Karthik R
Hello This is alright. Fluent meshing will recognize all volumes in your domain. This is the reason why you are seeing the 'Turbine' volume. If you don't need it in your analysis, you can simply mark it as 'Dead'.
Regarding the 3D streamline plot, is this a MRF simulation? Is this a steady run? When the streamline touches the solid walls of the turbine, the streamline should end. This is the behavior you should be seeing.
If this is a Fluent run, can you try plotting the pathlines in Fluent post-processing to understand the flow field? Can you also plot the velocity contour or vectors in Fluent to understand the flow?