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A User’s Guide

Experimental and numerical studies on melting phase change heat transfer in open-cell metallic foams filled with paraffin

Theory Of Wing Sections Including A Summary Of Airfoil Data

Wind turbine wakes are one of the most important aspects in wind power meteorology because they decrease the power production and increase the loading of downstream wind turbines. Therefore, there is a continuous need to find a ‘good’ wake model to properly plan wind power plant-level control strategies, predict the performance and understand the fatigue loads of turbines. In this paper, six widely used approaches of wake modelling (Jensen, Larsen, Dynamic Wake Meandering, Fuga and, Ellipsys3D LES and RANS together with their interpretations) that were developed at Technical University of Denmark, are described and the model subcomponents are analysed. The models are evaluated using data from the Sexbierum (onshore) and the Lillgrund (offshore) wind farms to understand how to best utilize them. The paper provides a comprehensive conceptual background to wake modelling combined with the overview of the state-of-the-art models including their implementations on operating wind farms.

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Wind turbine wake models developed at the technical university of Denmark: A review

We show the capability of a numerical simulation in capturing the dynamic and unsteady flow effects inside a centrifugal pump due to the impeller-volute interaction. The object of the study is a commercial centrifugal water pump with backward curved blades, which is built within a vaneless single tongue volute. For the numerical simulation, the viscous Navier-Stokes equations are handled with an unsteady calculation and the sliding mesh technique is applied to take into account the impeller-volute interaction. In keeping the unsteady terms of the equations active it is possible to correctly simulate the effects of the blade passage in front of the tongue and both the flow and pressure fluctuations induced. Time averaged numerical results are compared with the experimental performance curve. The numerical flow analysis allows the study of different variables which are always difficult to measure experimentally. The dynamic variables obtained with the proposed numerical model are compared with the experimental data

Numerical Simulation of the Dynamic Effects Due to Impeller-Volute Interaction in a Centrifugal Pump

This paper presents the functional characterization of a centrifugal pump used as a turbine. It shows the characteristics of the machine involved at several rotational speeds, comparing the respective flows and heads. In this way, it is possible to observe the influence of the rotational speed on efficiency, as well as obtaining the characteristics at constant head and runaway speed. Also, the forces actuating on the impeller were studied. An uncertainty analysis was made to assess the accuracy of the results. The research results indicate that the turbine characteristics can be predicted to some extent from the pump characteristics, that water flows out of the runner free of swirl flow at the best efficiency point, and that radial stresses are lower than in pump mode.

/pdf/performance-of-a-centrifugal-pump-running-in-inverse-mode-34cakxny5a.pdf

Performance of a centrifugal pump running in inverse mode

In the North Sea, an array of wind profiling wind lidars were deployed mainly on offshore platforms. The purpose was to observe free stream winds at hub height. Eight lidars were validated prior to offshore deployment with observations from cup anemometers at 60, 80, 100 and 116 m on an onshore met mast situated in flat terrain. The so-called “NORSEWInD standard” for comparing lidar and mast wind data includes the criteria that the slope of the linear regression should lie within 0.98 and 1.01 and the linear correlation coefficient higher than 0.98 for the wind speed range 4–16 m∙s−1. Five lidars performed excellently, two slightly failed the first criterion and one failed both. The lidars were operated offshore from six months to more than two years and observed in total 107 months of 10-min mean wind profile observations. Four lidars were re-evaluated post deployment with excellent results. The flow distortion around platforms was examined using wind tunnel experiments and computational fluid dynamics and it was found that at 100 m height wind observations by the lidars were not significantly influenced by flow distortion. Observations of the vertical wind profile shear exponent at hub height are presented.

/pdf/hub-height-ocean-winds-over-the-north-sea-observed-by-the-3edmvlklnm.pdf

Matthew Stickland

Papers

Performance of a centrifugal pump running in inverse mode

Hub Height Ocean Winds over the North Sea Observed by the NORSEWInD Lidar Array: Measuring Techniques, Quality Control and Data Management

CFD study of Jet Impingement Test erosion using Ansys Fluent® and OpenFOAM®

Identification of phenomena preceding blower surge by means of pressure spectral maps

A numerical analysis of buoyancy-driven melting and freezing