Wells-Turbine

The Wells turbine is a special air turbine, which is used in wave power plants with oscillating water column.

It works without valve flaps with constant direction of rotation, regardless of the direction of flow of moving through the water column in a chamber air. Their blades have a symmetrical wing profile, the median plane lies in the plane of rotation and perpendicular to the flow direction.

Their efficiency is lower than that of a turbine with a constant direction of flow and asymmetrical blade profiles. First, symmetric profiles have a higher drag coefficient than asymmetric even at optimum flow conditions. Second, the symmetric profile is particularly sensitive to high angle of attack ( ie low tip speed ratio ), as they occur in strongly fluctuating flow velocity in the velocity maxima. Then it comes to stall and dynamic lift collapses. This effect is responsible for ensuring that the efficiency of the Wells turbine is only between 0.4 and 0.7 under oscillating flow.

Another disadvantage is the lack of self-starting ability. To start the generator must be used as a motor.

This turbine design was developed in the late 1980s by Alan Wells in Belfast.

• Turbine
• Hydropower
• Marine energy