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Aerothermal Investigation of the Effect of Endwall Structures on Radial Turbine Heat Losses

Author

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  • M. A. Khader

    (Department of Mechanical Engineering, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK)

  • A. I. Sayma

    (Department of Mechanical Engineering, Brunel University London, Kingston Lane, London UB8 3PH, UK)

  • Jafar Al-Zaili

    (Department of Engineering, City St George’s, University of London, Northampton Square, London EC1V 0HB, UK)

  • Mohsen Ghavami

    (Department of Engineering, City St George’s, University of London, Northampton Square, London EC1V 0HB, UK)

  • Hongwei Wu

    (Department of Mechanical Engineering, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK)

Abstract

This paper presents a detailed numerical investigation of the effect of hub-mounted riblets on the thermal and aerodynamic performance of a radial turbine rotor. While prior studies have shown that riblets reduce wall shear stress and improve aerodynamic efficiency, their influence on heat transfer and thermal losses remains underexplored. Using numerical simulations, this study examines the heat transfer characteristics within the rotor passage, comparing ribbed and smooth hub configurations under the same operating conditions. Results reveal that although riblets reduce frictional drag, they also enhance convective heat transfer—leading to a 6% increase in the heat transfer coefficient at the hub and 2.8% at the blade surfaces. This intensification of heat transfer results in a 4.3% rise in overall thermal losses, counteracting some of the aerodynamic gains. The findings provide new insights into the thermofluidic implications of surface modifications in turbomachinery and emphasise the importance of considering surface finish not only for aerodynamic optimisation but also for thermal efficiency. These results can inform future turbine design and manufacturing practices aimed at controlling surface roughness to minimise heat loss.

Suggested Citation

  • M. A. Khader & A. I. Sayma & Jafar Al-Zaili & Mohsen Ghavami & Hongwei Wu, 2025. "Aerothermal Investigation of the Effect of Endwall Structures on Radial Turbine Heat Losses," Energies, MDPI, vol. 18(16), pages 1-20, August.
    • Handle: RePEc:gam:jeners:v:18:y:2025:i:16:p:4366-:d:1725888
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    References listed on IDEAS

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    1. Roberta De Robbio & Maria Cristina Cameretti & Salvatore Agizza, 2023. "Design and Thermo-Economic Analysis of an Integrated Solar Field Micro Gas Turbine Biomass Gasifier and Organic Rankine Cycle System," Energies, MDPI, vol. 16(20), pages 1-25, October.
    2. Fabrizio Reale & Patrizio Massoli, 2024. "A Hybrid Energy System Based on Externally Fired Micro Gas Turbines, Waste Heat Recovery and Gasification Systems: An Energetic and Exergetic Performance Analysis," Energies, MDPI, vol. 17(15), pages 1-16, July.
    3. Mateusz Proniewicz & Karolina Petela & Christine Mounaïm-Rousselle & Mirko R. Bothien & Andrea Gruber & Yong Fan & Minhyeok Lee & Andrzej Szlęk, 2025. "Preliminary Comparison of Ammonia- and Natural Gas-Fueled Micro-Gas Turbine Systems in Heat-Driven CHP for a Small Residential Community," Energies, MDPI, vol. 18(15), pages 1-23, August.
    4. Reyhaneh Banihabib & Mohsen Assadi, 2022. "The Role of Micro Gas Turbines in Energy Transition," Energies, MDPI, vol. 15(21), pages 1-22, October.
    5. A. H. Samitha Weerakoon & Mohsen Assadi, 2024. "Micro Gas Turbines in the Global Energy Landscape: Bridging the Techno-Economic Gap with Comparative and Adaptive Insights from Internal Combustion Engines and Renewable Energy Sources," Energies, MDPI, vol. 17(21), pages 1-31, October.
    6. Mahmoud A. Khader & Mohsen Ghavami & Jafar Al-Zaili & Abdulnaser I. Sayma, 2021. "Heat Transfer Effect on Micro Gas Turbine Performance for Solar Power Applications," Energies, MDPI, vol. 14(20), pages 1-15, October.
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