Rotating Rayleigh-Benard convection in a cylindrical cell with aspect ratio two

Turbulent thermal convection occurs for example in the Earth's atmosphere and in the Earth's liquid outer core, which can be represented by the rotating Rayleigh-B{\'{e}}nard problem. We investigate the effect of rotation on heat transport and the presence of the large-scale circulation (LSC) in a cylindrical cell with aspect ratio $\Gamma=2$. The Rayleigh number $Ra$ in these experiments is varied between $2\times 10^8$ and $1.5 \times 10^9$, with Prandtl number $Pr\approx 4.4$. Non-rotating measurements of heat transport agree with literature data (both for cells with $\Gamma=1$ and $2$). Heat transport in rotating Rayleigh-B{\'{e}}nard convection (rotation vector parallel with the cylinder axis) is increased by up to 20\% ($Ra=3\times 10^8 $), which is larger than reported heat transfer enhancements for $\Gamma=1$ cells (and similar $Ra$). The onset of this enhancement by rotation is located at a higher Rossby value than for the cell with $\Gamma=1$. This is likely caused by the weaker, elliptical LSC, allowing Ekman pumping to take over heat transport more easily. The disappearance of the LSC around $Ro=7$ is also indirectly confirmed by temperature measurements along the sidewall of the convection cell.