Using OWC to Estimate Wave Height

Picture
 }Materials Used:
    Original Rig
    Ruler
    Anemometer

 


    The video on the right shows our results when an anemometer was used to get data to be used for calculation by velocities.  Wave height, wave period and areas were also measured for the calculation.

Calculations

Using OWC to Estimate Wave Height

}  Wave Pressure: P(z)=-ρgz + ρgKpη

}  Assume Shallow Water => Kp = 1

}  Assume: Max U occurs at τ/2

}  Therefore: ΔP = ρgH, ΔV=H * A0, Δt=τ/2

}  Q=H*A0/(τ/2)

}  Q= A1*U

}  H= A1*U*(τ/2)/A0

Results

}  Measured:

             A0= 45.6 cm. sq.

             A1=1.27 cm. sq.

     τ = 2 sec.

             U= 20 cm/s

             H=2.54 cm

}  Calculated:

            H= A1*U*(τ/2)/A0

      H=0.55 cm



Discussion

}  Possible Sources of Error        
    -Shallow Water Assumption: formulas used would have changed

    -Strainer Blocking Flow: not a big of pressure difference created as what could have been 

    -Oscillating Air Flow Interference

    -Wave Reflection Interference: Readings desturbed because of the waves refraction on the bathtub walls

    -Measurement Error: human error

    -Uneven wave generation

Conclusion

Oscillating Water Column is an excellent method for converting wave energy to usable power.  Unfortunatly it is not being used yet as a common source of energy. 

 

Using OWC to indirectly measure wave height should only be considered if interfering variables can be kept to a minimum.

University of Wisconsin Madison
CEE 514: Final Project
By: Nicole Johnson & Eric Olson
Copyright 2010