阅读说明：本技术 一种带拉瓦尔喷管的哈特曼声波发生器 (Hartmann sound generator with laval nozzle ) 是由 齐江龙 陈雅曦 张卫红 杨美宁 刘时秀 王明杰 呙道军 范博超 王磊 李培星 于 于 2020-12-23 设计创作，主要内容包括：本发明提出一种带拉瓦尔喷管的哈特曼声波发生器,包括拉瓦尔喷管和谐振腔,拉瓦尔喷管用于喷射出高压高速气体,所述谐振腔的深度具有可调节性,所述谐振腔具有贯通的腔体,所述谐振腔背离拉瓦尔喷管的一端设置调节杆,所述调节杆一端的杆帽内置于所述腔体内,所述调节杆另一端的杆柄至少一部分位于所述腔体外部；调节杆能够在所述谐振腔内调节深度位置。本发明将哈特曼哨的普通喷口改进为拉瓦尔喷管,有效提升哈特曼哨的发声效率。进一步的,本发明将哈特曼哨的谐振腔改为可调节深度的谐振腔,可满足发出不同的特定声波频率的要求。(The invention provides a Hartmann sound generator with a Laval nozzle, which comprises the Laval nozzle and a resonant cavity, wherein the Laval nozzle is used for ejecting high-pressure high-speed gas, the depth of the resonant cavity is adjustable, the resonant cavity is provided with a through cavity, one end of the resonant cavity, which is far away from the Laval nozzle, is provided with an adjusting rod, a rod cap at one end of the adjusting rod is arranged in the cavity, and at least one part of a rod handle at the other end of the adjusting rod is positioned outside the cavity; the adjusting rod can adjust the depth position in the resonant cavity. The invention improves the common nozzle of the Hartmann whistle into the Laval nozzle, thereby effectively improving the sound production efficiency of the Hartmann whistle. Furthermore, the invention changes the Hartmann resonant cavity into a resonant cavity with adjustable depth, which can meet the requirements of emitting different specific sound wave frequencies.)

1. The Hartmann sound generator with the Laval nozzle is characterized by comprising the Laval nozzle and a resonant cavity, wherein the Laval nozzle is used for ejecting high-pressure high-speed gas, the front end of the Laval nozzle is connected with a high-pressure gas source through a threaded connection pipeline, the depth of the resonant cavity is adjustable, the resonant cavity is provided with a through cavity, one end of the resonant cavity, which is far away from the Laval nozzle, is provided with an adjusting rod, a rod cap at one end of the adjusting rod is arranged in the cavity, at least one part of a rod handle at the other end of the adjusting rod is positioned outside the cavity, and the diameter of the cavity is equal to that of an outlet of the Laval nozzle; the adjusting rod can adjust the depth position in the resonant cavity.

2. The Hartmann acoustic generator with the Laval nozzle as claimed in claim 1, wherein a through hole for the rod handle to pass through is formed in the cavity at the side away from the Laval nozzle, the diameter of the through hole is smaller than that of the rod cap, and the diameter of the rod cap is matched with that of the cavity.

3. The Hartmann acoustic wave generator with the Laval nozzle of claim 2, wherein the stem cap and the stem handle are integrally formed, and the stem handle is provided with a plurality of through holes perpendicular to the center line of the stem handle.

4. The Hartmann acoustic generator with the Laval nozzle as claimed in claim 3, wherein a cavity is formed at one end of the cavity, which is far away from the Laval nozzle, adjacent to the through hole, a through hole penetrating through the cavity is formed in the outer wall of the resonant cavity, the center line of the through hole is perpendicular to the center line of the resonant cavity, a positioning pin is accommodated in the through hole, and the positioning pin is further inserted into the through hole.

5. The hartmann sound generator with a laval nozzle as claimed in claim 1, wherein the laval nozzle is made of stainless steel and is formed by integral processing.

6. The Hartmann acoustic wave generator with a Laval nozzle of claim 4, wherein the locating pin is stainless steel.

7. The hartmann sound generator with a laval nozzle of claim 1, wherein the total sound pressure level of the sound wave from the high pressure gas source is adjustable.

8. The Hartmann acoustic wave generator with a Laval nozzle as claimed in claim 4, wherein, under the condition that the diameter of the outlet of the Laval nozzle is equal to the diameter of the resonant cavity, based on Helmholtz's resonance theory, the empirical formula of the sound frequency f is as follows:

in the formula (1), c is the sound velocity, and 340m/s is taken; h is the depth of the resonant cavity and d is the diameter of the resonant cavity.

9. The hartmann sound generator with a laval nozzle as set forth in claim 8, wherein the maximum depth of the resonant cavity is greater than a depth to which the minimum sound frequency f is to be satisfied.

