SU1172090A1 - Device for measuring sound level in aqueous medium of pipeline - Google Patents

Abstract

A DEVICE FOR MEASURING THE LEVEL OF SOUND PRESSURE IN AQUATIC MEDIUM OF A PIPELINE contains a K located on the measuring section of the pipeline with an installed hydrophone that communicates with the pipeline through an opening in its wall, which is designed to increase accuracy and noise immunity and extend the dimensions of the measurements of its dimensions, in order to increase the accuracy and noise immunity and expand the range of measurements of its dimensions. the low pressure side, the hole in the pipe wall is provided with a partition with N channels, the total area of which 2 cross sections is connected with the dimensions of the chamber and the cross section pipeline ratio (/ coek., -cosk j and V62 cos V .f (where A is the allowable correction for the measured sound pressure level; kf is the wave number; where CO is the circular frequency; (L C is the velocity of ultrasound propagation in the environment) wall thickness & camera height, fS, 7 "id where D-) is the cross-sectional area Hiw camera; P-fef where PQ is the cross-sectional area of the pipeline.

Description

The invention relates to the measurement of sound pressure in a moving aqueous medium in pipelines and can be used to measure sound pressure in various systems, 5 for example in ship cooling systems to prevent exceeding sanitary noise standards in rooms with people.

The purpose of the invention is to increase the accuracy and noise immunity and expand the measuring range towards low pressures.

The drawing shows the proposed device, section. fifteen

A device for measuring the sound pressure level contains a hydrophone 1 located in the chamber 2, which communicates with the measuring section of the pipeline 3 through a partition 4 20 with N channels 5. The number of channels is selected from the condition N = S ₂ / S _{ , where S _{2 is the} total cross-sectional area N channels, S ₄ - the area of one of the channels, and the number of channels should be more than one. '

The value of the cross-sectional area of the pipeline S _Q practically does not affect the calculation results. In the case of using a chamber communicating with the pipeline through one hole, the minimum sound pressure level is limited from below by the level of pressure pulsations arising on this hole. In this case, the sound pressure level can be recorded only when the indicated levels exceed the pressure pulsations in the measuring section. To reduce the formation of pressure pulsations at the hole, it must be made with a diameter of not more than 2 mm at flow rates V <8 m / s. I

When replacing one opening with shto- _h 'schadyu 5j channels, each of which has an area 5 at a flow rate of not more than 8 m / s, it is reached not distorted pulsatsyyami pressure fluid flow in the pipeline at the value of S', associated with the size measuring ⁵⁰ chamber and the cross-section of the pipeline by the ratio “Г j

where ω is the circular frequency; '

C is the velocity of propagation of ultrasound in the medium;

- thickness of the partition; ’

- camera height; ’

where 5 ^ is the cross-sectional area of the chamber,

where 5 ₀ is the cross-sectional area of the pipeline.

The principle of operation of the measuring device is as follows.

Since the camera communicates with the measuring section of the pipeline by channels with a total area, the hydrophone placed in it measures the pressure in the pipeline with an accuracy of at least 1-2 dB. At the same time, due to the fact that the area of each channel has a value of no more than 3.14 mm ² (diameter 2 mm), at which flow rates at the entrance to the measuring device, which is practically undistorted by pulsations, are achieved at flow velocities below 8 m / s, the range of measured sound pressure levels in the pipeline water stream. Thus, by reducing the level of pressure pulsations, the restriction from below on the value of the sound pressure level, which can be measured by placing the hydrophone in a chamber removed from the stream, communicating through one hole of arbitrary shape with the aquatic environment of the pipe, has been removed. wires. The range of measurement of sound pressure is expanded at the same time by 10-15 dB.

Claims (1)

DEVICE FOR MEASURING THE SOUND PRESSURE LEVEL IN A WATER PIPELINE ENVIRONMENT, containing a chamber located on the measuring section of the pipeline with a hydrophone installed inside it, communicating with the pipeline through an opening in its wall, characterized in that, in order to increase accuracy and noise immunity and extend the measurement range to the side low pressure, the hole in the wall of the pipeline is equipped with a partition with N channels, the total area & 2 of the cross section of which is associated with the size of the chamber and the cross section pipeline ratio where D is the allowable correction for the measured sound pressure level J wave number; where where where is the circular frequency; the speed of propagation of ultrasound in the medium f the thickness of the partition; chamber height, cross-sectional area of the chamber; ' cross-sectional area of the pipeline. where D is the allowable correction for the measured sound pressure level not higher than 1-2 dB, _ν ω, K is the wave number;