Abstract: Fluid propulsive device for accelerating flow of fluid passing through the device, for pumping fluid, or solids carried in fluid, or for propelling the device through fluid. The device has a main body having a duct provided with primary and secondary jet means adapted to receive working fluid under pressure. The jet means extend peripherally around the duct generally within planes normal to duct central axis and direct conical sprays of working fluid downstream into the duct. Primary jet means sprays working fluid initially at a conical semi-angle of between 18.degree. and 30.degree. so as to converge inwards initially towards a theoretical apex of the cone of the spray adjacent the duct central axis. Secondary jet means disposed downstream of the primary jet means within plane containing theoretical apex sprays fluid initially at angle of between 6.degree. and 10.degree. to duct side wall.