CN105784096A - Measurement system and measurement method for jet noise of water filling pipe - Google Patents

Abstract

The invention discloses a measurement system and a measurement method for jet noise of a water-filled pipeline. Including water-filled pipes, reverberation box, plexiglass plate and vertical line array of hydrophones; the reverberation box is a steel cuboid structure filled with water, the top has no cover, and the bottom is supported by beams; the plexiglass plate is installed in the reverberation box Inside, the reverberation box is divided into two parts: the jet area and the test area; the water-filled pipe is placed in the jet area of the reverberation box; the vertical line array of hydrophones is placed in the test area inside the reverberation box. The invention reliably eliminates the pipe wall radiation noise produced by the water-filled pipeline being impacted by the water flow or the vibration of the water pump, etc., and eliminates the flow noise caused by the movement of the hydrophone when the space is averaged; the method for measuring the jet noise of the water-filled pipeline eliminates the When measuring jet noise in free field, the hydrophone is affected by "false sound" caused by the impact of water flow; the advantage of reverberation method is used to reduce the workload of free field measurement of radiated sound power of jet noise in water-filled pipelines.

Description

A measurement system and method for jet noise of a water-filled pipeline

technical field

The invention belongs to the field of acoustic measurement, in particular to a measurement system and method for jet noise of a water-filled pipeline.

Background technique

Underwater jet noise is generally caused by the water in the water-filled pipe submerged in the water being sprayed from the nozzle at a certain flow rate, and the radiation noise generated by the interaction between the fast-sprayed water flow and the still water due to the sharp mixing of the two. The magnitude of jet noise (non-cavitation) is generally small, and it is easy to be submerged by the radiation noise of pipe wall vibration. If the continuous moving hydrophone in the reverberation method is used for spatial averaging to collect jet noise, the The low-speed flow noise generated by continuous motion will be mixed in the jet noise, which is very unfavorable for the experimental research of underwater jet noise. Patent (CN104132727A)---a high-rise/super high-rise building drainage pipe noise testing system and testing method and patent (CN101368845A)---drainage pipe noise detection room and its detection method, both involve the drainage pipe in the air Radiation noise test; Wang Man (see Applied Acoustics, 2003(1): 35-38) carried out the study on the noise radiation control of liquid-filled pipelines, only placing hydrophone sound intensity arrays at the nozzles to evaluate the acoustic performance of the muffler , there is no measurement system and measurement method related to the jet noise generated by the rapid jetting of the water flow of the water-filled pipeline into the still water.

Contents of the invention

The purpose of the present invention is to provide a measurement system for jet noise of water-filled pipelines with simple structure and good measurement effect. The object of the present invention also includes providing an accurate and effective method for measuring the jet noise of the water-filled pipeline.

A measurement system for jet noise of a water-filled pipeline, including a water-filled pipeline, a reverberation box, a plexiglass plate and a vertical line array of hydrophones;

The reverberation box is a steel cuboid structure, filled with water, with no cover at the top and beam support at the bottom; the plexiglass plate is installed inside the reverberation box, which divides the reverberation box into two parts: the jet area and the test area; the water-filled pipeline Placed in the jet area of the reverberation box; the vertical line array of hydrophones is placed in the test area of the reverberation box.

A measurement system for jet noise of a water-filled pipeline may also include:

1. N pairs of damping boxes are installed on the pipe body of the water-filled pipeline. The damping box is a double-layer semi-cylindrical shell structure without a top cover. The inner diameter of the vibration-damping box is the same as the outer diameter of the water-filled pipeline, and the double-layer semi-cylindrical There are lugs at both ends of the shell structure, and there are through holes on the lugs. The lugs of each pair of damping boxes are opposite and connected at the lugs. The interior of the damping boxes is filled with iron sand.

2. A pair of nozzle clamps are installed at the nozzle of the water-filled pipeline. The nozzle clamp is a semi-circular structure. The inner diameter of the nozzle clamp is the same as the outer diameter of the water-filled pipeline. A through hole is provided, and the lugs of the two nozzle fixtures are opposite and connected at the lugs.

