For sustainable growth, In-stream technology utilizing the flow energy available in the water with the help of a turbine gained the attention of researchers. The helical Savonius turbine, known for its superior starting characteristics and higher power coefficient than the conventional Savonius turbine has been selected in the present study. The numerical study analyzes the wake recovery distance, pressure, and velocity characteristics of the helical Savonius turbine for horizontal and vertical alignment, considering 0.9 m/s flow velocities and 0.9 optimal TSR. The numerically simulated results are validated against experimental data, showing good agreement. Velocity contours unveil higher velocity vortices at the tip of the advancing blade in case of vertical alignment and at the end plate and along the length of the rotor in case of horizontal alignment. Notably, the near, transition, far wake zone is found to be extended up to 2D, 2D to 4D, beyond 4D for vertically aligned turbine and 1.5D, 1.5D-3D, beyond 3D for horizontally aligned turbine. The wake recovery distance for vertically and horizontally aligned turbines are reported as 12D and 8D, respectively, enabling closer installation of horizontally aligned turbines compared to vertical ones. These findings are valuable for optimizing arrays of helical Savonius turbines to achieve maximal energy extraction. The study is of great importance to researchers and industrialists looking to improve power generation through in-stream technology.