Computational Analysis of Flow Around a Scaled Axial-Flow Hydro Turbine

Water power energy harvesting has become an important and growing industry supported by research and significant interest and impetus from the government and commercial sector. Due to waters high power density, marine current energy is an attractive addition to other renewable energy technologies. That said, there is still much to be understood about the design, application, installation, operation, and maintenance of current-driven marine-hydrokinetic devices and with new designs coming out frequently it is imperative to understand the physics and dynamics involved. Recently, testing of the Sandia turbine, designed by University of California, Davis, Pennsylvania State and Sandia National Laboratories, took place at Pennsylvania State\u27s Applied Research Laboratory. The testing was performed with a 1:8.7 scale model of the Sandia turbine. The experiment successfully assessed the turbine\u27s power and cavitation performance, unsteady driveshaft loading, blade strain, unsteady tower pressure, flow field, and acoustics. Given the expense and time required for experimentation, commercial computational fluid dynamics codes, such as CD-Adapco\u27s Star-CCM+ can be used to simulate new designs both quickly and inexpensively. The goal of this research is to validate the results obtained using Star CCM+ to model the Sandia turbine as compared to the experimental results obtained by Pennsylvania State. To carry out the simulation, several unstructured grids were generated on which several unsteady simulations were run at the design point of a tip-speed ratio of 4. For this design point at 95% blade span, the chord Reynolds number is approximately 500,000 which equates to about 2,000,000 for the full scale turbine. In comparing model results to experimental data there was good agreement for power performance parameters, such as thrust and power coefficients, as well as downstream velocity profiles. With such good agreement it is optimistic that computational fluid dynamics models can be used to accurately predict the performance of future water turbine designs, thus reducing the high cost of research needed to develop novel current-driven marine-hydrokinetic devices.\u2

Five year prognosis in patients with angina identified in primary care : incident cohort study

Peer reviewedPublisher PD