Numerical and Experimental Investigation on Unsteady Flow and Hydraulic Radial Force of Low-Head Axial Flow Turbine

Document Type : Regular Article


1 National Research Centre of Pumps, Jiangsu University, Zhenjiang 212013, China

2 Key Laboratory of Fluid and Power Machinery, Ministry of Education, School of Energy and Power Engineering, Xihua University, Chengdu, 610039, China

3 National Research Centre of Pumps, Jiangsu University, Zhenjiang 212013, China 2. Department of Mechanical Engineering, University of Nigeria, Nsukka 410001, Nigeria

4 Department of Mechanical Engineering, University of Nigeria, Nsukka 410001, Nigeria

5 Centre for Sustainable Technologies, Indian Institute of Science, CV Raman Road, Bangalore, India, 560012

6 School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China



Radial force in low-head axial flow turbines (AFTs) is an influential factor in their operational stability. To explore the transient operating behavior of the radial force in low-head AFTs under different blade numbers, transient numeric computations were executed with the shear stress transport (SST) k-w turbulent model. Turbine performance was numerically computed and compared with results from experiments. Furthermore, the unsteady flow field pulsations were experimentally verified by means of pressure sensors. The radial forces on the runners (z = 2, 3, and 4) were each numerically studied in time, frequency, and joint time–frequency fields. The result reveals that the radial force acting on the runner varies with time, since periodic radial forces reflect the vane number on the stay vanes with minimal runner effect. Moreover, the amplitude of the radial forces is directly proportional to the flow rate. Furthermore, the spectral analysis shows that the radial force frequency is close to the blade passing frequency and also increases radially outward since peak values were recorded in this region. Minimal radial force amplitudes were recorded when z = 3, across all flow conditions, making this configuration suitable for smooth and reliable operation. The unstable pressure and force pulses that affect the noise and vibration produced in the turbine are instigated by the flow exchange that occurs between the guide vane and the runner. In order to optimize turbines for increased operational dependability, the acquired data would be crucial references for noise and vibration analytical investigations.


