The Experts below are selected from a list of 11814 Experts worldwide ranked by ideXlab platform

Franz Nestmann - One of the best experts on this subject based on the ideXlab platform.

  • exit Blade Geometry and part load performance of small axial flow propeller turbines an experimental investigation
    Experimental Thermal and Fluid Science, 2010
    Co-Authors: Punit Singh, Franz Nestmann
    Abstract:

    Abstract A detailed experimental investigation of the effects of exit Blade Geometry on the part-load performance of low-head, axial flow propeller turbines is presented. Even as these turbines find important applications in small-scale energy generation using micro-hydro, the relationship between the layout of Blade profile, Geometry and turbine performance continues to be poorly characterized. The experimental results presented here help understand the relationship between exit tip angle, discharge through the turbine, shaft power, and efficiency. The modification was implemented on two different propeller runners and it was found that the power and efficiency gains from decreasing the exit tip angle could be explained by a theoretical model presented here based on classical theory of turbomachines. In particular, the focus is on the behaviour of internal parameters like the runner loss coefficient, relative flow angle at exit, mean axial flow velocity and net tangential flow velocity. The study concluded that the effects of exit tip modification were significant. The introspective discussion on the theoretical model’s limitation and test facility suggests wider and continued experimentation pertaining to the internal parameters like inlet vortex profile and exit swirl profile. It also recommends thorough validation of the model and its improvement so that it can be made capable for accurate characterization of Blade geometric effects.

Franz Nestma - One of the best experts on this subject based on the ideXlab platform.

  • exit Blade Geometry and part load performance of small axial flow propeller turbines an experimental investigation
    Experimental Thermal and Fluid Science, 2010
    Co-Authors: Puni Singh, Franz Nestma
    Abstract:

    A detailed experimental investigation of the effects of exit Blade Geometry on the part-load performance of low-head, axial flow propeller turbines is presented. Even as these turbines find important applications in small-scale energy generation using micro-hydro, the relationship between the layout of Blade profile, Geometry and turbine performance continues to be poorly characterized. The experimental results presented here help understand the relationship between exit tip angle, discharge through the turbine, shaft power, and efficiency. The modification was implemented on two different propeller runners and it was found that the power and efficiency gains from decreasing the exit tip angle could be explained by a theoretical model presented here based on classical theory of turbomachines. In particular, the focus is on the behaviour of internal parameters like the runner loss coefficient, relative flow angle at exit, mean axial flow velocity and net tangential flow velocity. The study concluded that the effects of exit tip modification were significant. The introspective discussion on the theoretical model's limitation and test facility suggests wider and continued experimentation pertaining to the internal parameters like inlet vortex profile and exit swirl profile. It also recommends thorough validation of the model and its improvement so that it canmore » be made capable for accurate characterization of Blade geometric effects. (author)« less

Anupam Sharma - One of the best experts on this subject based on the ideXlab platform.

  • Designing wind turbine rotor Blades to enhance energy capture in turbine arrays
    Renewable Energy, 2020
    Co-Authors: Behnam Moghadassian, Anupam Sharma
    Abstract:

    An inverse design approach is proposed to compute wind turbine Blade geometries which maximize the aggregate power output from a wind farm. An iterative inverse algorithm is used to solve the optimization problem. The algorithm seeks to minimize the target function, f=−CP,av, where CP,av is the average normalized mechanical power of all the turbines in the wind farm. An upper bound on the Blade planform area, representative of the Blade weight, is imposed to demonstrate how to incorporate constraints in the design process. The power coefficients (CP) of the turbines in the farm are computed by solving the Reynolds Averaged Navier Stokes equations with the turbine rotors modeled as momentum sources using the actuator disk model. The inverse design is carried out using the trust-region-reflective method, which is a nonlinear least squares regression solver. The computation cost is reduced by computing the Jacobian once every few iterations and approximating it using Broyden's method in between. The proposed design approach is first demonstrated to maximize the isolated performance of single- and dual-rotor wind turbines and subsequently used to design the Blades for a 3-turbine array and a ten-turbine array in which the downstream turbines operate directly in the wake of the upstream turbines. For a turbine-turbine spacing of four rotor diameters, the farm-optimized Blade designs increase the farm power output by over five percent and the optimized Blade geometries are found to be considerably different from the Blade Geometry optimized for isolated turbine operation. As the turbine-turbine spacing is increased to eight rotor diameters, the difference between the Blade Geometry optimized for farm operation versus that for isolated operation, is reduced.

