1. NORWEGIAN HYDROPOWER CENTRE SEDIMENT EROSION IN HYDRAULIC TURBINES Biraj Singh Thapa, PhD Candidate (August 2013) Department of Energy and Process Engineering Supervisors: Prof. Ole Gunnar Dahlhaug Prof. Torbjørn Kristian Nielsen Prof. Bhola Thapa (KU)

2. Beauty Comes With Hidden Price! A view of November evening in Nepal 48 MW*3 Francis runner at Kaligandaki Power plant, Nepal 250 MW*6 Francis runner at Nathpa Jhakri Power plant, India Sediment erosion damage in guide vanes and facing plates Hydro power Opportunities 23 MW*2 Francis runner at Chawa Power plant, Chile

3. Research Problem Sediment erosion damage in guide vanes and facing plates

4. Research Methods Completed Turbine design Optimization Development of Test setup Reference Case Design of flow cascade Velocity Measurements Completed Pressure Measurements Optimization Parameters Progressing Analysis and Interpretation Next step Numerical Study Alternative Designs of GV Lab test of Alternative Designs

5. Inlet of Cascade Outlet of Cascade Section to optimize velocity components at inlet of runner Section to optimize velocity components at SV outlet Section fixed by free vortex flow CuSVo C1 U1 Cu1 Cm1 W1 CmSVo SV GV Runner Blade ω CSVo Design of Flow Cascade

6. Test Setup

7. Measurement Sections

8. Waterpower Laboratory NTNU

9. Pressure Side Suction Side Pressure along GV surfaceContour plot of velocity (PIV) Measurement Along GV Mid Span

10. Flow Along Clearance Gap Observation of vortex filament PIV Measurement

11. Erosion in runner hub Erosion in GV trailing Edge Correlating with Observations Photo Source: Ole G. Dahlhaug NACA 0012 Profile used for guide vanes High Pressure difference towards trailing edge More erosion in trailing edge walls due to high velocities and secondary flows Formation of clearance gap, inducing strong crossflow Increases relative velocity and reduces radial velocity at runner inlet towards hub and shroud Thus higher erosion in runner hub and shroud at inlet and lowered runner efficiency Other factors as RSI, Blade leaning design and operational parameters are equally important

12. NORWEGIAN HYDROPOWER CENTRE Thank You!!! biraj.s.thapa@ntnu.no