3. The nozzle of the water-filled pipeline is equipped with a baffle, and the baffle is connected with the nozzle fixture; the inner diameter of the baffle is the same as the outer diameter of the water-filled pipeline, and the lower surface of the baffle is flush with the nozzle of the water-filled pipeline. neat.

4. One end of the water-filled pipe is connected to the jet source, and the other end of the water-filled pipe is placed in the center of the jet area of the reverberation box. The axis of the water-filled pipe is perpendicular to the water surface in the reverberation box. The nozzle and baffle of the water-filled pipe The upper surface is submerged under water.

5. The outer diameter of the baffle is three times the outer diameter of the tube.

A method for measuring water-filled pipeline jet noise, comprising the following steps,

Step 1: Fill the reverberation tank with water, measure the background noise at the test point in the reverberation tank with a vertical line array of hydrophones, and sum and average the background noise at different measuring points;

Step 2: Hang the transmitting transducer in the center of the jet area in the reverberation box, measure the sound pressure power spectrum and reverberation time at the test point in the reverberation box through the vertical line array of the hydrophone, and analyze the different The sound pressure power spectrum and reverberation time at the measuring point are summed and averaged;

Step 3: After the water-filled pipeline is installed with a damping box, a nozzle fixture and a baffle, the nozzle of the water-filled pipeline is placed near the water surface, so that the water in the water-filled pipeline is sprayed into the jet area of the reverberation box at a speed K, The overflowing water is exported through the diversion device of the reverberation box;

Step 4: Measure the sound pressure power spectrum of the underwater jet noise formed by the water-filled pipeline at the position of the measuring point through the vertical line array of the hydrophone in the reverberation box;

Step 5: Use the sound pressure power spectrum data and reverberation time data of the transmitting transducer in the free field to calculate the room constant of the reverberation box, and correct the sound pressure power spectrum in step S4 to obtain the underwater jet flow of the water-filled pipeline The equivalent free field sound pressure level of the noise and the radiated sound power of the free field.

Beneficial effect:

The advantage of the present invention is that the box made of steel plate is used as the reverberation box to test the jet noise of the water-filled pipeline. Since the inside of the reverberation box is filled with water and the outside is air, the characteristic impedance of the box wall is larger than that of air Many (nearly 80,000 times), the sound waves radiated from the jet noise to the box wall can return to the reverberation box well, and the sound energy loss is very small (about 1/1000), by calibrating the room constant of the reverberation box, The equivalent free-field sound pressure level of the jet noise of the water-filled pipeline and the radiated sound power of the free-field can be obtained; the vibration-damping box is installed on the body of the water-filled pipeline to suppress vibration, reducing the sound energy radiated from the pipe wall to the water , to a large extent attenuate the influence of the radiation noise of the pipe wall; the jet noise test is carried out by placing the axis of the water-filled pipe perpendicular to the water surface in the reverberation box, and the nozzle is just immersed in the water surface in the reverberation box. Air, the lower part is water, which belongs to the absolute soft boundary in acoustics, and when the nozzle is immersed in the water surface, the radiation impedance of the nozzle is lower than that when the water-filled pipe is completely immersed in water, which also weakens the flow of the nozzle to the water. The ability to radiate sound waves, since the largest jet radiation noise is generated at a space position 8-10 times the nozzle diameter from the nozzle plane, so placing the nozzle on the water surface will not cause the loss of jet radiation noise; The upper surface of the baffle is just submerged under the water, which cuts off the path of the eddy current formed when the water in the water-filled pipe is quickly sprayed into the water, and avoids the influence of the eddy current noise on the jet noise test.

