JPH0577794A - Noise reducing device for high-speed flow noise - Google Patents

Abstract

PURPOSE:To effectively reduce noise generated by a highspeed flow of a jet engine and so on with a simple device. CONSTITUTION:A damping plate 2 is provided at the rear edge of a member in contact with a high-speed fluid, for example, a jet duct 1, along the flow direction of the high-speed fluid, and generation of noise is restricted by relaxing speed fluctuation of the fluid by the damping plate 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noise reduction device for noise generated by a high speed flow such as a jet flow of a jet engine.

[0002]

2. Description of the Related Art Aircraft noise, which is a pollution problem, is generated by the aerodynamic noise generated by the jet flow of a jet engine.
It is one of the causes, and it is strongly desired to reduce it.

In order to meet such a demand, it is conceivable to use a suppressor nozzle shown in FIG. 3 and a type such as a collaged nozzle shown in FIG.

In the suppressor nozzle shown in FIG. 3, a jet flow F of a jet engine is provided with a plurality of nozzles 02 opening rearward at the trailing edge of a jet pipe 01 flowing therein, and jetted from the nozzle 02. The jet stream draws in outside air and reduces the noise generated by the jet engine jet stream.

In the collaged nozzle shown in FIG. 4,
The jet F of the jet engine is provided with a pleated opening 03 at the trailing edge of the jet pipe 01, and the arrow f
As shown in, the air is made to flow from the outside through the opening 03 to the trailing edge of the jet pipe 01 to reduce noise generated by the jet engine jet flow.

[0006]

In the noise reduction device of the type in which air is sucked or poured into the trailing edge of the jet pipe from the outside as shown in FIGS. 3 and 4, the air from the outside is mixed with the jet flow. As a result, the propulsion efficiency is lowered, which makes it difficult to put it into practical use.

The present invention has been made in view of the above,
An object of the present invention is to provide a noise reduction device for high-speed flow noise that can effectively reduce noise without impairing propulsion efficiency and the like as much as possible.

[0008]

In the noise reduction device for high-speed flow noise according to the present invention, a damping plate is provided at the trailing edge of a member in contact with the high-speed fluid along the flow of the high-speed fluid.

[0009]

In the trailing edge portion of a member such as a jet pipe or a duct that is in contact with a high-speed fluid, the velocity component along the flow direction of the fluid fluctuates remarkably with time, and the shearing force changes due to the velocity fluctuation to generate noise. .

According to the present invention, the violent velocity fluctuation of the flow of the high-speed fluid at the trailing edge of the member can be alleviated by the damping plate, so that the generation of noise is suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Reference numeral 1 is a cylindrical jet pipe through which a jet F of a jet engine flows.
A plurality of damping plates 2 are arranged around the trailing edge at regular intervals.

As shown in FIG. 2, the attenuating plate 2 has a water drop-like shape in which the front portion is slightly pointed, and the jet F of the jet engine is jetted to the jet pipe 1 along the axial center line. In the flow direction of the jet pipe 1, that is, in the axial direction of the jet pipe 1, and its rear end portion is arranged so as to project from the rear edge of the jet pipe 1.

In this embodiment, fluctuations in the velocity of the jet engine jet F at the trailing edge of the jet pipe 1 are alleviated by a plurality of damping plates 2 provided around the trailing edge of the jet pipe 1, thus suppressing noise generation. can do.

Further, the air from the outside is not poured into the jet pipe 1, and the propulsion efficiency is not lowered.

In this embodiment, the present invention is applied to a jet pipe, but the present invention is a member contacting a high speed fluid.
For example, it can be widely applied to a blade-shaped trailing edge portion, an orifice of a conduit, and the like.

[0016]

According to the present invention, with a simple structure, high-speed flow noise generated from the trailing edge of a member such as a jet pipe or a duct which comes into contact with a high-speed fluid can be effectively prevented without inflowing a fluid such as air from the outside. Can be reduced to

[Brief description of drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a trailing edge portion of a jet pipe of the same embodiment.

FIG. 3 is a perspective view of an example of a conventional noise reduction device for high-speed flow noise.

FIG. 4 is a perspective view of another example of a conventional noise reduction device for high-speed flow noise.

[Explanation of symbols]

 1 Jet pipe 2 Damping plate F Jet engine jet

Claims (1)

[Claims] 1. A noise reduction device for high-speed flow noise, characterized in that a damping plate along the flow of the high-speed fluid is provided at the trailing edge of a member that contacts the high-speed fluid.