Implementation Methods for Studying Silent Pollution Water Jet Generator and Water Jet Noise Performance

Abstract

This invention discloses a silent pollution-free water jet generator and a method for studying the noise performance of water jets. The silent pollution-free water jet generator includes, in sequence, a first elbow, a first transition pipe, a solenoid valve / flowmeter assembly, a second transition pipe, a second elbow, and a nozzle section, all sealed together. One end of the first elbow is sealed to an outlet on one side of the housing. The method for studying the noise performance of the water jet comprises the following steps: Step 1: Determine the vertical distance between the bottom surface of the housing and the center of the nozzle section; Step 2: Assemble the silent pollution-free water jet generator and hoist the housing onto a platform frame, adjusting the frame height to meet the testing requirements; Step 3: Fill the housing with water; Step 4: Obtain the water jet velocity, and begin measuring the noise after reaching the required velocity. This invention uses water gravity to generate a water jet to study its noise performance, significantly reducing interference caused by the noise of the device itself.

Description

Technical Field

[0001] This invention relates to a noiseless water jet generator and a method for studying the noise performance of water jets, used to generate water jets for studying their noise performance, and belongs to the field of fluid machinery. Background Technology

[0002] The noise performance of water jets is of significant research value in certain fields. Currently, most water jet generators used to study water jet noise pressurize a water tank using mechanical pressurization devices (air compressors, booster pumps, etc.), and then generate a water jet at a certain velocity through pipelines. When generating water jets in this way, the noise generated by the mechanical pressurization device itself often affects the study of water jet noise performance, especially at low water jet velocities where the jet noise itself is relatively low, making it difficult to meet the signal-to-noise ratio requirements; secondly, the device structure is relatively complex and costly. Summary of the Invention

[0003] The technical problem to be solved by this invention is: how to reduce the impact of the device's own noise on the water jet noise when the water jet velocity is low, and to simplify the structure and reduce costs.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is to provide a silent pollution water jet generating device, characterized in that it includes a first elbow, a first transition pipe, a solenoid valve / flowmeter assembly, a second transition pipe, a second elbow, and a nozzle section connected in sequence and sealed. One end of the first elbow is sealed to the water outlet opened on one side of the housing.

[0005] Preferably, the inner sidewall of the tank is equipped with a liquid level gauge, with the bottom of the tank as the 0 mark.

[0006] Preferably, the first and second transition pipes are both vertically downward, the nozzle section is horizontally positioned, and the housing is horizontally positioned; the inner side of the housing is a rectangular cavity without a top cover.

[0007] A method for studying the noise performance of a water jet, characterized by using the noiseless water jet generator as described in claim 3, comprising the following steps:

[0008] Step 1: Determine the vertical distance L between the outer side of the bottom plate of the housing and the center of the nozzle section;

[0009] Step 2: Assemble the silent pollution water jet generator, hoist the housing onto the water platform frame, and adjust the height of the frame to meet the test conditions.

[0010] Step 3: Fill the tank with water until the water level inside the tank meets the following requirements: ensure stable flow in the pipe when the test water velocity is reached;

[0011] Step 4: Observe the flow meter of the solenoid valve / flow meter assembly. Based on the conservation of flow, calculate the water jet velocity V. After the required water jet velocity is reached, start measuring the noise.

[0012] Preferably, in step one, before determining the vertical distance L between the outer side of the bottom plate of the housing and the center of the nozzle section, the water jet velocity V generated at the nozzle section must first be calculated:

[0013] According to Bernoulli's equation, the velocity V of the water jet generated at the nozzle section can be calculated by the following formula:

[0014]

[0015] In the above formula, g is the local gravitational acceleration; H I This represents the head height required for the jet velocity to reach V under ideal conditions.

[0016] Preferably, the head loss ΔH caused by the pipeline is taken into account, and ΔH is approximately estimated according to the following formula:

[0017] △H=(0.01×H I / d+0.06)×V 2 / 2 / g (2)

[0018] In the above formula, d is the inner diameter of the nozzle section (7).

[0019] Preferably, in step three, the water level inside the tank needs to exceed a predetermined water level h.

[0020] Preferably, the required actual head height H R =H I +△H,

[0021] Depending on whether the nozzle centerline is above or below the free surface, it is divided into two cases: above-water or underwater jetting. H R The following relationship must be satisfied:

[0022] H R =h + t + L Water jetting, hw ≥ 0

[0023] H R =h+t+L+hw underwater jet, hw<0 (3)

[0024] In the above formula, L is the vertical distance from the center of the nozzle in the nozzle section to the outer side of the bottom plate of the box; h is the height of the liquid level N in the box, satisfying h < D; t is the thickness of the bottom plate of the box; hw is the vertical distance from the center of the nozzle section to the external free liquid level, which is positive when the center line of the nozzle section is above the free liquid level and negative otherwise. When the free liquid level coincides with the nozzle center, i.e., hw = 0; According to equations (1) to (3), the pipeline length required to reach the injection speed V at a certain injection height hw can be initially calculated, that is, the vertical distance L between the outer side of the bottom plate of the box and the center of the nozzle section. The length of L can be adjusted by the length L1 of the second transition pipe.

