Flow and Heat Transfer Mechanism of a Regenerative Cooling Channel Mounted with Pin-Fins Using Supercritical CO2 As Coolant

At extremely high Mach number (Ma >= 8), kerosene is faced with issues of cracking with a limited heat sink for regenerative cooling. Supercritical CO2 can be used as additional cooling method for regenerative cooling because of its excellent heat and mass transfer capability and it can easily convert heat into electricity for the engine electric system. In this study, pin-fins are applied to a regenerative cooling channel using sCO(2) to further enhance heat transfer at extremely high heat flux. Heat transfer and fluid flow are analyzed by the k-omega SST model considering effects of pitch ratio, solid materials and accelerations. From this study, compared with a smooth cooling channel, the pin-fin channel (Case 3) obtains a heat transfer enhancement of 3.08, a friction factor of 4.66, thermal performance enhancement of 1.84, and the maximum temperature of the heated surface is decreased by 36 % at Re = 45,000. The maximum velocity is found at the near-wall regions determined by the combined effects of temperature difference and accelerations. When the channel material is Cu with the high thermal conductivity, the maximum temperature is decreased by 37 % compared with a steel channel and the temperature distribution also becomes more uniform.