the same time, the thermal resistance reduces by 28%. Although the deviation of the average temperature of the surface of HPD is slightly higher than that of VBD, the local over-temperature of HPD has been improved due to its superior heat dissipation ability. The pressurized blocks in the connecting space of HPD ensure its structural strength and pressure-bearing capacity. As a result, its predicted number of failure cycles is 269 times higher than that of VBD. So the proposed HPD can significantly reduce its operating temperatures by enhancing heat transfer, thus improving the lifespan and safety of VBD.