Test results

Calibration

Weight of Block: 185,3 g (incl. ziptie)

Moment at 180mm distance: 0.327 Nm

Thrust:

Frequency (Hz)

0.4

0.8

Pitch Angle Flaps (°)

Measured Peak Force (N)

1,1

2,4

1,8

*servo did not achieve full range of motion

Turning:

Frequency (Hz)

0.8

Pitch Angle Flaps (°)

Pitch Factor 2nd Flap

0.5

-0.5

-1

Measured Peak Moment (Nm)

0,1

0,07

0,06

0,07

Results CFD:

Points:

Always detchaed flow → Force is generated by Actio/Reactio (just with Hydrodynamics 500% smaller factor 5)

Karman street just with low AoA

Cambered foil is in optimum and in comparable AoA better then stiff foil (10-15%)

Optimum of AoA is like in research not like in tests (45 instead of 35 stiff foil)

Interpretation.:

Why is tested optimum 35° and sim 45°?

heaving rod and teststand tilt a bit and thus change effective AoA

Why is F in sim higher than test?

we anticipate optimal pitch which isn’t always the pitch while the heave motion

we use averaged flow velocity but in real life its a sin function

losses because of movement in hardware

water is moving randomly after a time and not in simulation

Why is Cmabered worse in tests and better in sim compared to stiff

Engery loss in Momentum → cambering was not always equal in test (on both sides)

Camering in test not stable enough and to much movement in the parts → energy loss. Can’t ressist angainst water Force

teststand has also movement and can influence results

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