The jet noise measurement method of the water-filled pipeline of the present invention avoids the impact of the jet flow on the hydrophone when the jet noise is measured in the free field, which will cause "false sound" effects; the measurement method controls the jet flow in the jet flow area, and the The sound energy is transmitted to the test area through the plexiglass plate. Since the test area is still water, the influence of the hydrophone from the impact of the flow is well avoided; the measurement method is to use the hydrophone vertical line array fixed point to measure the jet radiation noise , the method of continuously moving the hydrophone for spatial averaging in the underwater reverberation method is not used, which avoids the influence of flow noise caused by the relatively static water movement of the hydrophone and the connecting cable of the hydrophone during the test, which also reduces the charging The background noise of the hydrophone itself during the test of the jet noise of the water pipeline; the workload of measuring the jet noise of the water-filled pipeline by using the reverberation box combined with the reverberation method is much smaller than that of the free field measurement of the jet noise, and the test implementation easier.

Description of drawings

Fig. 1 is a schematic diagram of a reverberation box;

Figure 2 is a schematic diagram of the placement of the water-filled pipeline;

Fig. 3 is a sectional view of the damping box;

Fig. 4 is a top view of the damping box;

Figure 5 is a top view of the nozzle fixture and the baffle;

Fig. 6 is a schematic diagram of a vertical line array of a hydrophone;

Figure 7 is a schematic diagram of the location of the measuring points in the reverberation box test area;

Fig. 8 is a flowchart of an embodiment of the water-filled pipeline jet noise measurement system and measurement method of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The object of the present invention is to provide a measurement system and method for jet noise of water-filled pipelines, which can solve the measurement problem of jet-flow noise of water-filled pipelines.

A measurement system and method for measuring jet noise of a water-filled pipeline, comprising a water-filled pipeline, a reverberation box, a plexiglass plate, and a vertical line array of hydrophones, the water-filled pipeline is installed in the jet flow area in the reverberation box, and the The reverberation box is a cuboid structure without a top cover, the bottom is supported by beams, the inside is filled with water, and the outside is air. The plexiglass plate divides the reverberation box into two parts: a jet area and a test area; the hydrophone The vertical line array is placed in the test area of the reverberation box to collect the noise radiated by the water-filled pipe jet.

The water-filled pipeline is a steel circular structure.

The volume of the jet area of the reverberation box is twice the volume of the test area, and there are multiple measuring point positions in the test area of the reverberation box.

The pipe body of the water-filled pipeline is equipped with a vibration-damping box. The vibration-damping box is a double-layer semi-cylindrical shell structure without a top cover, and the inside is filled with iron sand. The inner diameter of the vibration-damping box is the same as the outer diameter of the water-filled pipeline. There are lugs on the outside of the box, and there are four bolt through holes on the lugs. The difference between the outer and inner radii of the double-layer semi-cylindrical shell is ten times the thickness of the pipe wall; the nozzle of the water-filled pipeline is installed with a nozzle The fixture, the nozzle fixture is a semi-circular structure, with three bolt through holes, the inner diameter of the nozzle fixture is the same as the outer diameter of the water-filled pipe, the outer side of the nozzle fixture has lugs, and there are two a bolt through hole; a baffle is installed at the nozzle of the water-filled pipeline, the baffle is a ring structure, the diameter of the inner ring is the same as the outer diameter of the water-filled pipeline, and there are threaded holes on the baffle, the threaded holes The center of the baffle is aligned with the center of the bolt through hole on the fastened nozzle fixture, the thickness of the baffle is twice the thickness of the pipe wall, and the outer diameter of the baffle is three times the outer diameter of the nozzle.

Put the two damping boxes on the pipe body of the water-filled pipeline. The lugs of the two damping boxes are opposite to each other. Thread studs at the lugs and fasten them with nuts. The damping boxes are installed on the water-filled pipeline. On the pipe body of the pipeline, iron sand is filled inside the damping box, and five pairs of damping boxes are installed on the pipe body of the water-filled pipeline, and the interval between two pairs of damping boxes is the outer diameter length of the water-filled pipeline; The lugs are opposite to each other. Double-headed studs are passed through the lugs, and nuts are used to fasten them. The nozzle clamp is installed at the nozzle of the water-filled pipeline. The distance between the nozzle clamp and the nozzle plane is the baffle plate. the thickness of the baffle; put the baffle into the nozzle, align the screw holes on the baffle with the through holes on the nozzle fixture, screw the bolts through the through holes on the nozzle fixture into the baffle, and tighten the bolts so that the baffle The plate is flush with the nozzle, and sealant is applied to the gap between the baffle and the nozzle to block the gap, and the sealant is scraped off with a paper knife to make a good fit between the baffle and the nozzle.