Abo Elyamin, G. R. H., M. A. Bassily, K. Y. Khalil and M. S. Gomaa (2019). Effect of impeller blades number on the performance of a centrifugal pump. Alexandria Engineering Journal 58(1).##
Agostinelli, A., D. Nobles and C. R. Mockridge (1960). An experimental investigation of radial thrust in centrifugal pumps. Journal of Engineering for Power 82(2), 120-125.##
Amiri, K., M. J. Cervantes and B. Mulu (2015). Experimental investigation of the hydraulic loads on the runner of a Kaplan turbine model and the corresponding prototype. Journal of Hydraulic Research 53(4).##
ANSYS CFX-Solver Theory Guide. (2020).
Božić, I. and M. Benišek (2016). An improved formula for determination of secondary energy losses in the runner of Kaplan turbine. Renewable Energy 94, 537-546.##
Byeon, S. S. and Y. J. Kim (2013). Influence of blade number on the flow characteristics in the vertical axis propeller hydro turbine. International Journal of Fluid Machinery and Systems 6(3).##
Celik, I. B., U. Ghia, P. Roache and C. Freitas (2008). Procedure for Estimation and Reporting of Uncertainty Due to Discretization in CFD Applications. Journal of Fluids Engineering, 130(7), 078001.##
Cui, B., J. Li, C. Zhang and Y. Zhang (2020). Analysis of radial force and vibration energy in a centrifugal pump. Mathematical Problems in Engineering 2020.##
Dixon, S. L. and C. A. Hall (2013). Fluid mechanics and thermodynamics of turbomachinery, (7th edition). Butterworth-Heinemann.##
Dörfler, P., M. Sick and A. Coutu (2013). Flow-Induced Pulsation and Vibration in Hydroelectric Machinery. Springer London.##
Eltayesh, A., F. Castellani, M. Burlando, M. Bassily Hanna, A. S. Huzayyin, H. M. El-Batsh and M. Becchetti (2021). Experimental and numerical investigation of the effect of blade number on the aerodynamic performance of a small-scale horizontal axis wind turbine. Alexandria Engineering Journal 60(4).##
Feng, J., F. Benra and H. J. Dohmen (2006). Numerical study on impeller-diffuser interactions with radial gap variation chair of turbomachinery. In The 4th WSEAS International Conference on Fluid Mechanics and Aerodynamics.##
Feng, J., F K. Benra and H. J. Dohmen (2007). Numerical investigation on pressure fluctuations for different configurations of vaned diffuser pumps. International Journal of Rotating Machinery 2007, 1-10.##
Greitzer, E. M., C. S. Tan and M. B. Graf (2004). Internal Flow. Cambridge University Press.##
Haluza, M., P. Rudolf, F. Pochylý and F. Šob (2002). Design of a new low-head turbine. In Proceedings of the XXI-St IAHR Symposium Hydraulic Machinery and Systems.##
Harding, S. F. and M. C. Richmond (2017). Experimental pressure measurements on hydropower turbine runners: a review of experimental methods to quantify hydropower turbine blade pressures at model and prototype scales. Pnnl-26061 48.##
Houde, S., R. Fraser, G. Ciocan and C. Deschênes (2012). Experimental study of the pressure fluctuations on propeller turbine runner blades: part 2, transient conditions. IOP Conference Series: Earth and Environmental Science 15(6).##
Huang, P., D. Appiah, K. Chen, F. Zhang, P. Cao and Q. Hong (2021). Energy dissipation mechanism of a centrifugal pump with entropy generation theory. AIP Advances 11(4), 045208.##
ISO_354. (2003). International Standard International Standard. 61010-1 © Iec:2001 13.##
Iversen, H. W., R. E. Rolling and J. J. Carlson (1960). Volute pressure distribution, radial force on the impeller, and volute mixing losses of a radial flow centrifugal pump. Journal of Engineering for Power 82(2), 136-143.##
Jacquet-Richardet, G., M. Torkhani, P. Cartraud, F. Thouverez, T. Nouri Baranger, M. Herran, C. Gibert, S. Baguet, P. Almeida and L. Peletan (2013). Rotor to stator contacts in turbomachines. Review and application. Mechanical Systems and Signal Processing 40(2), 401-420.##
Javadi, A. and H. Nilsson (2017). Detailed numerical investigation of a Kaplan turbine with rotor-stator interaction using turbulence-resolving simulations. International Journal of Heat and Fluid Flow 63.##
Ketata, A., Z. Driss and M. S. Abid (2020). Impact of blade number on performance, loss and flow characteristics of one mixed flow turbine. Energy 203.##
Kim, H. H., M. Rakibuzzaman, K. Kim and S. H. Suh (2019). Flow and fast fourier transform analyses for tip clearance effect in an operating kaplan turbine. Energies 12(2).##
Krüger, S., Y. A. Bouziad and W. Maurer (n.d.). Pump sump cfd for vertical pump design. In ASME 2009 Fluids Engineering Division Summer Meeting, Vail, Colorado, USA.##
Li, X. B., M. Binama, W. T. Su, W. H. Cai, A. Muhirwa, B. Li and F. C. Li (2020). Runner blade number influencing RPT runner flow characteristics under off-design conditions. Renewable Energy 152.##
Li, Y., I. E. Ohiemi, P. Singh and Y. Sunsheng (2022). Numerical and experimental analysis of pressure fluctuation in axial flow turbine. AIP Advances 12(2), 025122.##
