Vane-less cooling fan and engine system

The invention discloses a vane-less cooling fan and an engine system. The vane-less cooling fan comprises an air outlet pipeline which is of an annular structure; an annular barrier wall is arranged in the air outlet pipeline; the annular barrier wall and the outer wall of the air outlet channel form a first annular cavity; the annular barrier wall and the inner wall of the air outlet channel forma second annular cavity; a first annular flow channel is formed in the first annular cavity; a second annular flow channel is formed in the second annular cavity; the radial cross-sectional area of the first annular flow channel is greater than that of the second annular flow channel; and air is exhausted after flowing through the first annular flow channel and the second annular cavity in sequence. When the air flows into the second annular flow channel from the first annular flow channel, the flow speed of the air is accelerated and the flow speed of the air at an air outlet of a cooling fan is increased because of