One end of the water-filled pipeline is connected to the jet source, the other end of the water-filled pipeline is placed in the center of the jet area of the reverberation box, the axis of the water-filled pipeline is perpendicular to the water surface in the reverberation box, and the nozzle and baffle of the water-filled pipeline The upper surface has just been submerged under water.

The vertical line array of hydrophones is a line array of hydrophones, and the hydrophones are arranged at equal intervals. The hydrophones at both ends of the vertical line array of the hydrophones cannot approach the water surface and the bottom of the water tank, and the vertical line array of the hydrophones is placed In the test area of the reverberation box.

A water-filled pipeline jet noise measurement system and measurement method, the steps of the measurement method are as follows:

Step S1: Fill the reverberation tank with water, measure the background noise at the measuring points in the test area through the vertical linear array of the hydrophone at the designated position in the test area, and compare the background noise at different measuring points to sum and average;

Step S2: Hang the transmitting transducer at the center of the jet area of the reverberation box, and measure the sound pressure of the sound source at different spatial measuring points in the test area through the vertical line array of the hydrophone in the test area according to the position of the measuring point Power spectrum, reverberation time, and sum and average the sound pressure power spectrum and reverberation time of the sound source at different spatial measuring point positions;

Step S3: After installing the damping box, nozzle fixture and baffle on the water-filled pipeline, the nozzle of the water-filled pipeline and the upper surface of the baffle are just submerged in the water surface, and the jet source is turned on so that the water in the water-filled pipeline The speed is sprayed into the jet area of the reverberation box, and the overflowing water is exported through the diversion device of the reverberation box;

Step S4: Measure the sound pressure power spectrum of the underwater jet formed by the water-filled pipeline in the test area according to the position of the measuring point through the vertical line array of the hydrophone, and compare the sound pressure power spectrum at different spatial measuring point positions to sum and average;

Step S5: Use the sound pressure power spectrum data and reverberation time data of the transmitting transducer under free field conditions to obtain the room constant of the reverberation box, and correct the sound pressure power spectrum in step S4 to obtain the water-filled The equivalent free-field sound pressure level and the free-field radiated sound power of the pipe underwater jet.

The invention discloses a measurement system and method for measuring jet noise of a water-filled pipeline, which comprises a water-filled pipeline, a reverberation box, a plexiglass plate, and a vertical line array of hydrophones. area, the reverberation box is a steel cuboid structure, and the plexiglass plate divides the reverberation box into two parts: a jet flow area and a test area, and the vertical line array of hydrophones is placed in the test area of the reverberation box; The water-filled pipeline jet noise measurement system reliably eliminates the pipe wall radiation noise caused by the water-filled pipeline being impacted by the water flow or the vibration of the water pump, etc., and eliminates the flow noise caused by the movement of the hydrophone when the space is averaged; the water-filled pipeline The measurement method of the pipeline jet noise eliminates the influence of the "false sound" caused by the impact of the water flow on the hydrophone when the free field measures the jet noise, and uses the advantages of the reverberation method to reduce the radiated sound of the free field measurement of the jet noise of the water-filled pipeline power workload.

A measurement system and method for measuring jet noise of a water-filled pipeline, comprising a water-filled pipeline, a reverberation box, a plexiglass plate, and a vertical line array of hydrophones, the water-filled pipeline is placed in the jet flow area of the reverberation box, and the The reverberation box is a steel cuboid structure with no cover at the top and a beam support at the bottom without contacting the ground. The plexiglass plate divides the reverberation box into two parts: the jet area and the test area; the vertical line of the hydrophone The array is placed in the test area in the reverberation box; the axis of the water-filled pipe is perpendicular to the water surface in the reverberation box, and the upper surface of the nozzle and the baffle is just submerged under the water.

