The optimization of j-groove shape in the draft tube of a francis turbine to suppress the draft surge

Wei, Qun; Choi, Young Do

doi:10.1088/1757-899x/52/5/052030

Cited by 8 publications

(11 citation statements)

References 7 publications

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“…The water injection technique allows the water jet flow injection from the tip of the crown cone. This technique can successfully mitigate the RVR without affecting the runner and draft tube [25,30]. Similar studies performed by Bosiac et al reported a nearly 30% increase in the pressure recovery coefficient of the draft tube with the water injection technique [27].…”

Section: Introductionsupporting

confidence: 57%

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A Novel Guide Vane System Design to Mitigate Rotating Vortex Rope in High Head Francis Model Turbine

Joy¹,

Raisee²,

Cervantes³

2022

IJFMS

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Guide vanes are a mechanical system used to direct flow in the desired direction. At lower operating conditions, implementing a guide vane system in the draft tube of a hydro-turbine can decrease the excess swirl in the flow and, thus, reduce pressure fluctuations. The present study discusses a numerical methodology to design an effective guide vane system in the draft tube of a high head Francis model turbine. The numerical method is computationally efficient and thus, saves excess computational time and data storage required for parametric analysis of the guide vane system. The aim is to mitigate the 'rotating' vortex rope with minimum additional losses in the turbine. The factors considered for the guide vane system design are a) number of guide vanes, b) chord length, c) span, d) inlet-outlet angles of the guide vanes, and e) their position in the draft tube. The parametric study comprises a) ideal guide vane design and b) realistic guide vane design study. The ideal guide vane design study was with the standalone draft tube domain. The realistic guide vane design study used the passage domains of the distributor, runner, and complete draft tube. From the ideal guide vane design study, a guide vane system with two or three guide vanes of chord 86% of runner radius and leading-edge span of 30% of runner radius effectively mitigates the rotating vortex rope. The system with three guide vanes is the most efficient when placed at some distance below the runner exit with mitigation above 95%

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Section: Introductionsupporting

confidence: 57%

“…Some passive flow control techniques are a) grooving of runner cone [28][29][30][31][32][33], b) exit stay apparatus (ESA) [34], c) fins in the draft tube [35], and d) baffles in the draft tube [36]. The grooving of the runner cone shows some improvements in the flow characteristics but cannot successfully mitigate the RVR.…”

Section: Introductionmentioning

confidence: 99%

A Novel Guide Vane System Design to Mitigate Rotating Vortex Rope in High Head Francis Model Turbine

Joy¹,

Raisee²,

Cervantes³

2022

IJFMS

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“…Moreover, the dimensioning approach for the grooves was unspecified. The study by Wei et al [33,34] claimed that the j-grooves did not completely mitigate the RVR. However, some decrement in the RVR pressure amplitude was reported.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, no specified universal design criteria for such passive mitigation techniques are available. The RVR mitigation studies using exit stay apparatus, fins and j-groove techniques focussed on PL operating conditions [30][31][32][33][34][35][36]. However, their effects on other operating ranges were not investigated in detail.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic Performance of a Francis Turbine with a Variable Draft Tube Guide Vane System to Mitigate Pressure Pulsations

2022

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The present paper demonstrates a proof-of-concept by introducing a variable guide vane system in the draft tube of a high-head Francis model turbine. The aim is to examine the hydraulic performance of the turbine while mitigating the pressure pulsations in the draft tube. The guide vanes can rotate about an axis up to ±45°. The pressure pulsations mitigation studies were performed at lower- and upper-part loads. The hydraulic performance was examined at all operating ranges within the turbine head. There were six guide vane configurations considered between ±45°. The findings demonstrate that the highest efficiency loss with a guide vane configuration that mitigates the pressure pulsations is marginal, with modest improvements at the best efficiency point. The pressure pulsations are 100% mitigated at the lower part load, and there is a maximum decrement in the pressure pulsations up to 80% at the upper part load. The study demonstrates that such a system can improve the operational flexibility of the hydro-turbine by mitigating the pressure pulsations and marginally affecting its hydraulic performance.

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“…There are also var i ous pas sive meth ods de vel oped to deal with the un sta ble flow and pres sure pul sa tions. Two ex am ples are the J-grooves [14,15] and draft tube fins [16]. Al though these two meth ods are ca pa ble of re duc ing the pres sure pul sa tions in the draft tube, their prac ti cal ap pli ca tions are lim ited due to their cost, technics and ef fi ciency.…”

Section: Introductionmentioning

confidence: 99%

The influence of runner cone perforation on the draft tube vortex in Francis hydro-turbine

Li²,

et al. 2018

Therm sci

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The optimization of j-groove shape in the draft tube of a francis turbine to suppress the draft surge

Cited by 8 publications

References 7 publications

A Novel Guide Vane System Design to Mitigate Rotating Vortex Rope in High Head Francis Model Turbine

A Novel Guide Vane System Design to Mitigate Rotating Vortex Rope in High Head Francis Model Turbine

Hydraulic Performance of a Francis Turbine with a Variable Draft Tube Guide Vane System to Mitigate Pressure Pulsations

The influence of runner cone perforation on the draft tube vortex in Francis hydro-turbine

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