Bulletin of the American Physical Society
68th Annual Meeting of the APS Division of Fluid Dynamics
Volume 60, Number 21
Sunday–Tuesday, November 22–24, 2015; Boston, Massachusetts
Session D14: Industrial Applications II |
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Chair: Kumaran Kannaiyan, Texas A&M University at Qatar Room: 202 |
Sunday, November 22, 2015 2:10PM - 2:23PM |
D14.00001: Effect of Fuel Additives on Spray Performance of Alternative Jet Fuels Kumaran Kannaiyan, Reza Sadr Role of alternative fuels on reducing the combustion pollutants is gaining momentum in both land and air transport. Recent studies have shown that addition of nanoscale metal particles as fuel additives to liquid fuels have a positive effect not only on their combustion performance but also in reducing the pollutant formation. However, most of those studies are still in the early stages of investigation with the addition of nanoparticles at low weight percentages. Such an addition can affect the hydrodynamic and thermo-physical properties of the fuel. In this study, the near nozzle spray performance of gas-to-liquid jet fuel with and without the addition of alumina nanoparticles are investigated at macro- and microscopic levels using optical diagnostic techniques. At macroscopic level, the addition of nanoparticles is seen to enhance the sheet breakup process when compared to that of the base fuel. Furthermore, the microscopic spray characteristics such as droplet size and velocity are also found to be affected. Although the addition of nanoscale metal particles at low weight percentages does not affect the bulk fluid properties, the atomization process is found to be affected in the near nozzle region. [Preview Abstract] |
Sunday, November 22, 2015 2:23PM - 2:36PM |
D14.00002: Design of a Laboratory-scale Marine Hydrokinetic device Uros Markovic, Maria Beninati, Michael Krane This study focused on the design of a small-scale marine hydrokinetic turbine, centered on a precision brake to facilitate rotational speed control, torque and power measurement. Generators of size and power capacity suitable for laboratory-scale experiments generally operate at vanishingly small efficiency, making accurate power measurements difficult. A small magnetic particle brake was attached to the shaft of a two-bladed model marine turbine (0.1 m rotor diameter). Preliminary testing of the device was performed to calibrate torque measurement by the magnetic brake. Further testing was conducted in the hydraulic flume facility (9.8 m long, 1.2 m wide and 0.4 m deep) at Bucknell University, to measure turbine torque and power to establish the range of rotational speed control. [Preview Abstract] |
Sunday, November 22, 2015 2:36PM - 2:49PM |
D14.00003: Resource Evaluation and Energy Production Estimate for a Tidal Energy Conversion Installation using Acoustic Flow Measurements Ian Gagnon, Ken Baldwin, Martin Wosnik The “Living Bridge” project plans to install a tidal turbine at Memorial Bridge in the Piscataqua River at Portsmouth, NH. A spatio-temporal tidal energy resource assessment was performed using long term bottom-deployed Acoustic Doppler Current Profilers ADCP. Two locations were evaluated: at the planned deployment location and mid-channel. The goal was to determine the amount of available kinetic energy that can be converted into usable electrical energy on the bridge. Changes in available kinetic energy with ebb/flood and spring/neap tidal cycles and electrical energy demand were analyzed. A system model is used to calculate the net energy savings using various tidal generator and battery bank configurations. Differences in the tidal characteristics between the two measurement locations are highlighted. Different resource evaluation methodologies were also analyzed, e.g., using a representative ADCP “bin” vs.\ a more refined, turbine-geometry-specific methodology, and using static bin height vs. bin height that move w.r.t.\ the free surface throughout a tidal cycle (representative of a bottom-fixed or floating turbine deployment, respectively). ADCP operating frequencies and bin sizes affect the standard deviation of measurements, and measurement uncertainties are evaluated. [Preview Abstract] |
Sunday, November 22, 2015 2:49PM - 3:02PM |
D14.00004: Numerical Simulation of Tethered Underwater Kites for Power Generation Amirmahdi Ghasemi, David Olinger, Gretar Tryggvason An emerging renewable energy technology, tethered undersea kites (TUSK), which is used to extract hydrokinetic energy from ocean and tidal currents, is studied. TUSK systems consist of a rigid-winged ``kite,'' or glider, moving in an ocean current which is connected by tethers to a floating buoy on the ocean surface. The TUSK kite is a current speed enhancement device since the kite can move in high-speed, cross-current motion at 4-6 times the current velocity, thus producing more power than conventional marine turbines. A computational simulation is developed to simulate the dynamic motion of an underwater kite and extendable tether. A two-step projection method within a finite volume formulation, along with an Open MP acceleration method, is employed to solve the Navier-Stokes equations. An immersed boundary method is incorporated to model the fluid-structure interaction of the rigid kite (with NACA 0012 airfoil shape in 2D and NACA 0021 airfoil shape in 3D simulations) and the fluid flow. PID control methods are used to adjust the kite angle of attack during power (tether reel-out) and retraction (reel-in) phases. Two baseline simulations (for kite motions in two and three dimensions) are studied, and system power output, flow field vorticity, tether tension, and hydrodynamic coefficients (lift and drag) for the kite are determined. The simulated power output shows good agreement with established theoretical results for a kite moving in two-dimensions. [Preview Abstract] |
Sunday, November 22, 2015 3:02PM - 3:15PM |
