Guiding grid

A guiding grid in contact with an inlet of a fan, wherein the guiding grid comprises:

• a plurality of circumferential elements disposed concentrically relative to a central axis, spaced apart from each other in a radial direction, and forming different heights relative to a bottom surface in a side direction perpendicular to the central axis, wherein the plurality of circumferential elements are reduced in height relative to the bottom surface along the radial direction, and a closest one of the circumferential elements adjacent to the central axis forms a top height relative to the bottom surface;
• and
• a plurality of radial elements connected between each of two adjacent circumferential elements, wherein at least one of the radial elements is misaligned and discontinuous in the radial direction, wherein each of the plurality of circumferential elements has an inclination angle relative to the central axis, and the inclination angles of the plurality of circumferential elements are increased along the radial direction outwardly, wherein the inclination angles are greater than or equal to 0° and less than 90°.

A guiding grid in contact with an inlet of a fan, wherein the guiding grid comprises:

• a plurality of circumferential elements disposed concentrically relative to a central axis, spaced apart from each other in a radial direction, and forming different heights relative to a bottom surface in a side direction perpendicular to the central axis, wherein one of the circumferential elements forms a top height relative to the bottom surface, so that the circumferential elements are divided into an outer-ring region and a central region in the radial direction, wherein the plurality of circumferential elements located in the central region are increased in height relative to the bottom surface along the radial direction, and the plurality of circumferential element located in the outer ring region are reduced in height relative to the bottom surface along the radial direction;
• and
• a plurality of radial elements connected between each of two adjacent circumferential elements, wherein the plurality of radial elements are disconnected with the central axis in the radial direction, and each of the plurality of circumferential elements has an inclination angle relative to the central axis, and the inclination angles of the plurality of circumferential elements are increased along the radial direction outwardly, wherein the inclination angles are ranged from 0° to 90°.