Propulsion device for exerting thrust to a fluid

A propulsion device for exerting thrust to a fluid, which comprises a central hub having a front end and a rear end and being rotational about a rotational axis extending longitudinally between the front and rear ends, and at least two propulsive arrangements which protrude radially from the hub and which are evenly distributed about the circumference of the hub, wherein each propulsive arrangement comprises;

• a front propulsive member which:
• (i) extends radially from the hub, and (ii) defines an elongate front distance member and a front propulsive element, the front propulsive element extending radially from a front inner end to a front outer end,
• a rear propulsive member which:
• (i) extends radially from the hub, and (ii) defines an elongate rear distance member and a rear propulsive element, the rear propulsive element extending radially from a rear inner end to a rear outer end,
• an outer guide element which extends from the front outer end to the rear outer end at a radial outer guide element distance from the rotational axis,
• an inner guide element which extends from the front inner end to the rear inner end at a radial inner guide element distance from the rotational axis,
• and
• at least one intermediate propulsive element arranged between the front and rear propulsive elements and extending radially, from the inner guide element, to the outer guide element, wherein:
• the elongate front distance member and the elongate rear distance member each extend radially from the hub to the inner quide element,
• the longitudinal projections of the front propulsive element, the intermediate propulsive element and the rear propulsive element at least partially overlaps, and
• the inner guide element, the front distance member, the rear distance member and the periphery of the hub define an open space allowing free passage of the fluid.