Editor's Note: This is the sixth in a series of profiles provided by the Hydro Research Foundation that highlight potential future members of the hydroelectric power industry and their accomplishments.
The Hydro Research Foundation is actively supporting graduate students to conduct research related to conventional and pumped storage hydropower. These students are funded through the Department of Energy’s Water Power Program and industry partners through a five year $3.7 million dollar grant.
Daniel Leonard will graduate this coming semester with a Ph.D. in Engineering Science and Mechanics at Pennsylvania State University. After graduating with honors from Central High School, Daniel attended Penn State, where he developed an interest in fluid mechanics, obtained a B.S. in Aerospace Engineering in 2007, and a M.S. in Aerospace Engineering in 2010. Daniel chose to remain at Penn State in 2010 and pursue his doctorate in Engineering Science and Mechanics by studying computational fluid dynamics. Daniel hopes that his research can make significant contributions to hydropower.
Daniel’s research focused Computation of Cavitating Flow in Hyrdroturbines. Cavitation occurs in hydroturbines when the flow conditions are such that the pressure on some mass of fluid drops to vapor pressure for a sufficient duration. If this condition occurs, a vapor cavity will form in the liquid. In hydroturbines, as in pumps and marine propulsors, cavitation can cause a sharp decrease in efficiency, as well as erosion from collapsing vapor clouds, resulting in premature wear and large component repair costs. Furthermore, it is the present trend in the hydro industry to attempt to extract more power from current and future installations over a wider operating range. Consequently there is more current and expected operation at off-design conditions, where cavitation is likely to occur.
This research effort will result in computational solutions of cavitating flow in an actual hydroturbine geometry. Steady solutions of cavitating flow will be obtained through periodic simulations of a single turbine blade coupled with a single guide vane. Additionally, to capture the temporal dynamics and the full coupling between stationary and rotating components, unsteady cavitation simulations of the guide vanes, runner blades, and draft tube will be performed using Unsteady Reynolds Averaged Navier-Stokes (URANS) methods, as well as Detached Eddy Simulations (DES). The unsteady, averaged unsteady, and steady computations will be compared to experimental data. The computed results will provide insight into unsteady and average cavitating hydroturbine operation, and extend the state-of-the-art in cavitation modeling. Furthermore, a better understanding of the dynamics of cavitation in hydroturbines will allow the hydroelectric power industry to operate more efficiently, not just as an energy source, but as a business. After graduation, Daniel is actively seeking employment in the industry.