Menter, F. (1993, July 6). Zonal two equation k-w turbulence models for aerodynamic flows. In 23rd Fluid Dynamics, Plasmadynamics, and Lasers Conference.##
Ni, D., N. Zhang, B. Gao, Z. Li and M. Yang (2020). Dynamic measurements on unsteady pressure pulsations and flow distributions in a nuclear reactor coolant pump. Energy 198, 117305.##
Ohiemi, I. E., Y. Sun Sheng, P. Singh and Y. Li (2022). Experimental investigation on the effect of axial gap on performance and unsteady pressure pulsations of low head axial flow hydraulic turbine. Flow Measurement and Instrumentation, 88, 102255.##
Pochylý, F., M. Haluza, P. Rudolf, M. Habán and M. Hudec (2016). Swirl turbine as a variant of low head propeller turbine. In 19th International Seminar on Hydropower Plants: Flexible Operation of Hydropower Plants in the Energy System, Vienna, Austria.##
Rivetti, A., C. Lucino and S. Liscia (2014). Guide vane influence over pressure fluctuation at the discharge ring in a kaplan turbine: experimental assessment. American Journal of Hydropower, Water and Environment Sytems 1, 34-37.##
Rodriguez, C. G., E. Egusquiza and I. F. Santos (2007). Frequencies in the vibration induced by the rotor stator interaction in a centrifugal pump turbine. Journal of Fluids Engineering 129(11), 1428-1435.##
Sang, X., X. Zhou, X. Liu and X. Hao (2017). Radial force within two-stage axial-flow blood pump based on LES. Journal of Vibroengineering 19(2).##
Shamsuddeen, M. M., J. Park, Y. S. Choi and J. H. Kim (2020). Unsteady multi-phase cavitation analysis on the effect of anti-cavity fin installed on a Kaplan turbine runner. Renewable Energy 162.##
Shi, L., Y. Yuan, H. Jiao, F. Tang, L. Cheng, F. Yang, Y. Jin and J. Zhu (2021). Numerical investigation and experiment on pressure pulsation characteristics in a full tubular pump. Renewable Energy 163, 987-1000.##
Singh, P. and F. Nestmann (2009). Experimental optimization of a free vortex propeller runner for micro hydro application. Experimental Thermal and Fluid Science 33(6), 991-1002.##
Singh, P. and F. Nestmann (2010). Exit blade geometry and part-load performance of small axial flow propeller turbines: An experimental investigation. Experimental Thermal and Fluid Science 34(6), 798-811.##
Singh, P. and F. Nestmann (2011). Experimental investigation of the influence of blade height and blade number on the performance of low head axial flow turbines. Renewable Energy 36(1), 272-281.##
Song, X. and C. Liu (2020). Experimental investigation of floor-attached vortex effects on the pressure pulsation at the bottom of the axial flow pump sump. Renewable Energy 145, 2327–2336.##
Song, X. and C. Liu (2019). Experimental investigation of pressure pulsation induced by the floor-attached vortex in an axial flow pump. Advances in Mechanical Engineering 11(3), 1-13.##
Sotoude Haghighi, M. H., S. M. Mirghavami, S. F. Chini and A. Riasi (2019). Developing a method to design and simulation of a very low head axial turbine with adjustable rotor blades. Renewable Energy 135, 266-276.##
Sotoude Haghighi, M. H., S. M. Mirghavami, M. M. Ghorani, A. Riasi and S. F. Chini (2020). A numerical study on the performance of a superhydrophobic coated very low head (VLH) axial hydraulic turbine using entropy generation method. Renewable Energy 147, 409-422.##
Šoukal, J., F. Pochylý, M. Varchola, A. G. Parygin, A. V. Volkov, G. P. Khovanov and A. V. Naumov (2015). Selection of axial hydraulic turbines for low-head microhydropower plants. Thermal Engineering 62(12), 862-867.##
Trivedi, C., M. J. Cervantes, G. Bhupendrakumar and O. G. Dahlhaug (2014). Pressure measurements on a high-head Francis turbine during load acceptance and rejection. Journal of Hydraulic Research 52(2).##
Wilcox, D. C. (1994). Simulation of transition with a two-equation turbulence model. AIAA Journal 32(2).##
Yasuda, T., A. Funakubo, F. Miyawaki, T. Kawamura, T. Higami and Y. Fukui (2001). Influence of static pressure and shear rate on hemolysis of red blood cells. ASAIO Journal 47(4), 351-353.##
Yu-qin, W. and D. Ze-wen (2020). Influence of blade number on flow-induced noise of centrifugal pump based on CFD/CA. Vacuum 172.##
Zhang, M., D. Valentín, C. Valero, M. Egusquiza and E. Egusquiza (2019). Failure investigation of a Kaplan turbine blade. Engineering Failure Analysis 97.##
Zhang, M., D. Valentin, C. Valero, A. Presas, M. Egusquiza and E. Egusquiza (2020). Experimental and numerical investigation on the influence of a large crack on the modal behaviour of a Kaplan turbine blade. Engineering Failure Analysis 109.##
Zhu, X., M. Zhang, G. Zhang and H. Liu (2006). Numerical investigation on hydrodynamics and biocompatibility of a magnetically suspended axial blood pump. ASAIO Journal 52(6), 624-629.##