P Khunthongjan, A Janyalertadun – Songklanakarin Journal of Science and Technology February 2012
The water current has used as the energy resource for long time however its velocity is very low therefore there are not found in wide range of uses. This study purposes accelerate water velocity by installing diffuser. The problems were analyzed by one dimension analysis and computational fluid dynamics (CFD); the domain covers the diffuser and turbine which substituted by porous jump condition is install inside. The flow was identified as axisymmetric steady flow, the inlet boundary is identified as uniform flow, all simulation use the same size of diffuser, only the diffuser angles are vary. The results show that velocities of water current in diffuser are increase when the diffuser angle are widen. The angle of diffuser is 20°, the velocity is increase to 1.96 times, compared to free stream velocity. If the angle was about 0-20° and 50-70° the force toward diffuser became high instantly; whereas the force toward the rotor will be still and the maximum rate of diffuser augmentation possibly was 3.62 and rotor power coefficient was 2.14.