Preliminary design and performance analysis of a positive displacement hydraulic turbine

Positive displacement turbines (PDT) find their use in applications with low flowrate, high head and having lower specific speed requirement, which is below the operational range of the conventional turbines. In the present work, an initial PDT was designed using the governing equations of fluid flow to extract the unused energy from the hot water transportation pipelines. The turbine was of lobe type with two rotors each having four lobes. The tip clearance, side clearance and other leakage losses were considered while designing using fundamental principles coupled with the empirical co-relations from the literature. The initial design's performance analysis had been carried out numerically using commercial computational fluid dynamics (CFD) code ANSYS CFX. The objective of the present study was to reveal the performance of the preliminary design for the given conditions and examine the causes of pulsations in torque, pressure and flow rate from the fluid flow characteristics.