JP2013019551A - Air conditioning duct - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning duct having a reduced pressure loss.SOLUTION: The air conditioning duct 10 includes a corner 15 at a direction changing part where the direction of flow of air delivered from an air conditioner changes. The corner 15 located on the flow inner peripheral side of the direction changing part is formed into a curved surface according to an elliptic arc where a short axis a is set along an upstream side duct 11 located upstream of the corner 15 and a long axis b is set along a downstream side duct 12 located downstream of the corner 15.

Description

  The present invention relates to an air conditioning duct that reduces pressure loss in a direction change portion of flowing air.

  Buildings such as buildings and transportation equipment such as railway vehicles are equipped with air conditioning equipment, but the air flowing through the air conditioning ducts is subject to pressure loss due to separation at the direction change parts where the flow changes such as branch parts. Yes. Therefore, the air-conditioning duct is designed with respect to the shape of the direction changing portion so that a predetermined wind speed can be obtained at the outlet. FIG. 6 is a view showing a direction changing portion of the air-conditioning duct branched into a T-shape. In the branch portion of the air conditioning duct 50, an air conditioner (not shown) is connected to the vertical duct 51, and the adjustment air flows through the horizontal ducts 52 and 53 branched in a T shape in different directions as indicated by arrows. And the corner | angular part 55 which changes from the vertical duct 51 to the horizontal ducts 52 and 53 is formed not by a right angle but by the curved surface of a circular arc, so that the flowing air does not become a separation flow.

Japanese Patent Application Laid-Open No. 07-133953 Japanese Patent Laid-Open No. 2005-207642

  In the conventional air conditioning duct, the curved surface of the corner portion 55 is formed by a circular arc. However, although this shape is more effective than the right angle in reducing the pressure loss, separation has occurred in the flowing air, and it has not been proved that the shape is sufficiently effective. Therefore, it has not been clear whether the conventional air-conditioning duct is sufficiently effective in reducing pressure loss.

  An object of this invention is to provide the air-conditioning duct which reduces pressure loss.

The air conditioning duct according to the present invention has a corner portion in a direction changing portion where the flow direction of the air sent from the air conditioner changes, and the corner portion located on the inner peripheral side of the flow of the direction changing portion is A curved surface formed along an elliptical arc that takes a minor axis along the upstream duct located upstream of the corner and takes a major axis along the downstream duct located downstream of the corner. It is characterized by being.
In the air conditioning duct according to the present invention, the ratio of the length of the long radius to the length of the short radius in the ellipse is preferably between 1.5 and 2.5.
In the air conditioning duct according to the present invention, it is preferable that the ratio of the length of the long radius to the length of the short radius in the ellipse is approximately 2.
Further, in the air conditioning duct according to the present invention, the length of the short radius of the ellipse is a value between 1/2 and 1/1 of the width dimension along the short axis direction of the downstream duct. preferable.
In the air conditioning duct according to the present invention, it is preferable that the length of the short radius of the ellipse is approximately ½ of the width dimension along the short axis direction of the downstream duct.

  According to the air conditioning duct of the present invention, the curved surface of the corner is an elliptical arc, and the ellipse has a minor axis in the direction along the upstream duct and a major axis in the direction along the downstream duct. By doing so, the pressure loss of the air flowing in the direction change portion where the corner portion of the present invention exists can be further reduced as compared with the corner air-conditioning duct formed by a conventional circular arc.

It is the figure which illustrated the simulation result of the air-conditioning duct of embodiment. It is the figure which illustrated the simulation result of the conventional air conditioning duct. It is the figure which showed the simulation result at the time of changing the radius a and b of the corner | angular part shown in FIG. 1 in the graph. It is the figure which showed the simulation result at the time of changing a short radius as a graph. It is the figure which accumulated and showed the shape of the corner | angular part of the length from which a short radius differs. It is the figure which showed the direction change part of the conventional air-conditioning duct branched in T shape.

  Next, the air conditioning duct according to the present invention will be described below with reference to the drawings. This embodiment is characterized by the corners of the air conditioning duct. For example, the air-conditioning duct 50 shown in FIG. 6 is the same as the air-conditioning duct 50, in which an air conditioner is connected to the vertical duct 51, and the adjusted air flows in the horizontal ducts 52 and 53 branched in a T-shape as indicated by arrows. explain. That is, also in this embodiment, the corner | angular part which comprises the same T-shaped direction change part as the air-conditioning duct shown in FIG. 6 is demonstrated.

