Fluid machine

A fluid machine comprising:

• a shaft portion extending in an axis direction;
• a shroud provided so as to surround the shaft portion and including a shroud inside surface that forms a flow path-forming surface defining an annular flow path through which fluid is flowable in the axis direction, the flow path being defined between the flow path-forming surface and the shaft portion;
• a first propeller rotatably provided around the axis in the flow path;
• a second propeller rotatably provided around the axis on a downstream side of the first propeller in the flow path;
• and
• a motor including
• a rotor that has a ring shape fixed to an outer circumferential portion of the second propeller and that is accommodated in the shroud, and
• a stator that has a ring shape surrounding the rotor via a clearance and that is fixed in the shroud,
• wherein the shroud includes
• an inlet flow path that is open at a portion between the first propeller and the second propeller in the flow path-forming surface and that brings the flow path and the clearance into communication with each other, and
• an outlet flow path that is open at a portion on a downstream side of and separated from the second propeller in the flow path-forming surface and that brings the flow path and the clearance into communication with each other, and
• wherein at least a portion of the flow path-forming surface on the downstream side of the second propeller decreases in diameter toward the downstream side such that a cross-sectional area of the flow path on the downstream side of the second propeller decreases toward the downstream side, whereby a static pressure in the outlet flow path is less than a static pressure in the inlet flow path.