Abstract: Disclosed is an air conditioner that suppresses generation of leakage vortices between a fan and a shroud. An air conditioner according to an embodiment of the present invention includes: an axial fan for blowing air; a shroud partially surrounding a circumference of the axial fan to guide air blown by the axial fan; and a fence ring provided in an inner surface of the shroud and protruding in a radial direction from the inner surface of the shroud. In addition, the fence ring is disposed between a downstream end of the axial fan and a downstream end of the shroud.

Abstract: Disclosed is an air conditioner that suppresses generation of leakage vortices between a fan and a shroud. An air conditioner according to an embodiment of the present invention includes: an axial fan for blowing air; a shroud partially surrounding a circumference of the axial fan to guide air blown by the axial fan; and a fence ring provided in an inner surface of the shroud and protruding in a radial direction from the inner surface of the shroud. In addition, the fence ring is disposed between a downstream end of the axial fan and a downstream end of the shroud.

Abstract: Provided is a wake disturbing apparatus and method for reducing drag, which can considerably reduce drag caused by a sharp decrease in the pressure behind an object with a blunt trailing edge, such as a vehicle, while the object is traveling at high speed. The wake disturbing apparatus includes a plurality of disrupters, which are arranged at regular intervals along the trailing edge of the object to protrude to a predetermined height so that the vortical strength of the wake occurring around the rear part of the object can be reduced and the pressure at the base surface, which has been decreased due to the wake, can be recovered. Accordingly, it is possible to considerably reduce drag on a vehicle by simply attaching a wake disturbing apparatus to the vehicle without modifying the structure of the vehicle or using additional energy. Thus, it is possible to reduce power consumption of the vehicle and thus maximize the energy consumption efficiency.

Abstract: A micro channel unit having a shape designed to reduce a pressure drop when fluid passes through a connecting channel portion is provided. The micro channel unit includes a micro channel with a width of micrometer dimensions through which liquid flows. The micro channel includes a plurality of straight channel portions and connecting channel portions that connect each pair of adjacent straight channel portions. The connecting channel portions are wider than the straight channel portions connected by the connecting channel portions. The use of the micro channel unit can reduce the pressure drop when fluid passes through the connecting channel portions, thereby reducing the amount of power required to drive the fluid flow and further enabling miniaturization of microfluidic devices such as pumps and peripheral devices.

Abstract: Provided is a wake disturbing apparatus and method for reducing drag, which can considerably reduce drag caused by a sharp decrease in the pressure behind an object with a blunt trailing edge, such as a vehicle, while the object is traveling at high speed. The wake disturbing apparatus includes a plurality of disrupters, which are arranged at regular intervals along the trailing edge of the object to protrude to a predetermined height so that the vortical strength of the wake occurring around the rear part of the object can be reduced and the pressure at the base surface, which has been decreased due to the wake, can be recovered. Accordingly, it is possible to considerably reduce drag on a vehicle by simply attaching a wake disturbing apparatus to the vehicle without modifying the structure of the vehicle or using additional energy. Thus, it is possible to reduce power consumption of the vehicle and thus maximize the energy consumption efficiency.

Abstract: A micro channel unit having a shape designed to reduce a pressure drop when fluid passes through a connecting channel portion is provided. The micro channel unit includes a micro channel with a width of micrometer dimensions through which liquid flows. The micro channel includes a plurality of straight channel portions and connecting channel portions that connect each pair of adjacent straight channel portions. The connecting channel portions are wider than the straight channel portions connected by the connecting channel portions. The use of the micro channel unit can reduce the pressure drop when fluid passes through the connecting channel portions, thereby reducing the amount of power required to drive the fluid flow and further enabling miniaturization of microfluidic devices such as pumps and peripheral devices.