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ABSTRACT
The present paper aims to evaluate the empirical as well as analytical approaches normally adopted for the computation of desilting efficiency of pressure type desilting basin used in hydroelectric project (H.E.P) constructed in Himalayan regions. Due to limited availability of space and steep topography, pressure type desilting basins are mostly preferred. Four significant projects in the Himalayan region are chosen for the performance analysis of desilting chamber: Kholongchhu H.E.P, Mangdechhu H.E.P, Teesta Stage-IV H.E.P, and Punatsangchhu Stage-II. Theoretical efficiency (function of shear velocity (µ*) and mixing coefficient (ℇ)) of all the four projects were computed by existing as well as modified formulae as suggested by Camp-Dobbin (1946) and Sinha and Singh (2019), respectively. It is concluded that particle removal efficiency obtained from model studies for these four hydropower projects and that computed by Camp-Dobbin’s approach (1946) are in close agreement. The outcome of this paper suggests that out of six commonly used approaches, the approach recommended by Camp-Dobbin (1946) is most suitable methodology to design the desilting basin in Himalayan region. It is envisaged that the present study will enable the designer to select a most appropriate approach to design an efficient and suitable desilting basin for construction in Himalayan region.
Acknowledgements
The second author [Aditya Thakare] is grateful to CWPRS, Pune, for providing necessary facility to carry out the present experimental study and conveys thanks to National Institute of Technology, Kurukshetra for giving necessary accommodation to carry out research work at CWPRS with institute scholarship.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author.
Notations
| ach | = | Approach conduit cross-sectional area (m2) |
| A | = | Cross-sectional/Flow area (m2) |
| B* | = | Non dimensional length |
| b | = | Width of approach channel (m) |
| β | = | Rouse number |
| D | = | Depth of desilting basin (m) |
| D* | = | Non dimensional depth |
| ℇ | = | Mixing coefficient (m2/s) |
| g | = | Acceleration due to gravity (m/s2) |
| h | = | Depth of flow in approach channel (m) |
| H.E.P | = | Hydroelectric project |
| ĸ | = | Von Karman constant |
| L | = | Desilting basin length (m) |
| L* | = | Non dimensional length |
| Lr | = | Scale Ratio |
| λ | = | Velikanov’s function |
| n | = | Manning’s roughness coefficient |
| ƞ | = | Desilting efficiency |
| ƞd | = | Flushing efficiency |
| Q | = | Discharge (m3/s) |
| R | = | Hydraulic radius (m) |
| U | = | Flow through velocity (m/s) |
| µ* | = | Shear Velocity (m/s) |
| V | = | Average forward velocity of desilting basin |
| Vr | = | Velocity ratio |
| Vp | = | Velocity in prototype (m/s) |
| Vm | = | Velocity in prototype (m/s) |
| w | = | Settling velocity (m/s) |
| W | = | Width of basin (m) |
| we | = | Effective fall velocity (m/s) |
| wo | = | Overflow rate (m/s) |