Using CFD in the analysis of Impulse turbines with a focus on the high capacity Turgo

Transcription

1 Using CFD in the analysis of Impulse turbines with a focus on the high capacity Turgo Speaker Name: Shaun Benzon Position: PhD Student (Lancaster University) Company: Gilkes Country: England, UK

2 Overview Introduction CFD Methodologies Lagrangian Methods Eulerian Methods The Turgo Turbine CFD analysis of the Turgo Turbine

3 Introduction CFD covers middle ground between physical testing and on paper analysis CFD applies to many branches of engineering o o o o o Energy Automotive Aviation Naval Etc Must be coupled with understanding of the underlying physics

4 CFD Methodologies Eulerian methods Finite control volume fixed in space Infinitesimally small element fixed in space Finite control volume moving with the flow (fixed mass) Lagrangian Methods Infinitesimally small element moving with the flow (fixed mass)

5 Lagrangian Methods Mesh-less Lagrangian methods- particles moving with flow SPH- Smooth Particle Hydrodynamics most popular [1] Originally designed for measuring astrophysical phenomena in the 1970 s [2]. Its application to engineering was discovered in the 1990 s-2000 s and is currently being used to simulate a variety of highly distorting fluids and solids [3]. The SPH European Interest Community (SPHERIC) was developed in 2005 to facilitate the spread of SPH methods

6 Lagrangian Methods SPH Methods for flow predictions at a Turgo Comparative study by P. Koukouvinis et al. in 2011 between standard SPH and commercial CFD package (ANSYS Fluent ) [4]. Showed good average however SPH was less stable with scatter. Only measures torque on inside surface of blades.

7 Eulerian Methods Solve governing equations at fixed locations in domain. Requires fine mesh in areas of high gradients can result in high computational cost Shown good agreement with experimental results for Pelton turbines [5, 6] using homogeneous multiphase models with k-ω SST turbulence models [7] Can easily measure the torque on either side of the runner blades

8 Eulerian Methods Numerical Prediction of Pelton Efficiency Study carried out by D. Jošt, P. Mežnar and A. Lipej in 2010 comparing CFD to experimental results for a Pelton using ANSYS CFX-12.1 with k-ω SST turbulence model and free surface flow using two-phase homogeneous modelling [7].

9 The Turgo Turbine The Turgo impulse turbine was invented by Eric Crewdson, Managing Director of Gilkes, in 1919 and a patent was awarded in A paper was presented in 1922 at the Institution of Civil Engineers: Design and Performance of a New Impulse Water-Turbine (Crewdson, 1922) [8,9]. Drawing of the 1920 Crewdson Turgo design showing the inlet plane and cut section with the jet trace on the inlet wheel plane shaded [9] Elevation and plan view showing the 1920 Crewdson design of the Turgo machine [9]

10 The Turgo Turbine The 150HP (at full load) turbine used in the initial tests was tested using a 65kW continuous current compoundwound interpole generator, set up for 220V at rpm [9]. A similar turbine of the same capacity was later tested by Dr A. H. Gibson of Manchester University showing a maximum efficiency of 83.5% under a head of 200 feet, producing 106HP, at 640rpm (Crewdson, 1922) [9].

11 PERFORMANCE ENVELOPE [10] Head Range: up to 300m [11] Power Output: up to 10MW The Turgo Turbine

12 DESIGN LAYOUT [10] The Turgo Turbine

13 The Turgo Turbine The Turgo impulse turbine was developed to provide a simple impulse type machine with a higher specific speed than a Pelton by inclining the jet to the runner face [8, 10]. The first Turgo turbine was installed in Since then Gilkes have supplied over 900 Turgo turbines producing a total of 300 MW to over 80 countries. Many of the original units are still in operation today [8, 10].

14 CFD analysis of the Turgo Turbine Using Eulerian Method 1. Mesh Independence Study 2. Design Optimisation

15 CFD analysis of the Turgo Turbine Mesh Independence Study Mesh sizing for 2 bladed mesh study- 2.67M elements

16 CFD analysis of the Turgo Turbine Mesh Independence Study

17 Design Optimisation CFD analysis of the Turgo Turbine

18 CFD analysis of the Turgo Turbine Design Modification Blade geometry is split into a series of control curves which can be used to adjust the shape of the runner. The changes can be based on analysis from flow visualisation or using a systematic analysis such as a Design of Experiments study.

19 CFD analysis of the Turgo Turbine Mesh Generation Mesh sizing and quality is very important in order to capture the flow correctly. Inflation layers wrapping around the trailing edge with the maximum prism angle set to 180deg

20 CFD analysis of the Turgo Turbine Pre-processing Solver settings e.g. timestep Turbulence model e.g. k-ω SST Multiphase model e.g. Homogeneous Fluid pairing i.e. surface tension Interphase transfer e.g. Free-surface Boundary conditions- e.g. wall conditions

21 CFD analysis of the Turgo Turbine Post-processing Pressure profiles Velocity profiles

22 Post-processing CFD analysis of the Turgo Turbine Inlet view Outlet view

23 References 1. Marongiu, J., C., Leboeuf, F. and Parkinson, E., Numerical simulation of the flow in a Pelton turbine using the meshless method smoothed particle hydrodynamics: a new simple solid boundary treatment. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy Gingold, R. A. and Monaghan, J. J., Smoothed Particle Hydrodynamics: Theory and Application to non- Spherical Stars. Monthly Notices of the Royal Astronomical Society, vol. 181, Nov. 1977, p SPH European Research Interest Community, SPHERIC Home Page. [online] Available at: < [Accessed 15 February 2012] 4. Rafiee, A., S. Cummins, et al. (2012). "Comparative study on the accuracy and stability of SPH schemes in simulating energetic free-surface flows." European Journal of Mechanics - B/Fluids 36(0): Koukouvinis, P. K., J. S. Anagnostopoulos, et al. (2011). SPH Method used for Flow Predictions at aturgo Impulse Turbine: Comparison with Fluent. World Academy of Science, Engineering and Technology Zoppé, B., Pellone, C., Maitre, T. and Leroy, P., Flow analysis inside a Pelton turbine bucket. Trans. ASME J. Turbomach., 2006, 128, Jošt, D., Mežnar, P. and Lipej, A., Numerical Prediction of Efficiency, Cavitation and Unsteady Phenomena in Water Turbines. Proceedings of the 9th Biennial ASME Conference on Engineering Systems Design and Analysis. ESDA08. July 7-9, 2008, Haifa, Israel. 8. Benzon, D., Aggidis, G., Martin, J., Scott, J., Watson, A., State of the art & current research on Turgo impulse turbines. Clean Power Africa-Africa Utility Week, th May 2013 Conference, Cape Town, South Africa. Esi-Africa Online Power Journal [accessed 24/04/14] 9. Crewdson, E. (1922). Design and Performance of a New Impulse Water-Turbine. Minutes of Proceedings of the Institution of Civil Engineers, The Institution of Civil Engineers. 10. Gilbert Gilkes and Gordon Ltd, Gilkes Hydropower Brochure- Hydro turbine range [accessed 24/04/14] 11. Lancaster University Renewable Energy Group (LUREG). Hydro Resource Evaluation Tool: engineering options. [Internet]. [Cited 2014 April 18]. Available from: