CN115043458A - Venturi cavitation test system and operation method - Google Patents
Venturi cavitation test system and operation method Download PDFInfo
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- CN115043458A CN115043458A CN202210576226.0A CN202210576226A CN115043458A CN 115043458 A CN115043458 A CN 115043458A CN 202210576226 A CN202210576226 A CN 202210576226A CN 115043458 A CN115043458 A CN 115043458A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/34—Treatment of water, waste water, or sewage with mechanical oscillations
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2301/00—General aspects of water treatment
- C02F2301/06—Pressure conditions
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Abstract
A Venturi cavitation test system comprises an annular flow passage consisting of a water storage tank, a flow rate control pump, a turbine section and a Venturi test section, wherein the turbine section is arranged in the direction of a water inlet end of the Venturi test section; the venturi testing section main body is a venturi tube and comprises a first straight tube section, a contraction section connected to the output end of the first straight tube section, a throat tube section connected to the tail end of the contraction section, a diffusion section connected to one end of the throat tube section and a second straight tube section connected to one end of the diffusion section; the inner wall of the diffusion section is in a trumpet-shaped variable cross section. By adopting the structure, the rotary turbine is arranged in front of the straight pipe section of the Venturi cavitator, the rotation of the turbine improves the water flow vorticity of the inlet section of the Venturi tube, reduces the influence of cavitation effect generated by cavitation on the wall surface, and the horn-shaped diffusion wall is arranged in the traditional Venturi hydrodynamic cavitation device, so that the cross section area of the flow dividing section generates nonlinear change, the length of a low-pressure area is further prolonged, and the cavitation efficiency is improved.
Description
Technical Field
The invention relates to the field of Venturi hydrodynamic cavitation, in particular to a Venturi cavitation test system and an operation method.
Background
As the fluid flows through the venturi throat, a low pressure region is created, which creates cavitation bubbles when its local pressure is below the saturation vapor pressure of the fluid at that temperature. The vacuole moves along with the main flow and collapses when reaching a high-pressure area to form a local hot spot, the local temperature can reach 1000-15000K, the local pressure can reach 100-5000 atm, water molecules can be promoted to generate OH with high activity and high oxidizability, and the destruction to the chemical bond of the organic pollutant can be realized. The application of the cavitation technology in the field of water treatment is wide, and the degradation of organic wastewater, the sterilization of drinking water and the like are realized by utilizing the cavitation effect and combining with the advanced oxidation technology.
In the process of cavitation test, the throat part of the Venturi tube has larger flow speed and is easy to generate cavitation under the given pressure difference condition by the existing cavitation generator with the Venturi tube structure, the smooth convergence section and the divergence section of the Venturi tube are favorable for promoting the formation of cavitation bubbles, but the cavitation reaction strength is lower, the cavitation effect is poor, the large-scale cavitation bubble collapse has larger influence on the expansion section, and the blockage and the material erosion are easy to generate. Therefore, the cavitation efficiency of the Venturi cavitation device is improved, and the influence of cavitation on the wall surface is reduced, so that the method has important significance for sewage treatment.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a venturi cavitation test system and an operation method, wherein a rotating turbine is arranged in front of a straight pipe section of a venturi cavitation device, the rotation of the turbine improves the water flow vorticity of the inlet section of the venturi tube, reduces the influence of cavitation effect generated by cavitation on the wall surface, and a horn-shaped diffusion wall is arranged in the traditional venturi hydrodynamic cavitation device, so that the cross section area of a flow dividing section generates nonlinear change, the length of a low-pressure area is further prolonged, and the cavitation efficiency is improved.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a Venturi cavitation test system comprises an annular flow passage consisting of a water storage tank, a flow rate control pump, a turbine section and a Venturi test section, wherein the turbine section is arranged in the direction of a water inlet end of the Venturi test section;
the venturi testing section main body is a venturi tube and comprises a first straight tube section, a contraction section connected to the output end of the first straight tube section, a throat tube section connected to the tail end of the contraction section, a diffusion section connected to one end of the throat tube section and a second straight tube section connected to one end of the diffusion section;
the inner wall of the diffusion section is in a trumpet-shaped variable cross section.
In a preferable scheme, the annular flow passage is also provided with an electric control valve and an electromagnetic flow meter.
In a preferred scheme, an insertion pipe section is arranged on the turbine section, a rotating shaft is inserted into the insertion pipe section, an impeller is arranged at one end of the rotating shaft, which is positioned in the pipeline, and one end of the rotating shaft, which is positioned outside the pipeline, is connected with the motor.
In a preferred scheme, the impeller is arranged close to the first straight pipe section in the Venturi test section.
In a preferred scheme, the flow rate control pump and the motor in the turbine section are connected to a variable frequency control cabinet.
In the preferred scheme, a first pressure gauge and a second pressure gauge are respectively arranged on pipelines at two ends of the Venturi test section.
In a preferable scheme, a high-speed camera is further arranged on one side of the Venturi testing section.
The operation method based on the Venturi cavitation test system specifically comprises the following steps:
1) opening the electric control valve to any opening degree, starting the flow rate control pump, continuously adding water into the water storage tank, circulating the system under a non-cavitation condition and discharging air remained in the system;
2) controlling the power and the lift of a flow rate control pump through a variable frequency control cabinet, changing the opening degree of an electric control valve, gradually increasing the inlet pressure of a system from 0 KPa to 500 KPa, increasing the pressure to 25 KPa, and recording the corresponding flow of an electromagnetic flowmeter;
3) visually observing the onset of cavitation in the venturi test section while monitoring the noise level associated with cavitation until the high speed camera is able to observe visual signs of cavitation;
4) and data acquisition is carried out through a high-speed camera.
In a preferable scheme, in the step 1), the dissolved oxygen in water is continuously measured at the position of the water storage tank through the dissolved oxygen probe, so that the oxygen content in the water is ensured to be maintained at 8g/m 3 The subsequent operation was carried out after an equilibrium concentration of (8 ppm).
In the preferable scheme, the inlet pressure of the Venturi test section is in the range of 0.3-0.5MPa, the outlet pressure is 0.1MPa, the convergence angle is 15 degrees, and the divergence angle is 6.2 degrees;
the pressure value is monitored through the first pressure gauge and the second pressure gauge.
In the system, the length of the throat section is 1/4 of the radius of the throat section;
the impeller in the turbine section is provided with five blades, the shape of each blade is determined by a Bezier curve, and the radial distance between the impeller and the inlet of the first straight pipe section is 0.3-0.4 times of the diameter of the first straight pipe section.
By adopting the structure and the method, the Venturi cavitation test system and the operation method provided by the invention have the following beneficial effects:
(1) the inner surface of each pipe section of the Venturi pipe is smooth, the diffusion section adopts the horn-shaped diffusion wall, compared with a linear flat wall surface, the horn-shaped diffusion wall is used for enabling the cross sectional area of the flow distribution section to generate nonlinear change, the change of the flow area along the diffusion section is relatively slow, the slow pressure recovery is converted into higher speed amplitude, the length of a low-pressure area is prolonged, the volume fraction of steam is remarkably increased, and the cavitation efficiency is further improved;
(2) the turbine section is arranged in front of the first straight pipe section of the Venturi pipe, when the turbine operates, the water flow vorticity at the inlet of the Venturi pipe is increased, the axial advance and retreat of the linear flow cavitation area are restrained, the length of the cavity is kept relatively fixed, and meanwhile, the cavitation area is moved to the center of the device by applying vortex, so that the cavitation phenomenon of the wall surface is reduced. In addition, the turbulence intensity increase caused by the vortex aggravates the water flow disturbance, so that OH generated in the cavitation process is further increased, and the water treatment effect capacity is further improved.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
fig. 1 is a schematic diagram of the overall structure of the system of the present invention.
FIG. 2 is a schematic diagram of the venturi test section of the present invention.
FIG. 3 is a schematic view of a turbine section configuration of the present invention.
In the figure: the device comprises a water storage tank 1, a flow rate control pump 2, an electric control valve 3, a variable frequency control cabinet 4, an electromagnetic flowmeter 5, a turbine section 6, a motor 601, an insertion pipe section 602, a rotating shaft 603, an impeller 604, a first pressure gauge 7, a Venturi test section 8, a first straight pipe section 801, a contraction section 802, a throat pipe section 803, a diffusion section 804, a second straight pipe section 805, a second pressure gauge 9 and a high-speed camera 10.
Detailed Description
Example 1:
as shown in fig. 1, a venturi cavitation test system comprises an annular flow channel consisting of a water storage tank 1, a flow rate control pump 2, a turbine section 6 and a venturi test section 8, wherein the turbine section 6 is arranged in the water inlet end direction of the venturi test section 8;
the main body of the Venturi test section 8 is a Venturi tube and comprises a first straight tube section 801, a contraction section 802 connected to the output end of the first straight tube section 801, a throat tube section 803 connected to the tail end of the contraction section 802, a diffusion section 804 connected to one end of the throat tube section 803 and a second straight tube section 805 connected to one end of the diffusion section 804;
the inner wall of the diffusion section 804 is flared and has a variable cross section.
In a preferable scheme, the annular flow passage is further provided with an electric control valve 3 and an electromagnetic flowmeter 5.
In a preferred scheme, an insertion pipe section 602 is arranged on the turbine section 6, a rotating shaft 603 is inserted into the insertion pipe section 602, an impeller 604 is arranged at one end of the rotating shaft 603 positioned in the pipeline, and one end of the rotating shaft 603 positioned outside the pipeline is connected with the motor 601.
In a preferred embodiment, the impeller 604 is disposed adjacent to the first straight section 801 of the venturi test section 8.
In a preferred scheme, the flow rate control pump 2 and the motor 601 in the turbine section 6 are connected to the variable frequency control cabinet 4.
In the preferred scheme, a first pressure gauge 7 and a second pressure gauge 9 are respectively arranged on pipelines at two ends of the Venturi test section 8.