The pipe body of the water-filled pipeline is equipped with a vibration damping box. The vibration damping box is a double-layer semi-cylindrical shell structure with no cover at one end. There are lugs at both ends of the double-layer semi-cylindrical shell structure. Columns and nuts fix the damping box on the pipe body, and iron sand is filled inside the damping box.

A nozzle clamp is installed on the nozzle of the water-filled pipeline, and the nozzle clamp is a semi-circular structure with bolt through holes.

The nozzle of the water-filled pipeline is installed with a baffle, and there are screw holes on the baffle, and the center of the screw hole is aligned with the center of the bolt through hole in the fastened nozzle fixture, and the baffle is fastened by double-ended studs and nuts on the nozzle clamp. The outer surface of the baffle is flush with the mouth of the water-filled pipeline.

The inner diameter of the damping box is the same as the outer diameter of the water-filled pipeline, the inner diameter of the spout clamp is the same as the outer diameter of the water-filled pipeline, and the inner diameter of the baffle is the same as the outer diameter of the water-filled pipeline. The difference between the outer and inner diameters of the damping box is ten times the thickness of the pipe wall, the thickness of the baffle is twice the thickness of the pipe wall, and the outer diameter of the baffle is three times the outer diameter of the pipe.

The hydrophone vertical line array is composed of calibrated hydrophones with amplitude and phase, and the measurement method includes the following steps:

Step S1: Fill the reverberation box with water, measure the background noise at the measuring point of the test area in the reverberation box through a vertical line array of hydrophones, and sum and average the background noise at different measuring points ;

Step S2: Hang the transmitting transducer in the center of the jet area in the reverberation box, measure the sound pressure power spectrum and reverberation time at the test point in the reverberation box through the vertical line array of the hydrophone, and analyze the different The sound pressure power spectrum and reverberation time at the measuring point are summed and averaged;

Step S3: After the water-filled pipeline is installed with a vibration damping box, a nozzle fixture and a baffle, the nozzle of the water-filled pipeline is placed near the water surface, so that the water in the water-filled pipeline is sprayed into the jet area of the reverberation box at a certain speed , the overflow water is exported through the diversion device of the reverberation box;

Step S4: Measure the sound pressure power spectrum of the underwater jet noise formed by the water-filled pipeline at the position of the measuring point through the vertical line array of hydrophones in the reverberation box;

Step S5: Use the sound pressure power spectrum data and reverberation time data of the transmitting transducer in the free field to calculate the room constant of the reverberation box, and correct the sound pressure power spectrum in step S4 to obtain the underwater jet flow of the water-filled pipeline The equivalent free-field sound pressure level of the noise and the radiated sound power of the free field;

In steps S1, S2 and S4, also include:

The vertical line array of hydrophones moves in the test area according to the position of the test point during the test, and after moving to the designated position, the test measurement is performed, requiring the vertical line array of hydrophones in steps S2 and S4 The deployment position remains the same.

As shown in Figures 1 to 7, a measurement system and method for measuring jet noise of a water-filled pipeline includes a reverberation box 1, a plexiglass plate 2, a water-filled pipeline 3, and a vertical line array of hydrophones 4. The reverberation box 1 is made of steel plate and has a cuboid structure with no cover on the top. The plexiglass plate 2 is inserted into the reverberation box 1. Five pairs of damping boxes 31 are installed on the body of the water-filled pipeline 3 . A nozzle clamp 32 and a baffle 33 are installed on the nozzle of the water-filled pipeline 3 , and the vertical line array 4 of hydrophones is composed of eight hydrophones 41 .

The size of the reverberation box 1 is 9m in length, 3.6m in width, and 1.7m in height, and the thickness of the box body is 1cm. There is an overflow tank at the top of the reverberation box 1. , outside is air.

The size of the plexiglass plate 2 is 3.58m in length, 1.7m in width, and 2cm in thickness. The plexiglass plate 2 is inserted into the reverberation box 1, where the edge of the plexiglass plate 2 joins the reverberation box 1, Use glass glue for potting and caulking, and use a paper knife to scrape off the burrs of the glass glue. The plexiglass plate 2 divides the reverberation box 1 into a jet area and a test area. The volume of the jet area is about 30% of the volume of the test area. double.

