LMH Laboratory for Hydraulic Machines

Supervisor:

Dr. Mohamed Farhat (LMH)

Doctoral Assistants:

Amirreza ZobeiriVlad Hasmatuchi

Experimental Investigation of a Symmetric NACA 0009 Hydrofoil in Reversed Flow Configuration

Andrey M. Zakurdaev

Case Study and Experimental SetupMotivation and ObjectivesBoth rotating (runner-impeller) and stationary (guide vane and stay vane)blades in pump-turbine hydraulic machines are regularly subjected toreverse flow (pump mode) conditions. Understanding the flow in thisconfiguration and quantifying its hydrodynamic characteristics isparticularly important for mastering and subsequently controlling rotatingstall, a known issue frequently observed in annular blade arrays duringreverse mode operation at partial load.

Acknowledgements:

• Government of Canada• Natural Sciences and

Engineering Research Council (NSERC) of Canada

• HYDRODYNA partners

The present work took on the task of conducting an experimental investigation inorder to characterize the overall performance of a single hydraulic lift surface inpump mode and detail the flow behaviour under these conditions. This is a first-time study intended to regulate and improve subsequent numerical simulations ofthe flow inside pump-turbine machines during reverse modeoperation, as well as bring insight on how to design blade profilesused in stationary guide and/or stay vanes so as to ensure theiroptimal performance in both flow directions.

Case study:

Hydrofoil• bi-dimensional, symmetric• geometry: NACA 0009• rounded trailing edge• chord: 100 mm, maximum thickness: 10 mm

Natural and tripped flow transition conditions• leading edge surface roughness (5 mm

wide, ~100 µm high)Experimental setup:

LMH-EPFL high-speed cavitation tunnel

- max. velocity: 50 m/s- max. pressure: 16 bar- low turbulence- controlled via: Cref and σ- 150 x 150 x 750 mm test section:

Measurement Techniques Hydrodynamic balance: (lift and drag)

• hydrofoil mounted on a 5-bridge electronic balance Laser Doppler vibrometer: (vortex-induced vibration)

• non-intrusive device: Polytec PDV100 Static pressure sensors: (local pressure distribution)

• hydrofoil instrumented with 12 surface-embedded pressure sensors

Laser Doppler Velocimetry, LDV: (velocity profiles)• control volume set using two polarized light beams

High-speed image acquisition: (qualitative visualization)• camera: Photron Fastcam SA1• two flow visualization techniques:

1) microbubble generation 2) surface tufts

Results – Hydrodynamic PerformanceLift:

Drag: Pump modeTurbine mode

Natural BLTripped BL

α = 0°

α = 2°

α = 4°

α = 10°

Results – Vibration Analysis

Results – Pressure Distribution Results – Boundary Layer Velocity Profiles Cref= 10 m/s, σ = 8

Cref= 10 m/s, σ = 8

Tuft visualization of separation bubble as α is increased

Cref= 12 m/sσ = 8α = 3.5°