[0025] Preferably, the inner side of the box is in the shape of a cuboid with a length and width of X and a depth of D; the maximum water level in the box cannot exceed D; by replacing the nozzle section, the influence of the nozzle shape or the injection flow rate Q on the water jet can be studied, and the flow rate Q can be directly obtained through the solenoid valve / flow meter assembly.

[0026] Preferably, the water jet velocity decreases as the liquid level in the box decreases. The percentage of the relative decrease in the water jet velocity per unit time is estimated by the following formula:

[0027]

[0028] In the above formula, △V is the decrease in the water jet velocity per unit time;

[0029] According to the calculation of equation (4), the relative change in the water jet velocity per unit time is within 0.1% to meet the test requirements.

[0030] The present invention generates a water jet based on water gravity without the aid of a mechanical pressurization device to study the noise performance of the water jet. By means of this device, the interference caused by the noise of the device itself can be greatly reduced. Especially for low-speed water jets, the influence of the noise of the device itself on the water jet noise can be greatly reduced. The present invention has the advantages of low noise, simple structure and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic structural diagram of a silent pollution water jet generating device;

[0032] Figure 2 It is a partial cross-sectional view of a silent pollution water jet generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] To make the present invention more obvious and understandable, the preferred embodiments are described in detail below in conjunction with the accompanying drawings.

[0034] This invention provides a silent, pollution-free water jet generator that generates a water jet by relying on the gravity of the water itself, thus ensuring low noise performance. As shown in Figure 1, it consists of an elbow 1, a housing 2, a transition pipe 3, a solenoid valve / flowmeter assembly 4, a second transition pipe 5, a second elbow 6, a nozzle section 7, and a liquid level gauge 8.

[0035] like Figure 1 , Figure 2 As shown, the inner side of the tank 2 is a cuboid shape with length and width both X and depth D. A liquid level gauge 8 is installed on the inner side wall of the tank 2, with the bottom of the tank 2 as the 0 mark. An outlet is located on one side of the tank 2. Elbow 1 is connected to the outlet via a thread. Transition pipe 3 is connected to elbow 1 via a thread, ensuring that transition pipe 3 is vertically downwards after connection. All other components (solenoid valve / flowmeter assembly 4, transition pipe 2 5, elbow 2 6, and nozzle section 7) are connected via threads. That is, the solenoid valve / flowmeter assembly 4, transition pipe 2 5, elbow 2 6, and nozzle section 7 are connected sequentially. The lower end of transition pipe 3 is connected to the solenoid valve / flowmeter assembly 4.

[0036] For the device of the present invention, according to Bernoulli's equation, the water jet velocity V generated at nozzle section 7 can be calculated by the following formula:

[0037]

[0038] In the above formula, g is the local gravitational acceleration; H I This represents the head height required to achieve a jet velocity of V under ideal conditions. Considering the head loss ΔH caused by the pipeline, ΔH is approximately estimated using the following formula:

[0039] △H=(0.01×H I / d+0.06)×V 2 / 2 / g (2)

[0040] In the above formula, d is the inner diameter of the nozzle section 7.

[0041] Therefore, the actual head height H required by the device of the present invention R =H I +△H. Depending on whether the nozzle centerline is above or below the free surface, it is divided into two cases: above-water or underwater jetting. H R The following relationship must be satisfied.

[0042] H R =h + t + L Water jetting, hw ≥ 0

[0043] H R =h+t+L+hw underwater jet, hw<0 (3)

[0044] In the above formula, L is the vertical distance from the center of the nozzle to the outer side of the bottom plate of the box; h is the height of the liquid level N in the box, satisfying h < D; t is the thickness of the bottom plate of the box 2; hw is the vertical distance from the center of the nozzle section 7 to the external free liquid surface ( Figure 2 at point A or point B in), with the center line of the nozzle section 7 above the free liquid surface ( Figure 2 at the position of point B in) being positive and vice versa ( Figure 2 at the position of point A in). When the free liquid surface coincides with the nozzle center, i.e., hw = 0. According to equations (1) to (3), the pipeline length (i.e., the vertical distance or height between the outer side of the bottom plate of the box 2 and the center of the nozzle section 7) required to reach the injection speed V at a certain injection height hw can be preliminarily calculated, that is, L is determined. The length of L can be adjusted by the length L1 of the transition pipe 2. Among them: A is the free liquid surface (underwater injection situation); B is the free liquid surface (above-water injection situation).

[0045] Replacing the nozzle section 7 (i.e., changing the nozzle shape or the inner diameter d of the nozzle) can study the influence of the nozzle shape or the injection flow rate Q on the water jet. Among them, the flow rate Q can be directly obtained through the solenoid valve / flowmeter assembly 4.

[0046] Due to the characteristics of the device of the present invention, the water jet speed will decrease as the liquid level in the box 2 decreases. The percentage of the relative decrease in the water jet speed per unit time is estimated by the following formula.