D14.00005: Why do Cross-Flow Turbines Stall? Robert Cavagnaro, Benjamin Strom, Brian Polagye Hydrokinetic turbines are prone to instability and stall near their peak operating points under torque control. Understanding the physics of turbine stall may help to mitigate this undesirable occurrence and improve the robustness of torque controllers. A laboratory-scale two-bladed cross-flow turbine operating at a chord-based Reynolds number $\approx 3 \times 10^4$ is shown to stall at a critical tip-speed ratio. Experiments are conducting bringing the turbine to this critical speed in a recirculating current flume by increasing resistive torque and allowing the rotor to rapidly decelerate while monitoring inflow velocity, torque, and drag. The turbine stalls probabilistically with a distribution generated from hundreds of such events. A machine learning algorithm identifies stall events and indicates the effectiveness of available measurements or combinations of measurements as predictors. Bubble flow visualization and PIV are utilized to observe fluid conditions during stall events including the formation, separation, and advection of leading-edge vortices involved in the stall process. [Preview Abstract] |
Sunday, November 22, 2015 3:15PM - 3:28PM |
D14.00006: Experimental Evaluation of a Method for Turbocharging Four-Stroke, Single Cylinder, Internal Combustion Engines Michael Buchman, Amos Winter V. Turbocharging an engine increases specific power, improves fuel economy, reduces emissions, and lowers cost compared to a naturally aspirated engine of the same power output. These advantages make turbocharging commonplace for multi-cylinder engines. Single cylinder engineers are not commonly turbocharged due to the phase lag between the exhaust stroke, which powers the turbocharger, and the intake stroke, when air is pumped into the engine. Our proposed method of turbocharging single cylinder engines is to add an ``air capacitor'' to the intake manifold, an additional volume that acts as a buffer to store compressed air between the exhaust and intake strokes, and smooth out the pressure pulses from the turbocharger. This talk presents experimental results from a single cylinder, turbocharged diesel engine fit with various sized air capacitors. Power output from the engine was measured using a dynamometer made from a generator, with the electrical power dissipated with resistive heating elements. We found that intake air density increases with capacitor size as theoretically predicted, ranging from 40 to 60 percent depending on heat transfer. Our experiment was able to produce 29 percent more power compared to using natural aspiration. These results validated that an air capacitor and turbocharger may be a simple, cost effective means of increasing the power density of single cylinder engines. [Preview Abstract] |
Sunday, November 22, 2015 3:28PM - 3:41PM |
D14.00007: Numerical study of crude oil fouling in a Taylor-Couette-type reactor Misha Crastes, Lydia Lagkaditi, Jonathan Ball, Junfeng Yang, Francesco Coletti, Sandro Macchietto, Omar Matar We consider the non-isothermal flow of crude-oil mixtures in a Taylor-Couette-type reactor; this flow is accompanied by the deposition of soft-solid wall-layers, commonly referred to as ``fouling”, driven by chemical reactions and phase separation. Three-dimensional CFD simulations are carried out to resolve the flow and temperature fields, as well as the volume fraction of the foulant phase. The simulations also account for the effect of evolving deposit rheology. The CFD predictions are validated against published results for isothermal flow, in the absence of fouling, in terms of the characteristics of the vortical structures that accompany the flow. In the presence of fouling, we examine the spatial distribution of the wall stresses as a function of the Reynolds and Taylor numbers, and demonstrate that wall regions exposed to higher (lower) shear stresses tend to form thinner (thicker) fouling layers. The simulation results capture the trends observed experimentally. [Preview Abstract] |
Sunday, November 22, 2015 3:41PM - 3:54PM |
D14.00008: A new framework to increase the efficiency of large-scale solar power plants. Shahrouz Alimohammadi, Jan P. Kleissl A new framework to estimate the spatio-temporal behavior of solar power is introduced, which predicts the statistical behavior of power output at utility scale Photo-Voltaic (PV) power plants. The framework is based on spatio-temporal Gaussian Processes Regression (Kriging) models, which incorporates satellite data with the UCSD version of the Weather and Research Forecasting model. This framework is designed to improve the efficiency of the large-scale solar power plants. The results are also validated from measurements of the local pyranometer sensors, and some improvements in different scenarios are observed. [Preview Abstract] |
Sunday, November 22, 2015 3:54PM - 4:07PM |
D14.00009: ABSTRACT WITHDRAWN |
Sunday, November 22, 2015 4:07PM - 4:20PM |
D14.00010: Numerical Investigation of the effect of adiabatic section location on thermal performance of a heat pipe network with the application in thermal energy storage systems Mahboobe Mahdavi, Saeed Tiari, Songgang Qiu Latent heat thermal energy storage systems benefits from high energy density and isothermal storing process. However, the low thermal conductivity of the phase change material leads to prolong the melting or solidification time. Using a passive device such as heat pipes is required to enhance the heat transfer and to improve the efficiency of the system. In the present work, the performance of a heat pipe network specifically designed for a thermal energy storage system is studied numerically. The network includes a primary heat pipe, which transfers heat received from solar receiver to the heat engine. The excess heat is simultaneously delivered to charge the phase change material via secondary heat pipes. The primary heat pipe composed of a disk shape evaporator, an adiabatic section and a disk shape condenser. The adiabatic section can be either located at the center or positioned outward to the surrounding of the container. Here, the effect of adiabatic section position on thermal performance of the system is investigated. It was concluded that displacing the adiabatic section outwards dramatically increases the average temperatures of the condensers and reduces the thermal resistance of heat pipes. [Preview Abstract] |
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