A more recent multi-rotor design by Takahashi in 1976
shows a round stator with eccentrically located round
rotor and multi-vane (6) design [15]. Figure 4 illustrates
this design. The vanes are offset from the radial
direction. The design consists of axial located multistage
rotors for compression sections and expansion
sections. Constant volume/heat addition occurs
between the second stage compression and first stage
expansion and between the first and second expansion
stages. In 1980, Ramer shows a two rotor, multi vane
(four vane per rotor) design with a generally round stator
and concentrically located rotor [16]. Approximately
35% of the stator consists of an expanded volume that
contains the working fluid. One rotor assembly is for the
intake and compression stages and the second is for
expansion and exhaust stages