Parallel CFD simulations of an original and redesigned hydraulic turbine draft tube

Hellström, J. Gunnar I.; Marjavaara, B. Daniel; Lundström, T. Staffan

doi:10.1016/j.advengsoft.2006.08.013

Cited by 42 publications

(19 citation statements)

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“…Traditionally, the draft tube design is based on simplified analytic methods, experimental prototypes, and recently due to the increase in computer parallel computing, by numerical methods such as computational fluid dynamics (CFD). 1 Due to their relevance on the turbine performance, there is a great interest in developing new methodologies to design and analyze the draft tube. 2,3 Similar studies were performed using geometric parameterization 1,4,5 based on one or more parameters that defined a single draft tube geometric feature (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube

Sosa

Urquiza

García

et al. 2015

Advances in Mechanical Engineering

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Any hydraulic reaction turbine is installed with a draft tube that impacts widely the entire turbine performance, on which its functions are as follows: drive the flux in appropriate manner after it releases its energy to the runner; recover the suction head by a suction effect; and improve the dynamic energy in the runner outlet. All these functions are strongly linked to the geometric definition of the draft tube. This article proposes a geometric parametrization and analysis of a Francis turbine draft tube. Based on the parametric definition, geometric changes in the draft tube are proposed and the turbine performance is modeled by computational fluid dynamics; the boundary conditions are set by measurements performed in a hydroelectric power plant. This modeling allows us to see the influence of the draft tube shape on the entire turbine performance. The numerical analysis is based on the steady-state solution of the turbine component flows for different guide vanes opening and multiple modified draft tubes. The computational fluid dynamics predictions are validated using hydroelectric plant measurements. The prediction of the turbine performance is successful and it is linked to the draft tube geometric features; therefore, it is possible to obtain a draft tube parameter value that results in a desired turbine performance.

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Section: Introductionmentioning

confidence: 99%

“…the cone angle or elbow radius). Hellstro¨m JGI et al 1 carry out CFD computations to evaluate an original and redesigned draft tube. With their CFD computations, they did not find any improvements in the pressure recovery of the two draft tube geometries.…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube

Sosa

Urquiza

García

et al. 2015

Advances in Mechanical Engineering

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“…The resulting computational times for the numerically rough simulations were in the range of 1-2 h, the coarsened surfaces needed 3-23 h and the unsteady simulation on the finest surface took 7 days. The simulations are computationally heavy and were performed on an in-house PC-cluster using 96-140 cores depending on available resources, for a description on the parallel performance of the cluster see Hellström et al (2007). …”

Section: Numerical Set Upmentioning

confidence: 99%

Effect of Spatial Resolution of Rough Surfaces on Numerically Computed Flow Fields with Application to Hydraulic Engineering

Andersson

Hellström

Andreasson

et al. 2014

Engineering Applications of Computational Fluid Mechanics

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ABSTRACT:In numerical simulations of flow over rough surfaces, the roughness is often not resolved but represented by a numerical model. The validity of such an assumption is investigated in this paper by ReynoldsAveraged Navier-Stokes simulations of flow over a surface with a large roughness. The surface was created from a high-resolution laser scanning of a real rock blasted tunnel. By reducing the geometrical resolution of the roughness in two steps, the importance of an appropriate surface description could be examined. The flow fields obtained were compared to a set-up with a geometrical flat surface where the roughness was represented by a modified form of the Launder and Spalding wall-function. The flow field over the surface with the lowest resolution was substantially different from those of the two finer resolutions and rather close to the results from the set-up with the wall-function. The results also yield that the finer the resolution is the more vorticity is formed close to the rough surface and more turbulence is generated.

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“…In recent years, numerical methods such as computational fluid dynamics (CFD) have been introduced in the design process, due to the rapid development in computer capacity and performance. New aspects of flow structures can thus be considered with parallel computer architectures (Hellstrom et al, 2007). Thus far, most three-dimensional (3D) studies on turbulent flows in turbo-machines for engineering purposes adopted Reynolds averaged Navier-Stokes (RANS) method with the k-ε family models (Lai, 2004;Xin et al, 2004;Gong, 2011;Galvan et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Assessment of Les Performance in Simulating Complex 3D Flows in Turbo-Machines

et al. 2012

Engineering Applications of Computational Fluid Mechanics

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This paper aims at making an assessment of the performance of the large eddy simulation (LES) method in simulating the complex vortical flow in a Francis hydraulic turbine. Firstly the principle of the LES method is presented. Then, three-dimensional turbulent flow of the Francis turbine under selected condition is simulated using the LES method with the Smagorinsky-Lilly model. In the hydraulic turbine, pressure distribution, vortex structures and other flow information are captured, from which the low pressure area beside the suction side of the blade and vortex structure in the draft tube can be seen clearly. Compared with the results from both experiments and simulations by the Reynolds average Navier-Stokes (RANS) method with the k-ε turbulent model, the LES results are proven to be more accurate in predicting the overall performance and interior flow characteristics of Francis hydraulic turbine. This work attempts to apply the LES method to simulate the flow field in the flow passages of the whole runner, cone, elbow and diffuser, thereby obtaining the instantaneous characteristics of hydroturbine, including the pressure distribution, vorticity field and streamlines.

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Parallel CFD simulations of an original and redesigned hydraulic turbine draft tube

Cited by 42 publications

References 1 publication

Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube

Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube

Effect of Spatial Resolution of Rough Surfaces on Numerically Computed Flow Fields with Application to Hydraulic Engineering

Assessment of Les Performance in Simulating Complex 3D Flows in Turbo-Machines

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