  The air-conditioning duct of this embodiment is formed with curved surfaces at the corners as in the conventional case, but is formed with an elliptical arc instead of a perfect circle. Then, what kind of ellipse is optimal was examined by numerical simulation. FIG. 1 illustrates one of the simulation results. Here, since the T-shaped duct is bilaterally symmetric, only the air flow on one side (left side) is obtained, and the drawing shows a backflow region caused by separation. The air conditioning duct 10 is supplied with wind at a predetermined flow velocity (8.3 m / s) from the inflow portion 110 of the vertical duct 11, changes direction to the horizontal duct 12, and flows out from the outflow portion 120. At that time, the flow velocity at the wall surface of the air conditioning duct 10 was determined as 0 m / s, and the pressure at the outflow portion 120 was determined as 0 Pa.

  In the air conditioning duct 10, the corner 15 that changes from the vertical duct 11 to the horizontal duct 12 is an elliptical arc, takes a short axis along the vertical duct 11, and takes a long axis along the horizontal duct 12. At this time, the short radius a of the ellipse is about half of the width h of the horizontal duct 12, and the long radius b is set to be substantially the same value as the width h of the horizontal duct 12. That is, the ratio a: b between the short radius a and the long radius b is 1: 2. In such an air conditioning duct 10, when air is sent from the inflow portion 110, separation occurs in the horizontal duct 12 by the corner portion 15, and a backflow region 1 as shown in FIG. 1 is generated.

  On the other hand, FIG. 2 is a diagram showing simulation results for the conventional air conditioning duct 50. The dimensions of the vertical duct 51 and the horizontal duct 52 are the same as those of the air-conditioning duct 10, and the corner 55 formed with a curved surface by a circular arc has a radius c that is approximately half the width h of the horizontal duct 52. And when air flows on the same conditions as the air-conditioning duct 10, peeling by the corner | angular part 55 occurs in the horizontal duct 52, and the backflow area | region 5 as shown in FIG. 2 arises.

  The reverse flow regions 1 and 5 of the air conditioning ducts 10 and 50 are smaller in the reverse flow region 1 of the air conditioning duct 10 as can be seen by comparing FIGS. 1 and 2. That is, the pressure loss of the air conditioning duct 10 is smaller. Here, FIG. 3 is a graph showing a simulation result when the radii a and b of the corners shown in FIG. 1 are changed. Specifically, the pressure loss is shown when the ratio b / a of the length of the radius b along the horizontal duct 12 to the length of the radius a along the vertical duct 11 is varied. Therefore, the vertical axis represents the pressure loss coefficient, and the horizontal axis represents the radius ratio b / a. Moreover, it has shown about the case where the air which flows in from the inflow part 110 of the vertical duct 11 is changed with the flow velocity of 5 m / s, 8.3 m / s, and 10 m / s.

  The radius ratio b / a = 1 is a perfect circular arc shown in FIG. 2, and b / a = 2 is an elliptical arc shown in FIG. In addition, b / a = 0.5 with a long radius a on the vertical duct 11 side, or b / a = 1.5, 2.5, 3 with a long radius b on the horizontal duct 12 side as shown in FIG. Was determined for. Note that b / a = 0 is an inclined surface obtained by inclining the horizontal duct 12 from the vertical duct 11 diagonally in a straight line, and shows a case where the corner portion is eliminated.

  From the graph showing the simulation results, it was found that the elliptical arc has a smaller pressure loss coefficient than the circular arc (b / a = 1). Especially, b / a = 2 showed the smallest value. Even in the case of an elliptical arc, the pressure loss coefficient is smaller when the radius b on the downstream side duct 12 side is longer than when the radius a on the side of the vertical duct 11 is long. However, when b / a = 3 in which the radius b on the side duct 12 side is increased to three times the radius a on the side of the longitudinal duct 11, the pressure loss coefficient is larger than b / a = 0.5. I have. Therefore, it is preferable that the corner 15 of the air conditioning duct 10 has a ratio of radii a and b of approximately b / a = 1.5 to 2.5. Among them, the case where b / a = 2 was particularly optimal.

  Incidentally, the simulation result shown in FIG. 3 is obtained by setting the short radius a shown in FIG. 1 to about half of the width h of the lateral duct 12. Therefore, a numerical simulation was performed on the relationship between the minor radius a and the width h of the lateral duct 12 for b / a = 2, the best result shown in FIG. FIG. 4 is a graph showing the results. The vertical axis represents the pressure loss coefficient, and the horizontal axis represents the flow velocity. And it calculated | required about the case where the ratio a / h of the length of the short radius a with respect to the width h of the horizontal duct 12 was changed variously.

  The ratio of the length of the minor radius a to the width h of the lateral duct 12 is as follows: a / h = 1/8, 1/4, 3/8, 1/2, 5/8, 3/4, 7 / 8 and 1/1 were performed. As a result, as shown in FIG. 4, the value of the minor radius “a” was increased, and the value of the pressure loss coefficient was decreased as the width h of the lateral duct 12 was approached. Therefore, the corner 15 shown in FIG. 1 can reduce the pressure loss as the arc ellipse that specifies the curved surface shape becomes larger, and the length of the minor radius a is smaller than the width h of the lateral duct 12 a. When / h = 1/8, 1/4, and 3/8, a sufficient pressure loss coefficient could not be obtained.