The water-filled pipe 3 is a steel circular pipe filled with water, the inner diameter of the pipe is 88mm, the outer diameter of the pipe is 108mm, and the length is 2m. One end of the water-filled pipe 3 is connected to the jet source, and the other end is placed in a reverberation Inside the box 1; the damping box 31 is installed on the body of the water-filled pipeline 3, the damping box 31 is made of iron sheet processing, double-layer semi-cylindrical shell structure, no top cover, there are lugs at the two ends of the semi-cylindrical shell, There are four through holes on the lug, the shock absorber 31 is 200mm long, the inner diameter is 108mm, the shell thickness is 3mm, and the radial distance between the inner surface of the inner shell and the outer surface of the outer shell is 106mm. The inner side of the vibrating box 31 is attached to the pipe body of the water-filled pipeline 3, the lugs are opposite, and the four through holes on the lugs are aligned, and the double-ended studs and nuts 34 are used to fasten the vibration-absorbing box 31 tightly on the filling pipe. On the water pipeline 3, iron sand is filled in the vibration damping box 31. The surface of the filled iron sand is flush with the top of the vibration damping box 31. Five pairs of vibration damping boxes 31 are installed on the water filling pipeline 3. Two vibration damping boxes The distance between 31 is 100mm, and the included angle between the connection line formed by the lugs of two damping boxes 31 and the connection line formed by the lugs of other damping boxes 31 is 72 degrees, that is, the vibration damping box 31 The lugs are arranged in a staggered manner; at the nozzle of the water-filled pipeline 3, a nozzle clamp 32 is installed, and the nozzle clamp 32 is a semi-circular structure with a thickness of 20mm, an inner diameter of 108mm, and an outer diameter of 208mm, that is, the inner and outer circles The radial distance of the ring is 100 mm, and there are lugs at both ends of the nozzle fixture 32, and through holes are opened on the ears, and through holes are opened on the nozzle fixture 32, and the through holes on the fastened nozzle fixture 32 The center is aligned with the center of the threaded hole on the baffle 33, and two spout clamps 32 are pasted near the spout of the water-filled pipeline 3, and the distance between the plane of the spout clamp 32 and the plane of the spout is the thickness of the baffle 33 , the lugs of the nozzle fixture 32 are opposite, and the studs and nuts 35 are used to tighten, so that the nozzle fixture 32 is close to the nozzle of the water-filled pipeline 3; a barrier is installed at the nozzle of the water-filled pipeline 3 Plate 33, the baffle plate 33 is a ring structure with a thickness of 20mm, an inner diameter of 108mm, and an outer diameter of 324mm. There are threaded holes on the baffle plate 33, and the positions of the threaded holes match the positions of the through holes on the nozzle fixture 32. The baffle 33 is placed near the nozzle of the water-filled pipeline 3, and after the bolt 36 is used to pass through the through hole on the nozzle clamp 32, the baffle 33 is fastened on the nozzle clamp 32. At this time, the baffle 33 The lower surface is flush with the plane of the nozzle of the water-filled pipeline 3, and the gap between the baffle plate 33 and the nozzle of the water-filled pipeline 3 is coated with a sealant (type: 704), and then scraped flat with a paper knife , so that there is no gap between the baffle plate 33 and the nozzle of the water-filled pipeline 3 .

The iron sand filled in the damping box 31 has a particle size ranging from 0.2 mm to 2 mm.

Described hydrophone vertical line array 4 is made up of eight hydrophones 41, and hydrophone is the 8103 model of B&K company, utilizes coupling cavity reciprocal calibration method to carry out consistency calibration to the amplitude and phase of hydrophone 41, water The total length of the vertical line array 4 of the earphones is 1.4m, and the hydrophones 41 are arranged at equal intervals according to the interval of 0.2m. The hydrophones 41 are fixed on a soft and extremely elastic rope with nylon cable ties, and the bottom end of the rope is Hang a lead weight, and use the weight of the lead weight to straighten the rope. The cables of each hydrophone 41 need to be fastened on the rope with nylon cable ties according to the interval of 0.1m; The position in the reverberation box shown in 8 is placed; the other end of the hydrophone vertical line array 4 is connected to data acquisition and analysis equipment (not shown in this embodiment).

