Francis turbines research and development (R&D) requires performance assessment through hydraulic laboratory model testing which can be assisted by auxiliary tools like computational fluid dynamics (CFD), widely used recently. CFD has a history of seeking and requiring ever higher computational performance (HPC) because of the parallelism where Graphics Processor Units (GPUs) have emerged as a major paradigm for solving complex computational problems. However, their implementation to CFD solvers is still a challenge and the tremendous computational power of the GPUs has been wasted. This work presents how the open source RapidCFD code, based on OpenFOAM and ported to Nvidia CUDA, enabled GPUs to be able of running almost entire simulations in thousands of parallel stream cores packed in small form factor hardware in order to solve the incompressible Reynolds-Average-Navier-Stokes (RANS) equations. The simulations were based on a full 3D Francis turbine case which consisted of a grid domain of 23 million cells, including spiral case with stay vanes, distributor, runner and draft tube. CFD results of shaft torque, static pressure and velocity components in steady state deploying a multiple reference frame (MRF) motion approach were compared with available experimental data for main operation conditions at different distributor opening angles: best efficiency operation point (BEP), part load operation point (PL) and full load operation point (HL). The obtained data showed that by transferring directly all the computations to the GPUs, it is possible to make CFD simulations faster compared with central processing units (CPUs). Thus, it is expected to obtain an affordable low computational cost in optimization processes or full range performance evaluations.
La problemática ambiental y la responsabilidad humana en el uso de recursos y sostenimiento ambiental se han vuelto cada vez más relevantes y apremiantes debido al acelerado ritmo de industrialización y urbanización, y al crecimiento de la población mundial. La falta de planeación adecuada amortigua el impacto en el entorno, lo que conlleva al agotamiento de los recursos naturales y la degradación del ambiente, generando desigualdades sociales y económicas. En este contexto, la comunidad mundial tiene que lidiar con sinnúmero de compromisos en su intento por garantizar una distribución justa de los recursos y las oportunidades. El pensamiento de Aquino en su doctrina y la lectura que de él han hechos pensadores contemporáneos, proponen principios éticos que se derivan del propio mundo natural y que guían el comportamiento humano hacia la realización del bien común, con implicaciones significativas para la ética medioambiental. La idea de que el mundo natural existe para beneficio de todos los seres humanos, y que es responsabilidad humana utilizarlo de forma que promueva el bien común, sigue siendo una perspectiva oportuna y valiosa en los actuales planteamientos sobre la responsabilidad ecológica.
This paper describes all the main features of the hydrokinetic devices developed during the HARVEST program. Such devices, which eliminate the well-known weaknesses of Darrieus turbines, are composed of two counter-rotating twin columns of cross flow water turbines (CFWT) built in a support structure with a twin towers shape. Among other advantages, it is shown that the twin towers geometry facilitates the optimal design of arrays of HARVEST Power Systems. In particular simple 2D models can be used in a first approach to predict power extraction of single-row arrays. Blade Element Momentum-Reynolds-Averaged Navier-Stokes Simulations (BEM-RANS) models are currently developed to yield a fast and accurate prediction of the power output produced by a row of many power systems. Relevant momentum source terms describing the rotor effects, which are required by this simplified modelling, are defined beforehand from a set of high-fidelity Unsteady Averaged Navier-Stokes Simulations (URANS) simulations for an isolated HARVEST Power System.
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