Computational and experimental study of effects of sediment shape on erosion of hydraulic turbines

Poudel, Laxman; Shrestha, B; Thapa, Bhola; Shrestha, Krishna Prasad; Shrestha, Nabin K.

doi:10.1088/1755-1315/15/3/032054

Cited by 8 publications

(11 citation statements)

References 4 publications

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“…However, the rivers are loaded with enormous sediment during May-October season, due to heavy rainfall and the weak and fragile geometry of the Himalayas. The incessant and stochastic nature of the monsoon rain in the mountainous catchment area of these rivers are also responsible for the generation of an enormous amount of sediment in these rivers (Pandit, 2005;Poudel et al, 2012). A specific case study (Chhetri et al, 2016) of sediment loading of the Langtang river, one of the rivers located in central Nepal, reveals the sediment loading data as follow:…”

Section: Introductionmentioning

confidence: 99%

“…The sediment loading is composed of minerals like quartz, feldspar, mica, granite, tourmaline, clay, organic matters etc. Detailed mineralogical analysis of the sediment content reveals the domination of hard minerals (hardness > 6 on Moh's scale) like quartz and feldspar (Bajracharya et al, 2008;Neopane & Sujakhu, 2013;Poudel et al, 2012). Generally, the hardness of turbine material is about 6 on Moh's scale.…”

Section: Introductionmentioning

confidence: 99%

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Numerical modelling of the sand particle flow in pelton turbine injector

Bajracharya

Shrestha

Timilsina

2021

J. Eng. Iss. Solut.

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Pelton turbine is commonly employed high head impulse type turbine. Pelton turbine injector is an integrated part of the Pelton turbine machine which serves the purpose of converting entire pressure energy of water to kinetic energy and also regulates the water flowrate, with partial opening hence governing the power production. Severe erosion in Pelton turbine injector is reported from field setting research studies. Since the jet is atmospheric pressure jet, there is few chances of occurrence of cavitation hence it can be understood that impact of sand particles is the major cause of erosion. Furthermore, with turbine operating in partial flow condition, more erosion is reported in the needle of injector. For a long spear type injector, this study explores the cause of erosion by modeling the motion of the sand particle flow in steady state jet. For numerical modeling of the flow, the realizable k-epsilon model is used and for modeling the particle flow, the Discrete Phase Model (DPM) is used. Three different operating condition of the injector is considered and 77000 particles were injected to the flow domain. It is observed from the numerical simulations that the more sand particle hits the nozzle-needle surface with partial opening of the injector.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical modelling of the sand particle flow in pelton turbine injector

Bajracharya

Shrestha

Timilsina

2021

J. Eng. Iss. Solut.

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“…It is well understood that mineral composition of sediment alters the erosion potential of the sediment [14]. Different minerals have different hardness [14][15][16] and different shape [2]. Minerals that are harder (measured on Moh's hardness scale) have higher potential to cause solid particle erosion.…”

Section: Mineral Compositionmentioning

confidence: 99%

“…Extensive discussion of the effect of these variables with erosion rate is discussed in [1] and more recently by [2].…”

Section: Impingement Conditionsmentioning

confidence: 99%

“…Higher sediment concentration with the domination of hard minerals such as quartz and feldspar are seen in Himalayan originating rivers [1,2]. Despite the incorporation of desilting/desanding arrangements, sand particles pass through the water conveying system thus have caused severe erosion damage to hydro-mechanical parts of hydroelectric power generating projects.…”

Section: Introductionmentioning

confidence: 99%

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Solid Particle Erosion Models and their Application to Predict Wear in Pelton Turbine Injector

Bajracharya

Shrestha

Timilsina

2020

J. Inst. Engineering

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Analysis of water quality of Himalayan originated rivers reveals the heavy sediment loading with a major portion of the sediment being hard mineral, quartz. Despite the incorporation of desanders to reduce the sediment content passing through hydro mechanical parts, significant wear is being reported in south-Asian hydroelectric projects. Repeated impact of such solid particles which are harder than the material of mechanical parts (mostly steel) is known to cause the erosion. Flow parameters, impact angle, mechanical properties of wall and particle, particle shape and size are commonly explored variables that affect the erosion of solid by the sediment-laden flow. In order to predict such erosion, starting with Finnie erosion model, several other erosion models considering aforementioned variables are proposed but are mostly case dependent. Application of numerical methods to understand flow problems constitutes the field of Computational Fluid Dynamics (CFD). Due to enclosed flow, reactions turbines took accelerated development in the investigations by CFD modeling. However, free surface jet and complex flow mechanism in buckets have been a major barrier to the application of CFD in case of Pelton turbines. Recent advancements in computational techniques, technological advancements have enabled to investigate flow in Pelton turbine by CFD. However, it is least understood which among the proposed erosion models will predict erosion occurring in Pelton turbine and assembly. This article explores about erosion in Pelton turbine, various erosion models and state of the art in modeling erosion of Pelton turbine injector. It is discussed which among the erosion models shall best predict the erosion occurring in the Pelton turbine injector. A short list of erosion models is then given which can be applied for the case of erosion in Pelton turbine injectors.

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