In this study, a computational analysis was performed for a vertical-axis turbine which was installed in a water pipe to collect unused energy from the flow inside the pipe. The optimized operating conditions of the turbine were identified by comparing the energy-collecting performance obtained at different tip-speed ratios (TSRs). The turbine achieved the maximum efficiency of 22% at a TSR of 2.4 and collected 33 kW. Additional analyses were conducted to verify the effects of tip clearance, which is the distance between the turbine blades and the pipe wall, which showed that a higher efficiency was obtained with a smaller tip clearance. We also verified the effects of the turbine’s operating conditions and tip clearance on the flow field around the blades and wake of the turbine.