The test area in the reverberation box is 3.6m long, 3m wide, and 1.7m high. Five equidistant measuring points are selected in the length direction with a distance of 0.4m, and four equidistant measuring points are selected in the width direction with a distance of 0.33m, so there are a total of 20 measuring points in the reverberation box.

In Figures 1 to 7, 1 is a reverberation box, 2 is a plexiglass plate, 3 is a water-filled pipe, 31 is a damping box, 32 is a nozzle clamp, 33 is a baffle, and 34 is a stud and a nut , 35 is a stud and a nut, 36 is a bolt, 4 is a vertical line array of a hydrophone, and 41 is a hydrophone.

As shown in Figure 8, a water-filled pipeline jet noise measurement system and measurement method, the steps of the measurement method are as follows:

Step S1: Fill the reverberation box 1 with water, and measure the background noise at different spatial measuring points in the test area through the hydrophone vertical line array 4 in the test area according to the measuring point positions shown in Figure 7, And sum and average the background noise at different spatial measuring point positions;

Step S2: hang the transmitting transducer at the center of the jet area of the reverberation box 1, and measure the test in the test area of the reverberation box 1 through the vertical line array 4 of the hydrophone according to the position of the measuring point shown in Figure 7 The sound pressure power spectrum and reverberation time of the sound source at different spatial measuring point positions in the area, and the sound source sound pressure power spectrum and reverberation time at different spatial measuring point positions are summed and averaged;

Step S3: After installing the damping box 31, the nozzle fixture 32 and the baffle 33 on the water filling pipeline 3, the nozzle of the water filling pipeline 3 and the upper surface of the baffle 33 have just been immersed in the water surface, and the jet source is turned on to make the filling The water in the water pipe 3 is sprayed into the jet area of the reverberation box 1 at a certain speed, and the overflowing water is led out through the diversion device of the reverberation box 1;

Step S4: Measure the sound pressure power spectrum of the underwater jet formed by the water-filled pipeline 3 in the test area of the reverberation box 1 through the vertical line array 4 of the hydrophone according to the position of the measuring point shown in Figure 7, and compare the different The sound pressure power spectrum at the position of the spatial measuring point is summed and averaged;

Step S5: Use the sound pressure power spectrum data and reverberation time data of the transmitting transducer under the free field condition to obtain the room constant of the reverberation box 1, and correct the sound pressure power spectrum in step S4 to obtain the full The free-field equivalent sound pressure level and radiated sound power of the underwater jet in water pipe 3.

The present invention uses the water-filled reverberation box 1 placed in the air to measure the jet flow noise of the water-filled pipeline 3, and uses the good acoustic reflection of the box wall to store the jet radiation sound energy of the water-filled pipeline 3 well in the reverberation box 1; use the plexiglass plate 2 to divide the reverberation box 1 into a jet area and a test area, because the characteristic impedance of the plexiglass plate 2 is close to that of water, the jet sound energy in the jet area can be well transmitted to the test area, and The hydrophone in the test area is in still water and is not affected by the water flow caused by the jet; the vibration of the wall of the water-filled pipeline 3 is well weakened by using the vibration-absorbing box 31; the water-filled pipeline 3 is placed in the reverberation box 1 At the water surface position in the inner jet flow area, the acoustic radiation capability of the nozzle is reduced by using the absolute soft boundary acoustic condition of the water surface; the nozzle clamp 32 and the baffle 33 are used to eliminate the influence of the eddy current noise caused by the impact of the nozzle water flow; The method of moving the hydrophone vertical line array 4 to collect the jet noise of the water-filled pipeline 3 eliminates the need for hydrophones and hydrophone cables when the hydrophones and hydrophone cables are used for spatial averaging in the underwater reverberation method. During operation, low-frequency noise interference caused by jitter, and flow noise interference caused by relatively static water movement during operation; using the reverberation method to measure the jet noise of the water-filled pipeline, the test implementation is easier and the workload of the measurement is reduced .

