Enhancing hydropower sustainability through air injection: experimental reduction of sediment erosion in Francis turbine guide vanes

Prashant Dhiman, Abhiraj Chaudhary, Niteesh Rautela, Ashish Karn

Abstract


Hydropower is a reliable and renewable source of energy, but plants operating in sediment-laden rivers, particularly in Himalayan regions, frequently experience severe erosive wear of turbine components. Sediment-induced material degradation of guide vanes, runner blades, and other flow-controlling parts increases maintenance frequency, downtime, and lifecycle cost. This study experimentally investigates air injection as a mitigation technique for improving hydropower sustainability through reduction of sediment erosion in Francis turbine guide vanes. Experiments were performed using a specially developed rotary disc apparatus with guide vane specimens based on the NACA 4412 profile. The effects of sediment concentration (60,000, 80,000, and 100,000 ppm), angle of attack (0°, 15°, and 30°), and air flow rate were systematically evaluated. Results show that air injection significantly decreases material loss compared with non-aerated conditions, with erosion reduction ranging from 32% to 51%. Higher air flow rates provided greater protection, indicating that the injected air forms an effective buffer layer that reduces particle-surface interaction. The findings demonstrate that air injection can enhance component service life, lower maintenance demand, and support more sustainable operation of sediment-prone hydropower plants.

 

Received: 24 April 2026

Accepted: 08 June 2026

Published: 28 June 2026


Keywords


Sediment Erosion, Rotary Disc Apparatus (RDA), Guide Vanes, Downtime, Air-injection

Full Text:

PDF

References


G. Ardizzon, G. Cavazzini, and G. Pavesi, “A new generation of small hydro and pumped-hydro power plants: Advances and future challenges,” Renewable and Sustainable Energy Reviews, vol. 31, pp. 746–761, Mar. 2014, doi: https://doi.org/10.1016/j.rser.2013.12.043.

U. Dorji and R. Ghomashchi, “Hydro turbine failure mechanisms: An overview,” Engineering Failure Analysis, vol. 44, pp. 136–147, Sep. 2014, doi: https://doi.org/10.1016/j.engfailanal.2014.04.013.

S. Gautam, H. P. Neopane, N. Acharya, S. Chitrakar, B. S. Thapa, and B. Zhu, “Sediment erosion in low specific speed francis turbines: A case study on effects and causes,” Wear, vol. 442–443, p. 203152, Feb. 2020, doi: https://doi.org/10.1016/j.wear.2019.203152.

Sailesh Chitrakar, Hari Prasad Neopane, and Ole Gunnar Dahlhaug, “A Review on Sediment Erosion Challenges in Hydraulic Turbines,” InTech eBooks, Apr. 2018, doi: https://doi.org/10.5772/intechopen.70468.

M. K. Padhy and R. P. Saini, “A review on silt erosion in hydro turbines,” Renewable and Sustainable Energy Reviews, vol. 12, no. 7, pp. 1974–1987, Sep. 2008, doi: https://doi.org/10.1016/j.rser.2007.01.025.

C. Hauer et al., “State of the art, shortcomings and future challenges for a sustainable sediment management in hydropower: A review,” Renewable and Sustainable Energy Reviews, vol. 98, pp. 40–55, Dec. 2018, doi: https://doi.org/10.1016/j.rser.2018.08.031.

S. Mishra, S. K. Singal, and D.K. Khatod, “Design of desilting tank for small hydropower projects - A review,” Water and Energy International., vol. 68, no. 4, pp. 32–36, Apr. 2011, Available: https://www.researchgate.net/publication/294328024_Design_of_desilting_tank_for_small_hydropower_projects_-_A_review

G. Singh and A. Kumar, “Performance evaluation of desilting basins of small hydropower projects,” ISH Journal of Hydraulic Engineering, vol. 22, no. 2, pp. 135–141, Jan. 2016, doi: https://doi.org/10.1080/09715010.2015.1094750.

V. Almeida et al., “Approach to sediment monitoring in Hydro Power Plant,” IOP Conference Series: Earth and Environmental Science, vol. 1079, no. 1, p. 012062, Sep. 2022, doi: https://doi.org/10.1088/1755-1315/1079/1/012062.

A. Kr. Rai and A. Kumar, “Sediment monitoring for hydro-abrasive erosion : A field study from Himalayas, India,” International Journal of Fluid Machinery and Systems, vol. 10, no. 2, pp. 146–153, Jun. 2017, doi: https://doi.org/10.5293/ijfms.2017.10.2.146.

M. B. Bishwakarma and H. Støle, “Real-time sediment monitoring in hydropower plants,” Journal of Hydraulic Research, vol. 46, no. 2, pp. 282–288, Mar. 2008, doi: https://doi.org/10.1080/00221686.2008.9521862.

D. Felix, I. Albayrak, and R. M. Boes, “Continuous measurement of suspended sediment concentration: Discussion of four techniques,” Measurement, vol. 89, pp. 44–47, Jul. 2016, doi: https://doi.org/10.1016/j.measurement.2016.03.066.

