A Numerical Study of a Pico Hydro Turbine

Pico hydro turbines are suitable for low head applications in power plants since their efficiency is more stable than other turbine types. In some situations, computational fluid dynamics (CFD) has also been utilized as well as experimental studies for the performance prediction of water turbines at a pico scale. Also, CFD methods are getting much closer to real conditions in terms of steady-state with moving references and transient domains with rotor movements. For this purpose, electricity production related to the flow in a PHT was investigated numerically. This study presents six degrees of freedom (6-DOF) and moving reference frame (MRF) methods to predict the maximum conditions of a pico scale two-dimensional turbine by comparing the torque and angular velocities on the runner based on the turbine output power of 1 W determined by an experimental study. Besides, the effect of the torque, angular velocity, tip speed ratio, and turbine body profile was investigated comprehensively. In this regard, MRF and 6-DOF methods were performed to validate and compare the numerical model with the experimental results. Also, the results obtained from 6-DOF and MRF methods were compared to experimental study. It is concluded that PHT is generating 0.3 W power under 6.47 rad/s angular velocity with 6-DOF method, however; this value corresponds to 31.4 rad/s angular velocity against 1 W with the MRF method. Also, the maximum velocity of the turbine was 6.1 m/s according to the simulation result. It is accepted that the turbine maximum velocity inlet was 0.53 m/s based on the experimental study. As a conclusion, numerical results for the pico hydro turbine were reasonable taking the experimental study into account. It is also concluded that there is a tip speed ratio of 2.36 with the MRF method and 0.48 with the 6-DOF method between water tangential velocity and runner velocity for the turbine model.

Keywords:

Pico hydro turbine, moving reference frame, 6-DOF, turbine power output, tip speed ratio,

PDF

___

[1] B. R. Cobb, K. V. Sharp, "Impulse (Turgo and Pelton) turbine performance characteristics and their impact on pico-hydro installations," Renewable Energy, vol. 50, pp. 959–964, 2013.
[2] L. Alveyro, F. Jose, S. Aida, "Performance improvement of a 500-kW Francis turbine based on CFD," vol. 96, 2016.
[3] N. Thakur, A. Biswas, Y. Kumar, M. Basumatary, "CFD analysis of performance improvement of the Savonius water turbine by using an impinging jet duct design," Chinese Journal of Chemical Engineering., vol. 27, no. 4, pp. 794–801, 2019.
[4] S. Chichkhede, V. Verma, V. K. Gaba, S. Bhowmick, "A Simulation Based Study of Flow Velocities across Cross Flow Turbine at Different Nozzle Openings," Procedia Technology., vol. 25, pp. 974–981, 2016.
[5] D. Jiyun, S. Zhicheng, Y. Hongxing, "Performance enhancement of an inline cross-ow hydro turbine for power supply to water leakage monitoring system," Energy Procedia, vol. 145, pp. 363–367, 2018.
[6] S. J. Kim, Y. S. Choi, Y. Cho, J. W. Choi, J. H. Kim, "Effect of blade thickness on the hydraulic performance of a Francis hydro turbine model," Renewable. Energy, vol. 134, pp. 807–817, 2019.
[7] J. F. Wang, J. Piechna, N. Müller, “A novel design of composite water turbine using CFD,” Journal of Hydrodynamics, vol. 24, no. 1, pp. 11–16, 2012.
[8] N. Acharya, C. G. Kim, B. Thapa, Y. H. Lee, "Numerical analysis and performance enhancement of a cross-flow hydro turbine," Renewable Energy, vol. 80, pp. 819–826, 2015.
[9] G. Birhanu Oliy, "Design and Computational Fluid Dynamic Simulation Study of High Efficiency Cross Flow Hydro-power Turbine," International Journal of Science, Technology and Society., vol. 5, no. 4, p. 120, 2017.
[10] R. K. Ranjan, N. Alom, J. Singh, B. K. Sarkar, "Performance investigations of cross flow hydro turbine with the variation of blade and nozzle entry arc angle," Energy Conversion and Management vol. 182, no. January, pp. 41–50, 2019.
[11] D. A. Makarim, D. D. D. P. Tjahjana, S. I. Cahyono, S. A. Mazlan, "Performance investigation of the crossflow water turbine by using CFD," AIP Conference Proceedings, vol. 2097, 2019.
[12] A. P. Prakoso, Warjito, A. I. Siswantara, Budiarso, D. Adanta, "Comparison between 6-DOF UDF and moving mesh approaches in CFD methods for predicting cross-flow pico-hydro turbine performance," CFD Letters., vol. 11, no. 6, pp. 86–96, 2019.
[13] X. Wang, X. Luo, B. Zhuang, W. Yu, H. Xu, "6-DOF numerical simulation of the vertical-axis water turbine," ASME-JSME-KSME 2011 Joint Fluids Engineering. Conferenes. AJK 2011, vol. 1, no. PARTS A, B, C, D, pp. 673–678, 2011.