Numerical investigation of the effect of leakage flow through erosion-induced clearance gaps of guide vanes on the performance of Francis turbines

Chitrakar, Sailesh; Dahlhaug, Ole Gunnar; Neopane, Hari Prasad

doi:10.1080/19942060.2018.1509806

Cited by 26 publications

(15 citation statements)

References 27 publications

(32 reference statements)

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“…In any cases, the change in peak pressure pulsation with reference to NACA 0012 hydrofoil was negative, lowest value for NACA 4412 hydrofoil. This agrees with the past study that asymmetric GV profile has the least effect on pressure pulsation (Chitrakar, Thapa, Dahlhaug, and Neopane, 2017;Koirala, Neopane, Shrestha, Zhu, and Thapa, 2017;Chitrakar, Dahlhaug, and Neopane, 2018). Since all these studies were conducted with the clearance gap in all GVs, the distinguished effects of only leakage flow were not studied.…”

Section: Pressure Pulsation Inside Runnersupporting

confidence: 89%

“…It is seen that NACA 4412 has lower peak pressure pulsation value than that of NACA 2412 and NACA 4412 with both clearance gap sizes. Higher pressure fluctuation near clearance gap was previously studied by (Chitrakar, Thapa, Dahlhaug, and Neopane, 2017;Chitrakar, Dahlhaug, and Neopane, 2018). Point 5, Point 3 and Point 1 were taken for the comparison of the effects of leakage flow.…”

Section: Pressure Pulsation Inside Runnermentioning

confidence: 99%

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Numerical Investigation of the Effects of Leakage Flow From Guide Vanes of Francis Turbines using Alternative Clearance Gap Method

2020

JAFM

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Flow around the Guide vanes (GV) in Francis turbine differs with the shape of hydrofoils. The difference in the pressure of fluid travelling to pressure side and suction side of GV contributes to flow behavior. This study presents the numerical technique using alternative clearance gap method to predict the flow around GV and its consequent effect on turbine performance. GV profile has a significant effect on the performance of the turbine with sediment contained fluid flow. In this paper, symmetrical NACA 0012 and cambered NACA 2412, NACA 4412 hydrofoils are studied introducing 0 mm, 2 mm, and 4 mm clearance gaps. Vortex filament can be seen when fluid leaves the clearance gap due to the leakage flow occurring through the gap. The intensity of vortex leaving clearance gap rises with an increase in the size of the clearance gap. However, in the case of asymmetrical GV profile, the velocity of fluid travelling along the vortex compared to that of symmetrical hydrofoil is lower. In case of low specific speed Francis turbines, this vortex is found to be a major reason to erode the runner surface due to high velocity of a sand particle travelling with them. With the alternative clearance gap approach, this paper compares the pressure pulsation downstream of GVs contributed by leakage flow for three NACA profiles, whose frequency is half of blade passing frequency.

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Section: Pressure Pulsation Inside Runnersupporting

confidence: 89%

Section: Pressure Pulsation Inside Runnermentioning

confidence: 99%

Numerical Investigation of the Effects of Leakage Flow From Guide Vanes of Francis Turbines using Alternative Clearance Gap Method

2020

JAFM

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“…Here, k is the turbulence kinetic energy. This expression relates the turbulence kinetic energy with cavitation erosion (Chitrakar, Dahlhaug, & Neopane, 2018). The impact velocity is obtained from the pressure variation, including the mean pressure from the solution of the RANS equations and the fluctuating pressure from the equations for the turbulence closure.…”

Section: Impact Velocitymentioning

confidence: 99%

Isothermal compressible flow solver for prediction of cavitation erosion

Park

Yeo

Rhee

2019

Engineering Applications of Computational Fluid Mechanics

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Cavitation erosion can be observed on hydraulic mechanical devices and has long been studied as a challenging research topic. In this paper, a practical method to predict cavitation erosion was developed. To simulate cavitating flows using computational fluid dynamics (CFD), an isothermal compressible cavitating flow solver was developed using the OpenFOAM toolkit. A cavitation erosion coefficient was proposed as a function of the cavitation and Reynolds numbers. From the simulations, the cavitation erosion coefficients were calculated using metamodeling methods. Finally, the developed practical method of cavitation erosion was applied to a marine propeller. As observed in experiments, cavitation erosion was predicted near the propeller tip.

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“…ere have been a relatively large number of studies on rear guide vanes [20][21][22][23][24][25][26]. Yang et al [27] studied the angle of the IGVs of an axial flow pump.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Influence of Inlet Guide Vanes on the Performance of Shaft Tubular Pumps

Jiao

Sun²,

Song-shan

2021

Shock and Vibration

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To study the influence of inlet guide vanes (IGVs) on the pressure pulsation of a shaft tubular pump, this paper first conducts an experiment to study IGVs. Then, numerical calculations of the shaft tubular pump with and without IGVs are performed to analyze the hydraulic performance and pressure fluctuation characteristics. Finally, the reliability and accuracy of the data are verified by a model test. Numerical simulation results show that with additional IGVs, the pressure pulsation amplitude at the impeller inlet first decreases and then increases under small-flow and design conditions but gradually increases under large-flow conditions. When the IGVs are added to the impeller inlet of the shaft tubular pump, the hydraulic loss in front of the impeller inlet increases, resulting in a significant drop in the head and efficiency of the pump device when the flow rate is less than 1.12 Qd; when the flow rate is greater than 1.12Qd, the head and efficiency of the pump device do not change significantly. IGVs can improve the condition of impeller water inflow and reduce pressure fluctuation on the blade surface.

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Numerical investigation of the effect of leakage flow through erosion-induced clearance gaps of guide vanes on the performance of Francis turbines

Abstract: Neopane (2018) Numerical investigation of the effect of leakage flow through erosion-induced clearance gaps of guide vanes on the performance of Francis turbines, Engineering Applications of Computational

Cited by 26 publications

References 27 publications

Numerical Investigation of the Effects of Leakage Flow From Guide Vanes of Francis Turbines using Alternative Clearance Gap Method

Numerical Investigation of the Effects of Leakage Flow From Guide Vanes of Francis Turbines using Alternative Clearance Gap Method

Isothermal compressible flow solver for prediction of cavitation erosion

Analysis of the Influence of Inlet Guide Vanes on the Performance of Shaft Tubular Pumps

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