Abstract
The single and parallel twin vertical axis hydro turbines were numerical simulated by open code-OpenFOAM, emphatically studied on the interference effect such as torque and load of turbine as well as hydrodynamic performance influenced by the distance and rotation forms between twin turbines and analyzed the wake flow field to show the velocity profile distribution. Results show that average power of parallel twin turbines is always higher than the power of a single turbine, the closer the lateral distance between turbines, the higher the power. At the same time, opposite outward rotation is the best arrangement form for twin turbines to get more power and counteract the lateral force.