10. A hartmann sound generator with a laval nozzle as claimed in claim 9, wherein the maximum depth of the resonant cavity is not more than 10 times the diameter d of the resonant cavity.

Technical Field

The invention relates to a Hartmann sound generator with a Laval nozzle, belonging to the technical field of sound generators.

Background

At present, a noise transducer mainly used in the field of aerospace noise environment tests is an electric airflow loudspeaker. Due to the operating principle, it is difficult to modulate the airflow at frequencies above 1KHz, and the mid-high frequency region acoustic energy is generated by a combination of cold air jet noise and harmonic distortion from the lower frequency modulation. Therefore, the sound production efficiency in the middle-high frequency band is very low, and the sound spectrum with high requirements for partial middle-high frequency is difficult to meet the requirements.

Meanwhile, with the continuous emergence of various novel carrier rockets and weaponry in China, the noise environment is more and more severe, so the load requirement on the noise environment test is higher and higher. And with the increase of the model volume, the volume of the reverberation chamber required by the noise test is larger and larger, and the high-frequency loading of the large-volume reverberation chamber is more difficult, so that certain compensation needs to be performed on the high-frequency loading of the sound field in the test.

The Hartmann whistle is a hydrodynamic sound wave generator proposed by Hartmann of Denmark in 1918, and has the advantages of simple structure, small volume, impact resistance, capability of working under severe conditions and the like. Powerful acoustic radiation can be generated at higher pressures as long as the material strength conditions permit. Meanwhile, the Hartmann sounder also has the characteristics of low manufacturing cost, large treatment capacity, convenient operation, durability and the like, and is widely applied to the aspects of sound wave ash removal, blockage removal, scale prevention, wax prevention, viscosity reduction, chemical reaction acceleration, airplane impact noise suppression, cavity noise suppression and the like.

The Hartmann whistle is mainly composed of a jet cavity and a resonant cavity. Hartmann et al summarized the Hartmann whistle sound mechanism, whereby fluid is ejected from the ejection chamber at a constant velocity to form an unstable pressure field in front of the nozzle, a resonant cavity is placed within the pressure field, and the ejection chamber and the resonant cavity form a resonant system. The fluid ejected from the ejection cavity generates a periodic inflation process on the resonant cavity, so that the feedback flow pressure of the resonant cavity gradually rises, and the fluid fed back from the resonant cavity collides with the ejected fluid to emit sound waves.

Laval nozzles are generally common components of rocket engines and aircraft engines. Referring to fig. 1, the laval nozzle is composed of a contraction section 2 and an expansion section 4, wherein the contraction section 2 contracts to a throat portion 3 from small to small, the expansion section 4 is arranged behind the throat portion 3, and the pipe diameter expands outwards from small to large. The Laval nozzle is invented by Laval of Sweden, and the working principle is that gas flows into a contraction section of the Laval nozzle under the action of certain pressure, and at the stage, the gas movement follows the movement rule that the gas flow rate is in inverse proportion to the pipeline section area, so that the gas flow is accelerated continuously; when the airflow reaches the throat, the flow velocity is close to or reaches the sonic velocity, and when the transonic gas moves in the pipe, the section is increased, and the flow velocity is accelerated. Therefore, the Laval nozzle plays a role of a 'flow velocity amplifier' in the whole flowing process of the gas, the gas velocity can be correspondingly changed along with the change of the sectional area of the nozzle, and the gas flow velocity can be improved from subsonic velocity to supersonic velocity, even hypersonic velocity.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects and requirements in the prior art, the invention provides a Hartmann sound generator with a Laval nozzle, which improves the common nozzle of a Hartmann whistle into the Laval nozzle, and effectively improves the sound production efficiency of the Hartmann whistle. Furthermore, the invention changes the Hartmann resonant cavity into a resonant cavity with adjustable depth, which can meet the requirements of emitting different specific sound wave frequencies.

(II) technical scheme

A Hartmann sound generator with a Laval nozzle comprises the Laval nozzle and a resonant cavity, wherein the Laval nozzle is used for ejecting high-pressure high-speed gas, the front end of the Laval nozzle is connected with a high-pressure gas source through a threaded connection pipeline, the depth of the resonant cavity is adjustable, the resonant cavity is provided with a through cavity, one end of the resonant cavity, which is far away from the Laval nozzle, is provided with an adjusting rod, a rod cap at one end of the adjusting rod is arranged in the cavity, at least one part of a rod handle at the other end of the adjusting rod is positioned outside the cavity, and the diameter of the cavity is equal to the diameter of an outlet of the Laval nozzle; the adjusting rod can adjust the depth position in the resonant cavity.