R. Kumar, S. Bhandari, and A. Goyal, “Synergistic effect of Al 2 O 3 /TiO 2 reinforcements on slurry erosion performance of nickel-based composite coatings,” Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, vol. 232, no. 8, pp. 974–986, Oct. 2017, doi: https://doi.org/10.1177/1350650117736487.

V. Sharma, M. Kaur, and S. Bhandari, “Slurry erosion performance study of high velocity flame sprayed Ni–Al2O3 coating under hydro accelerated conditions,” Materials Research Express, vol. 6, no. 7, p. 076436, Apr. 2019, doi: https://doi.org/10.1088/2053-1591/ab1927.

G. Prashar, H. Vasudev, and L. Thakur, “Performance of different coating materials against slurry erosion failure in hydrodynamic turbines: A review,” Engineering Failure Analysis, vol. 115, p. 104622, Sep. 2020, doi: https://doi.org/10.1016/j.engfailanal.2020.104622.

K. R.K., K. M., S. S., and A. K. S., “A pragmatic approach and quantitative assessment of silt erosion characteristics of HVOF and HVAF processed WC-CoCr coatings and 16Cr5Ni steel for hydro turbine applications,” Materials & Design, vol. 132, pp. 79–95, Oct. 2017, doi: https://doi.org/10.1016/j.matdes.2017.06.046.

S. A. Romo, J. F. Santa, J. E. Giraldo, and A. Toro, “Cavitation and high-velocity slurry erosion resistance of welded Stellite 6 alloy,” Tribology International, vol. 47, pp. 16–24, Oct. 2011, doi: https://doi.org/10.1016/j.triboint.2011.10.003.

J. F. Santa, L. A. Espitia, J. A. Blanco, S. A. Romo, and A. Toro, “Slurry and cavitation erosion resistance of thermal spray coatings,” Wear, vol. 267, no. 1–4, pp. 160–167, Jun. 2009, doi: https://doi.org/10.1016/j.wear.2009.01.018.

D. K. Goyal, H. Singh, H. Kumar, and V. Sahni, “Slurry Erosive Wear Evaluation of HVOF-Spray Cr2O3 Coating on Some Turbine Steels,” Journal of Thermal Spray Technology, vol. 21, no. 5, pp. 838–851, Jun. 2012, doi: https://doi.org/10.1007/s11666-012-9795-5.

Z. Chen and Y.-D. Choi, “Influence of air supply on the performance and internal flow characteristics of a cross flow turbine,” Renewable Energy, vol. 79, pp. 103–110, Jul. 2015, doi: https://doi.org/10.1016/j.renene.2014.08.024.

K. Kumar and R. P. Saini, “A review on operation and maintenance of hydropower plants,” Sustainable Energy Technologies and Assessments, vol. 49, no. 101704, p. 101704, Feb. 2022, doi: https://doi.org/10.1016/j.seta.2021.101704.

P. K. Sanjeevaiah and A. Karn, “Enhancement of dissolved oxygen level in the reservoir downstream using air injection techniques in hydroturbines: A review,” Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 46, no. 1, pp. 9935–9954, Jul. 2024, doi: https://doi.org/10.1080/15567036.2024.2382325.

R. E. A. Arndt, C. R. Ellis, and S. Paul, “Preliminary investigation of the use of air injection to mitigate cavitation erosion,” Journal of Fluids Engineering, Transactions of the ASME, vol. 11, no. 3, pp. 498–504, 1995, doi: https://doi.org/10.1115/1.2817290.

A. Karn, “Characterization of Bubbly Flow Systems: A Review,” International Journal Of Petrochemical Science & Engineering, vol. 2, no. 6, Jul. 2017, doi: https://doi.org/10.15406/ipcse.2017.02.00053.

A. Karn, R. De, J. Hong, and R. E. A. Arndt, “Closure mechanisms of ventilated supercavities under steady and unsteady flows,” Journal of Physics: Conference Series, vol. 656, p. 012145, Dec. 2015, doi: https://doi.org/10.1088/1742-6596/656/1/012145.

A. Karn, S. Shao, R. E. A. Arndt, and J. Hong, “Bubble coalescence and breakup in turbulent bubbly wake of a ventilated hydrofoil,” Experimental thermal and fluid science, vol. 70, pp. 397–407, Jan. 2016, doi: https://doi.org/10.1016/j.expthermflusci.2015.10.003.

A. Karn, C. R. Ellis, J. Hong, and Roger, “Investigations into the turbulent bubbly wake of a ventilated hydrofoil: Moving toward improved turbine aeration techniques,” Experimental Thermal and Fluid Science, vol. 64, pp. 186–195, Jun. 2015, doi: https://doi.org/10.1016/j.expthermflusci.2014.12.011.

