JPH08201215A - Flow-staraightening duct - Google Patents

Abstract

PURPOSE: To greatly miniaturize an apparatus itself, reduce the setting area therefor and obtain a sufficient flow-straightening effect, by dividing the interior of an expanded duct by a plurality of partition plates, and setting the spreading angle of each divided duct to be not larger than an angle generating the detachment of the flow. CONSTITUTION: The spreading angle of a duct necessary for preventing the detachment of a flow from a wall surface of the duct and obtaining a flow straightening effect is set to be not larger than 7 deg.. When the duct is divided half by a partition plate 6, 14 deg. in total becomes allowable because each duct has a spreading angle of 7 deg.. The total length of an enlarged duct 3 can be reduced to 1/2. Similarly, if the duct is divided into three parts, the spreading angle becomes 21 deg. and the total length is approximately 1/3. If the duct is divided into four parts, the spreading angle is 28 deg. and the total length is reduced to about 1/4. In this manner, since the detachment of a flow is completely prevented, the total length of the enlarged duct 3 can be decreased remarkably. Moreover, an increase of a pressure loss results only from a frictional loss by the partition plates 6, i.e., the loss is considerably small, not causing a problem.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifying duct which prevents the flow of an enlarged duct portion used in a rectifying portion of a wind tunnel device from being separated from a wall surface of the duct and which has a required duct length shortened.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional wind tunnel device is provided with a rectifying portion 4 in order to obtain a uniform parallel flow in a measuring chamber. In the conventional method, the duct is gradually expanded on the downstream side of the blower 1 to recover the pressure, then swirled through the rectifying grid 4 and the like to remove the unbalanced flow, and then the nozzle 5 is provided to close the wall surface. The device is designed to accelerate and obtain a uniform flow. In addition, 2 is a fan casing, 3 is an expansion duct.

[0003]

However, in this case, the divergence angle of the enlarged duct portion must be about 7 ° or less in order to prevent separation of the flow from the wall surface. This angle is not a big problem in the case of a small wind tunnel, that is, a blower with a small capacity (diameter), but if a large wind tunnel, that is, a blower with a large capacity and a large diameter is required, it is necessary to provide a large expansion duct section. However, there is a drawback that the installation area of the device becomes large.

Therefore, if it is attempted to reduce the length of the enlarged duct by the conventional method, the divergence angle must be increased,
This method has the drawback that flow separation occurs from the wall surface of the duct and backflow occurs, so that no rectifying effect can be expected.

An object of the present invention is to provide a rectifying duct which can achieve a significant reduction in the size of the device itself and its installation area and can obtain the same rectifying effect as in the conventional case.

[0006]

The rectifying duct of the present invention comprises:
In an expanded duct portion such as a wind tunnel device, the inside of the expanded duct is divided by a plurality of partition plates 6, and the spread angle of each of the divided ducts is set to be equal to or smaller than an angle at which flow separation occurs.

[0007]

The functioning duct of the present invention is constructed as described above,
The divergence angle of the duct required to prevent separation of the flow from the wall surface of the duct and obtain the rectifying effect was set to 7 ° or less. Therefore, if the partition plate 6 divides the duct into two, the divergence angle of each duct is 7 °, and up to 14 ° is allowed in total.
The total length of the expansion duct can be halved.

Similarly, if it is divided into three parts, the divergence angle is 21 ° and the total length is about ⅓. If it is divided into four parts, the divergence angle is 28 ° and the total length is about ¼. In this way, the separation of the flow can be completely prevented, so that the total length of the expansion duct can be greatly reduced. Moreover, since the increase in the pressure loss is only the friction loss due to the partition plate 6, the loss is extremely small and there is no problem.

[0009]

Embodiments of the present invention will be described below with reference to FIG. FIG. 1 is a vertical cross-sectional view of the first embodiment in which the expanded duct 3 is divided into three # -digits by a partition plate 6, and the expanded angle of each duct is 7 ° or less. In addition, 1 is a blower, 4 is a rectifying grid, 5 is a nozzle, and 6 is a partition plate.
Therefore, flow separation can be prevented, and the total length of the expansion duct can be reduced to about 1/3 as compared with the conventional wind tunnel device shown in FIG.

[0010]

Since the rectifying duct of the present invention is constructed as described above, the apparatus itself and the installation area can be greatly reduced in size, and the same rectifying effect as that of the conventional apparatus can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a rectifying duct according to a first embodiment of the present invention.

FIG. 2 is a corresponding diagram of FIG. 1 of a conventional example.

[Explanation of symbols]

1 ... Blower, 2 ... Blower casing, 3 ... Expansion duct, 4
... rectifying grid, 5 ... nozzle, 6 ... partition plate.

Claims (1)

[Claims] 1. In an enlarged duct part such as a wind tunnel device,
A rectifying duct characterized in that the inside of the expanded duct is divided by a plurality of partition plates (6), and the divergence angle of each of the divided ducts is made equal to or less than the angle at which flow separation occurs.