Quasiturbine engine
The Quasiturbine (Qurbine) is a « Positive Displacement » turbine alternative.

Suitable as a double-circuits Rotary Motor or Expander for compressed air, steam and other fluids, or (later) as an advanced Internal Combustion Rotary Engine, as well as (later) for Compressor of various thermodynamic cycles. The Quasiturbine is a compact, low weight and high torque machine with top efficiency, especially in power modulation applications.

The Quasiturbine is a pistonless Rotary Machine using a deformable rotor whose blades (sides) are hinged at the vertices. The volume enclosed between the blades of the rotor and the stator casing provides compression and expansion in a fashion similar to the familiar Wankel engine, but the hinging at the edges allows higher compression ratio and different time dependencies, while suppressing the Wankel rotor dead time, and this without the complex rotor synchronization gears.

Unlike vane pumps, which vane extension is important and against which the pressure acts to generate the rotation, the Quasiturbine contour seals have an imperceptible extension and the rotation does not result from pressure against these seals. Since the cylindrical (or oval) stator of vane devices has a radius of curvature greater than the rotor, the two surfaces (rotor - stator) cannot reach a close fit at top dead center (TDC), while the surfaces of both the rotor and stator of the Quasiturbine fit exactly against one another to produce a high compression ratio. This is why QT is efficient (less pressure charging losses), and this is why there is no vane combustion engine. Quasiturbine publishes « efficiency data ».

More at http://www.quasiturbine.com