  Therefore, the size of the minor radius a is preferably equal to or greater than h / 2, which is half the width h of the lateral duct 12. However, considering only the pressure loss, it is preferable to match the short radius a with the width h of the lateral duct 12, but as the short radius a increases, the space in the corner 15 increases. Therefore, the space required for the arrangement of devices and members located near the corner 15 on the outside of the air conditioning duct 10 is narrowed. For example, in a railway vehicle in which an air conditioner is installed on a roof, a vertical duct 11 and a horizontal duct 12 passing through the roof structure are connected from the air conditioner on the roof.

  The space on the roof of the car body is very narrow, and there may be a case where a predetermined device is installed or a bone member passes through it. If the space outside the air conditioning duct is narrowed, the space for arranging the device etc. The problem that will be taken away. Here, FIG. 5 shows corner portions when the ratio a / h of the length of the minor radius a to the width h of the lateral duct 12 is 1/2, 5/8, 3/4, 7/8, 1/1. FIG. As can be seen from this figure, the corners of a / h = 1/2 are deepest inside the duct, and in the order of a / h = 5/8, 3/4, 7/8, 1/1, It protrudes to the outside. Therefore, although the pressure loss can be reduced if the ellipse constituting the corner portion becomes large, the space outside the air conditioning duct is narrowed.

  From the simulation results of FIG. 4, the difference between the values of the pressure loss coefficients having a / h of 1/2 to 1/1 is small. Therefore, when considering both the pressure loss coefficient and the space outside the air conditioning duct, a / h = 1/2, in which the length of the minor radius a is half the width h of the duct 12, is appropriate. However, when the space outside the air conditioning duct is not restricted by the arrangement of the device or the like, the length of the minor radius a may be increased.

  Therefore, the air-conditioning duct 10 of this embodiment shown in FIG. 1 is configured such that the curved surface of the corner portion 15 is an elliptical arc, and the ellipse takes a short axis in the direction along the vertical duct 11 and The long axis is taken in the direction along the duct 12. The ratio of the short radius a to the long radius b has a width of about b / a = 1.5 to 2.5, but b / a = 2 is optimal. The short radius a is preferably about half or more of the width h of the horizontal duct 12, but h / 2 is appropriate in consideration of the space outside the air conditioning duct.

  Thus, in the corner portion 15 having a curved surface formed by an elliptical arc, the backflow region 1 shown in FIG. 1 can be made smaller than the backflow region 5 generated by the conventional corner portion 55 shown in FIG. Therefore, when the flow velocity is 8.3 m / s, the pressure loss coefficient is reduced to about 0.69 in the corner portion 15 of the present embodiment while it is about 0.71 in the conventional corner portion 55. Can do. And reducing the backflow region 1 also reduces noise in the air flowing through the air conditioning duct 10.

As mentioned above, although embodiment of the air-conditioning duct based on this invention was described, this invention is not limited to this, A various change is possible in the range which does not deviate from the meaning.
In the above embodiment, the corner portion 15 that changes from the vertical duct 11 connected to the air conditioner to the horizontal duct 12 has been described. However, if the corner portion where the flow path branches exists, the location of the air conditioning duct is specified. It is not a thing.
Although the said air-conditioning duct 10 demonstrated the corner | angular part of the T-shaped part, you may make it apply about the inner peripheral side corner | angular part of an L-shaped part.

1 Backflow area 10 Air-conditioning duct 11 Vertical duct 12 Horizontal duct 15 Corner

Claims (5)

In the air conditioning duct having a corner portion in the direction changing portion where the flow direction of the air sent from the air conditioner changes,
The corner portion located on the inner peripheral side of the flow of the direction changing portion has a short axis along the upstream duct located on the upstream side of the corner portion, and the downstream duct located on the downstream side of the corner portion. An air conditioning duct characterized by being a curved surface formed according to an elliptical arc having a major axis along the axis. In the air-conditioning duct according to claim 1,
An air conditioning duct characterized in that the ellipse has a ratio of the length of the major radius to the length of the minor radius between 1.5 and 2.5. In the air-conditioning duct according to claim 1,
The elliptical air-conditioning duct is characterized in that the ratio of the length of the major radius to the length of the minor radius is approximately 2. In the air-conditioning duct according to any one of claims 1 to 3,
The ellipse is characterized in that the length of the short radius is a value between 1/2 and 1/1 of the width dimension along the short axis direction of the downstream duct. In the air-conditioning duct according to claim 4,
The ellipse is characterized in that the length of the short radius is approximately ½ of the width dimension along the short axis direction of the downstream duct.

Images