[0047]

[0048] In the above formula, △V is the decrease in the water jet speed per unit time;

[0049] According to equation (4), select appropriate values of X, d, and H R such that the relative change in the water jet speed per unit time is within 0.1%. Generally speaking, the larger X is and the smaller d is, the less the change in the water jet speed.

[0050] When conducting water jet research using the device of the present invention, it is implemented according to the following steps:

[0051] a) According to the required V and hw, the pipeline length can be determined according to equations (1) to (3). It should be noted during the calculation that the maximum water level in the box cannot exceed D. At the same time, according to the calculation of equation (4), select appropriate X and d such that the change in the water jet speed per unit time is within 0.1% to meet the test requirements;

[0052] b) Assemble the device, hoist the box onto the horizontal bench, and adjust the bench height to meet the requirements of the test conditions;

[0053] c) Inject water into the box, generally exceeding the established water level h to ensure stable flow in the pipe when reaching the test water speed;

[0054] d) Observe the flow meter, calculate the water jet velocity V according to the law of conservation of flow, and start measuring the noise after the required water jet velocity is reached.

Claims

1. A method for studying the noise performance of a water jet, characterized in that, Using a silent polluted water jet generating device, the silent polluted water jet generating device includes an elbow one (1), a transition pipe one (3), a solenoid valve / flow meter assembly (4), a transition pipe two (5), an elbow two (6), and a nozzle section (7) that are sequentially and hermetically connected. One end of the elbow one (1) is hermetically connected to the water outlet opened on one side of the box body (2). Both the transition pipe one (3) and the transition pipe two (5) are arranged vertically downward, the nozzle section (7) is arranged horizontally, and the box body (2) is arranged horizontally. The inner side of the box body (2) is a cuboid cavity without a cover at the top. The implementation method steps for the research on the water jet noise performance are as follows: Step 1: Determine the vertical distance L between the outer side of the bottom plate of the box body (2) and the center of the nozzle section (7). Step 2: Assemble the silent polluted water jet generating device, hoist the box body (2) onto a horizontal bench, and adjust the height of the bench to meet the requirements of the test conditions. Step 3: Inject water into the box body (2) so that the water level in the box meets the following requirements: when reaching the test water velocity, ensure the stable flow in the pipe. Step 4: Observe the flow meter of the solenoid valve / flow meter assembly (4), and according to the law of conservation of flow, convert to obtain the water jet velocity V. After reaching the required water jet velocity, start measuring the noise. In the above Step 1, before determining the vertical distance L between the outer side of the bottom plate of the box body (2) and the center of the nozzle section (7), first calculate the water jet velocity V generated at the nozzle section (7): According to Bernoulli's equation, the water jet velocity V generated at the nozzle section (7) is calculated by the following formula: （1） In the above formula, g is the local gravitational acceleration; H I The ideal head height required for the jet velocity to reach V; Considering the head loss △H caused by the pipeline, △H is approximately estimated by the following formula: （2） In the above formula, d is the inner diameter of the nozzle of the nozzle section (7). In Step 3, the water level in the box body (2) needs to exceed the established water level h. The required actual head height H R =H I +△H, Depending on whether the nozzle centerline of the nozzle section (7) is above or below the free liquid surface, it can be divided into two cases: above-water or underwater jetting. R The following relationship must be satisfied: （3） In the above formula, L is the vertical distance from the nozzle center of the nozzle section (7) to the outer side of the bottom plate of the box body (2); h is the height of the liquid level in the box, satisfying h < D, where D is the depth of the box body (2); t is the thickness of the bottom plate of the box body (2); hw is the vertical distance from the center of the nozzle section (7) to the external free liquid level, with the center line of the nozzle section (7) above the free liquid level being positive and vice versa. When the free liquid level coincides with the nozzle center, that is, hw = 0. According to formulas (1) to (3), initially calculate the pipeline length required to reach the jet velocity V at a certain jet height hw, that is, the vertical distance L between the outer side of the bottom plate of the box body (2) and the center of the nozzle section (7). The length of L is adjusted by the length L1 of the transition pipe two (5).

2. The implementation method for studying the noise performance of a water jet as described in claim 1, characterized in that, A liquid level scale (8) is provided on the inner side wall of the box body (2), with the bottom of the box body (2) as the 0 scale position.

3. The implementation method for studying the noise performance of a water jet as described in claim 1, characterized in that, The inner side of the box body (2) is a cuboid shape with a length and width of X and a depth of D. The maximum water level in the box body (2) does not exceed D. Replace the nozzle section (7) to study the influence of the nozzle shape or the jet flow rate Q on the water jet, where the flow rate Q is directly obtained through the solenoid valve / flow meter assembly (4).

4. The implementation method for studying the noise performance of a water jet as described in claim 3, characterized in that, The water jet velocity will decrease as the liquid level in the box body (2) decreases. The percentage of the relative decrease in the water jet velocity per unit time is estimated by the following formula: （4） In the above formula, ΔV represents the decrease in the velocity of the water jet per unit time; According to formula (4), the relative change in water jet velocity per unit time is kept within 0.1% to meet the test requirements.

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