STEADY NATURAL CONVECTION IN A TILTED LONG CYLINDRICAL ENVELOPE WITH LATERAL ADIABATIC SURFACE, PART 2: HEAT TRANSFER RATE, FLOW PATTERNS AND TEMPERATURE DISTRIBUTIONS

Numerical results for the steady natural-convection heat transfer in a tilted cylindrical envelope with constant but different end temperatures (300 versus 80 K) and an adiabatic lateral wall are presented. This envelope is supposed to be a simplified model for the pulse tube in a pulse-tube cryocooler when the pulse tube is positioned at different orientations. Variation of the average heat transfer rate with the inclination angle, and details of velocity and temperature distributions, are provided for four typical inclination angles. The major numerical results are as follows. First, the flow pattern caused by the natural convection in the pulse tube is very complicated, characterized by the global circulation between the hot and cold end accompanied by several local recirculations, leading to a multicell structure of flow pattern. Second, from the temperature distribution, especially the section average temperature distribution, the heat transport mechanism of natural convection in the pulse tube may b...