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The effects of blockage ratio and boundary proximity on tidal turbine performance are quantified in this study using computational fluid dynamics (CFD). Reynold averaged Navier-Stokes (RANS) equations are solved using the commercial CFD code ANSYS CFX. Steady-state analyses are performed using a rotating frame of reference technique, and a shear stress transport turbulence model is used. Results from the numerical model are validated with experimental data. RANS CFD simulations are performed over tip speed ratios (TSRs) from 1 to 9. The simulation-based performance curve approximately match the experimental performance curve, with errors ranging from 4 to 9%. Blockage ratios from 0.02 to 0.19 are evaluated for a constant depth of two rotor diameters to study the effect of blockage on turbine performance. Results show that shaft power increased by 13 and 47% for TSRs of 5.11 and 9.05, respectively, when the blockage ratio increased from 0.02 to 0.19. Additionally, for these TSRs and blockage ratios the turbine thrust increased by 7 and 10%. The presence of a boundary layer resulted in a calculated thrust increases between 1.6 and 2.3% and power between 2.7 and 3.5% for the entire range of evaluated blockage ratios. Nomenclature A swept area of the rotor (m 2) C P turbine power coefficient C T turbine thrust coefficient P mechanical power generated by the turbine, W R turbine radius (m) V mean upstream flow velocity (m/s) Y + dimensionless wall distance ω blade tip angular velocity (rad/s) ρ density of water, (kg/m 3) programme developed a TCT design called RM1. This is a nonproprietary RM developed as a study object for open-source research [19]. Experiments using RM1 were conducted in the open channel of the University of Minnesota's St. Anthony Falls Laboratory (UMN-SAFL) [19]. These high-resolution laboratory

Tidal Current Turbine (TCT) blades are highly flexible and undergo considerable deflection due to fluid interactions. Unlike Computational Fluid Dynamic (CFD) models Fluid Structure Interaction (FSI) models are able to model this hydroelastic behavior. In this work a coupled modular FSI approach was adopted to develop an FSI model for the performance evaluation and structural load characterization of a TCT under uniform and profiled flow. Results indicate that for a uniform flow case the FSI model predicted the turbine power coefficient C P with an error of 4.8% when compared with experimental data. For the rigid blade Reynolds Averaged Navier Stokes (RANS) CFD model this error was 9.8%. The turbine blades were subjected to uniform stress and deformation during the rotation of the turbine in a uniform flow. However, for a profiled flow the stress and deformation at the turbine blades varied with the angular position of turbine blade, resulting in a 22.1% variation in stress during a rotation cycle. This variation in stress is quite significant and can have serious implications for the fatigue life of turbine blades.

Velocity profiles in tidal channels cause cyclic oscillations in hydrodynamic loads due to the dependence of relative velocity on angular position, which can lead to fatigue damage. Therefore, the effect of velocity profile on the load variation and fatigue life of large-scale tidal turbines is quantified here. This is accomplished using Fluid Structure Interaction (FSI) simulations created using the ANSYS Workbench software, which couples the fluid solver ANSYS CFX to the structural solver ANSYS transient structural. While these load oscillations only minimally impact power and thrust fluctuation for rotors, they can significantly impact the load variations on individual rotor blades. To evaluate these loadings, a tidal turbine within a channel with a representative flow that follows a 1/7th power velocity profile and an onset turbulence intensity of 5% is simulated. This velocity profile increases the thrust coefficient variation from mean cycle value of an individual blade from 2.8% to 9% and the variation in flap wise bending moment coefficient is increased from 4.9% to 19%. Similarly, the variation from the mean cycle value for blade deformation and stress of 2.5% and 2.8% increased to 9.8% and 10.3%, respectively. Due to the effect of velocity profile, the mean stress is decreased, whereas, the range and variation of stress are considerably increased.

The current paper describes the effect of insulation thickness in a vacuum resistance furnace. An existing furnace was optimized for insulation thickness using analytical and numerical studies. Furnace heating efficiency was improved up to 64% by controlling the heat flow at the insulation face. The numerical results were validated experimentally and vice versa. The numerical results predicted a decrease in heat flow of 70%, while the experimentally achieved value was 64%. The percentage difference in numerical and experimental results was calculated to be 1.5–5% maximum in temperature value. The effect of mesh finesse was evaluated for thermal analysis and it was concluded that a very little difference of 5 °C occurs when element size is reduced 5 times. The study using numerical methods will help in designing better and upgraded furnaces with greater energy savings. Also, the application of numerical methods is proposed as an effective design and performance prediction tool during manufacturing and operational activities of vacuum furnaces, respectively.