And a through hole for the rod handle to pass through is formed in one side, which is far away from the Laval nozzle, of the cavity, the diameter of the through hole is smaller than that of the rod cap, and the diameter of the rod cap is matched with that of the cavity.

The rod cap and the rod handle are integrally formed, and the rod handle is provided with a plurality of through holes which are vertical to the central line of the rod handle.

One end of the cavity, which is far away from the laval nozzle, is adjacent to the through hole to form a cavity, a through hole penetrating through the cavity is formed in the outer wall of the resonant cavity, the center line of the through hole is perpendicular to the center line of the resonant cavity, a positioning pin is accommodated in the through hole, and the positioning pin is further arranged in the through hole in a penetrating mode.

The laval nozzle is made of stainless steel and is integrally processed.

The locating pin is stainless steel.

The high pressure gas source has adjustability to the total sound pressure level of the sound waves.

Under the condition that the diameter of the outlet of the Laval nozzle is equal to that of the resonant cavity, based on Helmholtz's resonance theory, the empirical formula of the sound frequency f is as follows:

in the formula (1), c is the sound velocity, and 340m/s is taken; h is the depth of the resonant cavity and d is the diameter of the resonant cavity.

The maximum depth of the resonant cavity is larger than the depth which needs to be met by the minimum sound frequency f.

The maximum depth of the resonant cavity is not more than 10 times the diameter d of the resonant cavity.

(III) advantageous effects

The Hartmann sound generator with the Laval nozzle improves the common nozzle of the Hartmann whistle into the Laval nozzle, so that the sound production efficiency of the Hartmann whistle is effectively improved. Furthermore, the invention changes the Hartmann resonant cavity into a resonant cavity with adjustable depth, which can meet the requirements of emitting different specific sound wave frequencies.

Drawings

FIG. 1 is a schematic view of a prior art Laval nozzle configuration.

FIG. 2 is a schematic structural diagram of a Hartmann sound generator with a Laval nozzle according to the present invention.

In the figure, 1-inlet; 2-a contraction section; 3-throat; 4-an expansion section; 5-an outlet; 6-Laval nozzle; 7-a resonant cavity; 8-adjusting the rod; 9-a positioning pin; 10-a stem handle; 11-rod cap.

Detailed Description

The Hartmann sound generator with the Laval nozzle comprises the Laval nozzle 6 and a resonant cavity 7, wherein the Laval nozzle 6 is used for ejecting high-pressure high-speed gas, the front end of the Laval nozzle 6 is connected with a high-pressure gas source through a threaded connection pipeline, the depth of the resonant cavity 7 is adjustable, the resonant cavity 7 is provided with a through cavity, one end of the resonant cavity 7, which is far away from the Laval nozzle 6, is provided with an adjusting rod 8, a rod cap 11 at one end of the adjusting rod 8 is arranged in the cavity, at least one part of a rod handle 10 at the other end of the adjusting rod 8 is positioned outside the cavity, and the diameter of the cavity is equal to that of an outlet 5 of the Laval nozzle 6; the adjustment rod 8 is capable of adjusting the depth position within the resonant cavity 7.

A through hole for the rod handle 10 to pass through is formed in one side, which is far away from the Laval nozzle 6, in the cavity, the diameter of the through hole is smaller than that of the rod cap 11, and the diameter of the rod cap 11 is matched with that of the cavity.

The rod cap 11 and the rod handle 10 are integrally formed, and the rod handle 10 is provided with a plurality of through holes which are vertical to the central line of the rod handle 10.

One end of the cavity, which is far away from the laval nozzle 6, is adjacent to the through hole to form a concave cavity, a through hole penetrating through the concave cavity is formed in the outer wall of the resonant cavity 7, the center line of the through hole is perpendicular to the center line of the resonant cavity 7, a positioning pin 9 is accommodated in the through hole, and the positioning pin 9 is further arranged in the through hole in a penetrating mode.

The laval nozzle 6 is made of stainless steel and is integrally machined.

The positioning pin 9 is made of stainless steel.

The high pressure gas source has adjustability to the total sound pressure level of the sound waves.

In the case where the diameter of the outlet 5 of the laval nozzle 6 is equal to the diameter of the resonant cavity 7, based on the resonance theory of Helmholtz, the empirical formula of the sound frequency f is:

in the formula (1), c is the sound velocity, and 340m/s is taken; h is the depth of the resonant cavity and d is the diameter of the resonant cavity 7.

The maximum depth of the resonant cavity 7 is greater than the depth which the minimum sound frequency f needs to satisfy.

The maximum depth of the resonant cavity 7 is not more than 10 times the diameter d of the resonant cavity 7.