Claims (7)

1. the measurement system of a water-filled pipe jet noise, it is characterised in that: include water-filled pipe, reverberation box, poly (methyl methacrylate) plate and hydrophone vertical linear array；

Reverberation box is steel rectangular structure, internal water-filling, and top uncovered, bottom adopts cross beam support；Poly (methyl methacrylate) plate is arranged on inside reverberation box, and reverberation box is divided into two parts: fluerics and test section；Water-filled pipe is placed on the fluerics of reverberation box；Hydrophone vertical linear array is placed on the test section in reverberation box.

2. the measurement system of a kind of water-filled pipe jet noise according to claim 1, it is characterized in that: the pipe shaft of described water-filled pipe installs N to vibration damping box, vibration damping box is double-deck semicolumn shell structure, without top cover, the internal diameter of vibration damping box and the external diameter of water-filled pipe are identical, and there is lug at the two ends of double-deck semicolumn shell structure, lug has through hole, the lug of every pair of vibration damping box is relative, connects at lug place, the internal filling iron ore of vibration damping box.

3. the measurement system of a kind of water-filled pipe jet noise according to claim 1, it is characterized in that: the mouth of pipe of described water-filled pipe is provided with a line up fixture, mouth of pipe fixture is semicircular ring structure, the internal diameter of mouth of pipe fixture and the external diameter of water-filled pipe are identical, the outside of mouth of pipe fixture is with lug, having through hole, the lug of two mouth of pipe fixtures is relative, connects at lug place.

4. the measurement system of a kind of water-filled pipe jet noise according to claim 1, it is characterised in that: the mouth of pipe of described water-filled pipe is provided with baffle, and baffle is connected with mouth of pipe fixture；The internal diameter of baffle and the external diameter of water-filled pipe are identical, and the lower surface of baffle and the mouth of pipe of water-filled pipe are generally flush with.

5. the measurement system of a kind of water-filled pipe jet noise according to claim 1, it is characterized in that: a termination jet source of described water-filled pipe, the other end of water-filled pipe is placed on the center, fluerics of reverberation box, the axis of water-filled pipe is perpendicular to the water surface in reverberation box, and the mouth of pipe of water-filled pipe and the upper surface of baffle are immersed under water.

6. the measurement system of a kind of water-filled pipe jet noise according to claim 4, it is characterised in that: the external diameter of described baffle is three times of pipe external diameter.

7. the measuring method based on the measurement system of the water-filled pipe jet noise described in claim 1, it is characterised in that: comprise the following steps,

Step one: by water-filling in reverberation box, measures the background noise at point position place of reverberation box build-in test district by hydrophone vertical linear array, and is undertaken the background noise of different measuring points position suing for peace, on average；

Step 2: the center of fluerics hangs transmitting transducer in reverberation box, measured the acoustic pressure power spectrum at point position place of reverberation box build-in test district, reverberation time by hydrophone vertical linear array, and to the acoustic pressure power spectrum of different measuring points position and the reverberation time sues for peace, on average；

Step 3: after water-filled pipe is installed vibration damping box, mouth of pipe fixture and baffle, the mouth of pipe of water-filled pipe is placed near the water surface so that the water in water-filled pipe is with in speed K injection to the fluerics of reverberation box, and the water of overflow is derived by the guiding device of reverberation box；

Step 4: measured the acoustic pressure power spectrum of the submerged jet noise of the water-filled pipe formation at point position place by hydrophone vertical linear array in reverberation box；

Step 5: utilize the room constant of the transmitting transducer acoustic pressure power spectrum data in free field and reverberation time data calculating reverberation box, acoustic pressure power spectrum in S4 step is modified, then obtains the equivalent free field sound pressure level of water-filled pipe submerged jet noise and the radiated of free field.