The transonic turbulent flows around the NASA Common Research Model is simulated to investigate the capability of the Cartesian-grid-based flow solver UTCart in 3D high Reynolds number flow simulations. Firstly, the framework of UTCart is explained. UTCart consists of an automatic Cartesian grid generator and a compressible flow solver. The immersed boundary method with a turbulent wall function is used in the flow solver to reproduce the turbulent boundary layer. The updates for UTCart related to the boundary heat flux and the calculation method for the cutoff distance are also described. Using UTCart, the medium grid (approx. 50 million cells) around the NASA-CRM is generated in 43 minutes. Compared with the grid converged value, the drag coefficient at the cruise condition has 24 drag count (8%) and 16 drag count (5%) differences in the medium and fine grid (approx. 97 million cells) results, respectively. Although the drag coefficient is slightly overestimated, all the component-wise aerodynamic coefficient shows a consistent trend of grid convergence. Furthermore, the qualitative flow features including flow separation at high angles of attack show a fair agreement with the experimental data and the computational results on the conventional body-fitted grids.