Nozzle Entry Effects and Cavitation Inception in Crossflow Hydroturbines

  • R. C. Adhikari
  • D. H. WoodEmail author
Conference paper
Part of the Springer Proceedings in Energy book series (SPE)


Crossflow hydroturbines are simple and cheap to manufacture. This work is part of a program to improve the design methodology of small crossflow hydroturbines for remote power systems in developing countries. Adhikari and Wood (2018) showed that the exit arc—the circumferential extent of the flow exiting the runner—is typically half the length of the entry arc, θs, of the flow entering the runner. Negative gauge pressures are thus required in the exiting flow to achieve high efficiency. Here, we investigate increasing θs to reduce the negative pressures and the influence on cavitation which begins on the blades near the exit. The influence of θs is studied using computational fluid dynamics simulation of two turbines whose performance has been measured experimentally. No evidence of cavitation was found in the 0.53 kW turbine (efficiency η = 88%, flow rate Q = 46 lps, and head H = 1.337 m) at any operating speed, whereas significant cavitation was found at maximum efficiency (η = 91%) in the improved design of the 7 kW turbine (original η = 69%, Q = 105 lps, and H = 10 m). The extent of cavitation decreased as θs was increased but this also decreased η from 91% to 87%. Changes in radius ratio and inner blade angle decreased significantly the size of cavitation inception region with only a small decrease in maximum efficiency. Finally, redesigning the turbine for reduced H = 8 m and Q = 94 lps avoided cavitation while achieving a similar maximum efficiency of 89.3%. Nevertheless, it may be possible to avoid cavitation through investigation of an optimum combination of geometrical parameters but this would require a considerable computational effort which probably should be guided by experiment.


Crossflow turbine Efficiency Entry arc RANS simulation Cavitation inception 



Runner entry flow angle (rad or degrees)


Outer blade angle (rad or degrees)


Inner blade angle (rad or degrees)


Turbine head (m)


Nozzle throat (m)


Nozzle rear wall from the runner tip, R(θ)–R1, (m)


Number of blades


Flow rate through turbine (lps)


Maximum (design) flow rate (lps)


Radius of nozzle rear wall (m)


Outer radius of the runner (m)


Inner radius of the runner (m)


Local static pressure (Pa)


Saturated vapor pressure (Pa)


Nozzle inlet velocity (m/s)


Nozzle and runner width (m)


Turbine power (kW)


Runner angular speed (m/s)


Entry arc (rad or degrees)


Turbine efficiency (%)


Water density (kg/m3)



The authors acknowledge the funding from the Schulich Research Chair in Renewable Energy at the University of Calgary, Canada. We also acknowledge WestGrid Canada for providing high-performance computers to perform flow simulations.


  1. Adhikari, R.: Design improvement of crossflow hydro turbine. Ph.D. thesis University of Calgary, Canada (2016)Google Scholar
  2. Adhikari, R., Wood, D.: A new nozzle design methodology for high efficiency crossflow hydro turbines. Energy. Sustain. Dev. 41, 139–148 (2017)CrossRefGoogle Scholar
  3. Adhikari, R., Wood, D.: Computational analysis of a double-nozzle crossflow turbines. Energies, (submitted) (2018)Google Scholar
  4. Adhikari, R.C., Vaz, J., Wood, D.: Cavitation inception in crossflow hydro turbines. Energies 9, 237–248 (2016)CrossRefGoogle Scholar
  5. Adhikari, R.C., Wood, D.: Design of high efficiency crossflow turbines: review and extension. Energies 11, 267 (2018). Scholar
  6. Dakers, A., Martin, G.: Development of a simple cross-flow water turbine for rural use. In: Agricultural Engineering Conference 1982: Resources, Efficient Use and Conservation; Preprints of Papers, p. 35. Institution of Engineers, Australia (1982)Google Scholar
  7. Desai, V.R.: A Parametric study of the cross-flow turbine performance. Ph.D. thesis Clemson University, USA (1993)Google Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Department of Mechanical and Manufacturing EngineeringUniversity of CalgaryCalgaryCanada

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