An exemplary embodiment of the present disclosure provides an intake device including: an annular flow path which is formed in a circular housing; an inlet part which is installed at one side of the housing and guides an inflow of a fluid into the flow path; a outlet part which is installed at the other side of the housing and guides a discharge of the fluid which flows into the inlet part and passes through the flow path; a piston which is disposed in the flow path, and rotates along the flow path so as to compress the fluid introduced through the inlet part; and an opening and closing unit which is installed in the flow path between the inlet part and the outlet part, includes a plurality of opening and closing members, and elastic members which are installed between the plurality of opening and closing members and the flow path so as to support the plurality of opening and closing members, respectively, and opens and closes the flow path by pressing the piston, in which when the pressing of the piston is released, the plurality of opening and closing members closes the flow path by pressing force of the fluid which presses outer circumferential surfaces of the plurality of opening and closing members in a direction in which the flow path is closed, and by elastic force of the elastic member.

The disclosure provides rotary machines that include, in one embodiment, a rotatable shaft defining a central axis A, the shaft having a first end and a second end. The shaft can have a first hub disposed thereon with a plurality of cavities. At least one contour is slidably received into an arcuate cavity in an exterior surface of the hub. The contour has a convex outer surface that cooperates with an inwardly facing curved surface of a housing to form a working volume.