  • inverse design of single and multi rotor horizontal axis wind turbine Blades using computational fluid dynamics
    arXiv: Fluid Dynamics, 2017
    Co-Authors: Behnam Moghadassian, Anupam Sharma
    Abstract:

    A method for inverse design of horizontal axis wind turbines (HAWTs) is presented in this paper. The direct solver for aerodynamic analysis solves the Reynolds Averaged Navier Stokes (RANS) equations, where the effect of the turbine rotor is modeled as momentum sources using the actuator disk model (ADM); this approach is referred to as RANS/ADM. The inverse problem is posed as follows: for a given selection of airfoils, the objective is to find the Blade Geometry (described as Blade twist and chord distributions) which realizes the desired turbine aerodynamic performance at the design point; the desired performance is prescribed as angle of attack ($\alpha$) and axial induction factor ($a$) distributions along the Blade. An iterative approach is used. An initial estimate of Blade Geometry is used with the direct solver (RANS/ADM) to obtain $\alpha$ and $a$. The differences between the calculated and desired values of $\alpha$ and $a$ are computed and a new estimate for the Blade Geometry (chord and twist) is obtained via nonlinear least squares regression using the Trust-Region-Reflective (TRF) method. This procedure is continued until the difference between the calculated and the desired values is within acceptable tolerance. The method is demonstrated for conventional, single-rotor HAWTs and then extended to multi-rotor, specifically dual-rotor wind turbines. The TRF method is also compared with the multi-dimensional Newton iteration method and found to provide better convergence when constraints are imposed in Blade design, although faster convergence is obtained with the Newton method for unconstrained optimization.

Punit Singh - One of the best experts on this subject based on the ideXlab platform.

  • exit Blade Geometry and part load performance of small axial flow propeller turbines an experimental investigation
    Experimental Thermal and Fluid Science, 2010
    Co-Authors: Punit Singh, Franz Nestmann
    Abstract:

    Abstract A detailed experimental investigation of the effects of exit Blade Geometry on the part-load performance of low-head, axial flow propeller turbines is presented. Even as these turbines find important applications in small-scale energy generation using micro-hydro, the relationship between the layout of Blade profile, Geometry and turbine performance continues to be poorly characterized. The experimental results presented here help understand the relationship between exit tip angle, discharge through the turbine, shaft power, and efficiency. The modification was implemented on two different propeller runners and it was found that the power and efficiency gains from decreasing the exit tip angle could be explained by a theoretical model presented here based on classical theory of turbomachines. In particular, the focus is on the behaviour of internal parameters like the runner loss coefficient, relative flow angle at exit, mean axial flow velocity and net tangential flow velocity. The study concluded that the effects of exit tip modification were significant. The introspective discussion on the theoretical model’s limitation and test facility suggests wider and continued experimentation pertaining to the internal parameters like inlet vortex profile and exit swirl profile. It also recommends thorough validation of the model and its improvement so that it can be made capable for accurate characterization of Blade geometric effects.

Puni Singh - One of the best experts on this subject based on the ideXlab platform.

  • exit Blade Geometry and part load performance of small axial flow propeller turbines an experimental investigation
    Experimental Thermal and Fluid Science, 2010
    Co-Authors: Puni Singh, Franz Nestma
    Abstract:

    A detailed experimental investigation of the effects of exit Blade Geometry on the part-load performance of low-head, axial flow propeller turbines is presented. Even as these turbines find important applications in small-scale energy generation using micro-hydro, the relationship between the layout of Blade profile, Geometry and turbine performance continues to be poorly characterized. The experimental results presented here help understand the relationship between exit tip angle, discharge through the turbine, shaft power, and efficiency. The modification was implemented on two different propeller runners and it was found that the power and efficiency gains from decreasing the exit tip angle could be explained by a theoretical model presented here based on classical theory of turbomachines. In particular, the focus is on the behaviour of internal parameters like the runner loss coefficient, relative flow angle at exit, mean axial flow velocity and net tangential flow velocity. The study concluded that the effects of exit tip modification were significant. The introspective discussion on the theoretical model's limitation and test facility suggests wider and continued experimentation pertaining to the internal parameters like inlet vortex profile and exit swirl profile. It also recommends thorough validation of the model and its improvement so that it canmore » be made capable for accurate characterization of Blade geometric effects. (author)« less