M. S. Sadeq and M. S. Kassim, “Experimental investigation of axial-flow turbine performance using water and oil: effects of rotation speed, blade count, and oil pre-heating,” Renewable Energy and Sustainable Development, vol. 11, no. 2, p. 301, Sep. 2025, doi: https://doi.org/10.21622/resd.2025.11.2.1445.

P. Dhiman, A. Bhat, and A. Karn, “The Efficacy of Air Injection in Mitigating Silt Erosion on Hydroturbine Blades: A Computational Study,” Lecture Notes in Civil Engineering, pp. 437–444, 2024, doi: https://doi.org/10.1007/978-981-99-6616-5_49.

P. Dhiman, A. Bhat, and A. Karn, “Multiphase Flow Simulations to Explore Novel Technique of Air Injection to Mitigate Silt Erosion in Hydro Turbines,” Journal of Applied Fluid Mechanics, vol. 18, no. 2, Feb. 2025, doi: https://doi.org/10.47176/jafm.18.2.2735.

P. Dhiman, V. P. Singh, and A. Karn, “Experimental and computational analysis of air injection as a mitigation technique for silt erosion in hydro turbines,” Renewable Energy and Sustainable Development, vol. 10, no. 2, p. 345, Nov. 2024, doi: https://doi.org/10.21622/resd.2024.10.2.1054.

R. Koirala, B. Thapa, H. P. Neopane, and B. Zhu, “A review on flow and sediment erosion in guide vanes of Francis turbines,” Renewable and Sustainable Energy Reviews, vol. 75, pp. 1054–1065, Aug. 2017, doi: https://doi.org/10.1016/j.rser.2016.11.085.

R. Koirala, B. Thapa, H. P. Neopane, B. Zhu, and B. Chhetry, “Sediment erosion in guide vanes of Francis turbine: A case study of Kaligandaki Hydropower Plant, Nepal,” Wear, vol. 362–363, pp. 53–60, Sep. 2016, doi: https://doi.org/10.1016/j.wear.2016.05.013.

R. Koirala, H. P. Neopane, O. Shrestha, B. Zhu, and B. Thapa, “Selection of guide vane profile for erosion handling in Francis turbines,” Renewable Energy, vol. 112, pp. 328–336, Nov. 2017, doi: https://doi.org/10.1016/j.renene.2017.05.033.

E. Quaranta and P. Davies, “Emerging and Innovative Materials for Hydropower Engineering Applications: Turbines, Bearings, Sealing, Dams and Waterways, and Ocean Power,” Engineering, vol. 8, Sep. 2021, doi: https://doi.org/10.1016/j.eng.2021.06.025.

O. Shrestha, H. P. Neopane, B. Thapa, Y.-H. Lee, and A. Kapali, “Rotating Disc Apparatus and its application to estimate sediment erosion in Hydro turbines,” International Journal of Scientific Research in Science and Technology, pp. 348–358, Dec. 2021, doi: https://doi.org/10.32628/ijsrst218616.

C. Liu, W. Wei, Q. Yan, and N. R. Morgan, “Design of experiments to investigate blade geometric effects on the hydrodynamic performance of torque converters,” Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering, vol. 233, no. 2, pp. 276–291, Dec. 2017, doi: https://doi.org/10.1177/0954407017742573.

A. Jankovic, G. Chaudhary, and F. Goia, “Designing the design of experiments (DOE) – An investigation on the influence of different factorial designs on the characterization of complex systems,” Energy and Buildings, vol. 250, no. 111298, p. 111298, Nov. 2021, doi: https://doi.org/10.1016/j.enbuild.2021.111298.

S. J. W. Klein and E. L. B. Fox, “A review of small hydropower performance and cost,” Renewable and Sustainable Energy Reviews, vol. 169, p. 112898, Nov. 2022, doi: https://doi.org/10.1016/j.rser.2022.112898.

S. Sangal, M. K. Singhal, and R. P. Saini, “Hydro-abrasive erosion in hydro turbines: a review,” International Journal of Green Energy, vol. 15, no. 4, pp. 232–253, Feb. 2018, doi: https://doi.org/10.1080/15435075.2018.1431546.

N. Shrivastava and A. K. Rai, “Hydro-abrasive erosion in Pelton turbines: Comprehensive review and future outlook,” Renewable and Sustainable Energy Reviews, vol. 207, p. 114957, Jan. 2025, doi: https://doi.org/10.1016/j.rser.2024.114957.




DOI: https://dx.doi.org/10.21622/resd.2026.12.1.2100

Refbacks

  • There are currently no refbacks.


Copyright (c) 2026 Prashant Dhiman, Niteesh Rautela, Abhiraj Chaudhary, Ashish Karn

Renewable Energy and Sustainable Development

E-ISSN: 2356-8569

P-ISSN: 2356-8518

 

Published by:

Academy Publishing Center (APC)

Arab Academy for Science, Technology and Maritime Transport (AASTMT)

Alexandria, Egypt

resd@aast.edu