In a preferred scheme, a high-speed camera 10 is further arranged on one side of the venturi testing section 8.
Example 2:
the operation method of the venturi cavitation test system based on embodiment 1 specifically includes the following steps:
1) starting the electric control valve 3 to any opening degree (non-full opening or full closing), starting the flow rate control pump 2, continuously adding water into the water storage tank 1, circulating the system under a non-cavitation condition and discharging air remained in the system;
2) controlling the power and the lift of the flow rate control pump 2 through the variable frequency control cabinet 4, changing the opening degree of the electric control valve 3, gradually increasing the inlet pressure of the system from 0 KPa to 500 KPa, increasing the pressure to 25 KPa, and recording the corresponding flow of the electromagnetic flowmeter 5;
3) the onset of cavitation in the venturi test section 8 is visually observed while monitoring the noise level associated with cavitation until the high speed camera 10 is able to observe visual signs of cavitation;
4) data acquisition is performed by the high-speed camera 10.
In a preferable scheme, in the process of the step 1), the dissolved oxygen in the water is continuously measured at the position of the water storage tank 1 through the dissolved oxygen probe, so that the oxygen content in the water is ensured to be maintained at 8g/m 3 The subsequent operation is carried out after the equilibrium concentration of (A).
In the preferred scheme, the inlet pressure of the Venturi test section 8 is in the range of 0.3-0.5MPa, the outlet pressure is 0.1MPa, the convergence angle is 15 degrees, and the divergence angle is 6.2 degrees;
the pressure value is monitored by a first pressure gauge 7 and a second pressure gauge 9.
Example 3:
during the above experiment:
when water flow enters the vortex section 6, the motor 601 drives the impeller 604 to rotate, the rotating speed of the blades is changed by setting different powers for the motor 601, so that the water flow has different vortex ratios in front of the first straight pipe section 801, the vortex generation aggravates the disturbance of a flow field, and meanwhile, power is provided for the generation of cavitation vortex in the pipe.
After the water flow enters the venturi testing section 8, because the inner diameter of the first straight pipe section 801 is kept unchanged, the flow rate and the vorticity are kept unchanged, the water flow continues to flow into the contraction section 802, because the sectional area is rapidly reduced, the flow rate of the water flow is instantly increased, the pressure is reduced, and when the pressure is reduced to the saturated steam pressure of the water at the temperature, the water in the pipe enters a saturated state.
After water flow of the contraction section enters the throat section 803, cavitation with a weaker degree is generated at the front end of the throat section 803, the cavitation cloud further advances with the water flow, and cavitation clouds are generated from the upper side and the lower side of the edge wall of the throat part of the venturi tube without vortex and symmetrically develop downstream; in contrast, cavitation does not occur on the two side wall surfaces of the Venturi tube with the vortex, an obvious cavitation core occurs on the central line, the throat cavitation initial develops downstream along the central line under the influence of the vortex, and the cavitation thickness is diffused to the wall surfaces along the axis.
After water flows into the horn-shaped diffusion section 804, compared with a linear flat wall surface, the horn-shaped diffusion wall is used for enabling the cross section area of the flow distribution section to generate nonlinear change, the change of the flow area along the diffusion section is relatively slow, the slow pressure recovery is converted into higher speed amplitude, the length of the low-pressure area is prolonged, so that cavitation is further developed, the saturated water continues to be cavitated in the front half part of the diffusion section, and the cavitation degree is higher than that of the linear change of the section of the flow channel. Meanwhile, the addition of the vortex can inhibit the axial advance and retreat of the cavitation area in the linear flow, the length of the cavity is kept relatively fixed, and the influence of cavitation on the wall surface is reduced.
Compared with the conventional Venturi cavitation generator, the CFD numerical calculation method has the advantages that the turbine section 6 arranged in front of the Venturi straight pipe section is utilized to adjust the vorticity of water flow flowing through the Venturi testing section, the axial advance and retreat of the linear flow cavitation area are restrained, the length of a cavity is kept relatively fixed, and meanwhile, the cavitation area is moved to the center of the device by applying vortex, so that the cavitation phenomenon of the wall surface is reduced; the cross section area of the flow distribution section generates nonlinear change by utilizing the horn-shaped diffusion wall, the change of the flow area along the diffusion section is relatively slow, the slow pressure recovery is converted into higher speed amplitude, the length of the low-pressure area is prolonged, the volume fraction of steam is obviously increased, and further the cavitation efficiency is improved.
In the above CFD numerical calculation:
the inlet and outlet boundary conditions of the venturi are set to be a pressure inlet and a pressure outlet respectively, and the total pressure of the inlet is 5 x 10 5 Pa, and setting the peripheral speed formed by prerotation to 0.5m/s, and the static pressure at the outlet to be 1X 10 5 Pa. The wall surface of the Venturi is set to be a non-slip wall surface, and the turbulence intensity and the turbulence viscosity ratio of the inlet and outlet boundaries are 1% and 10% respectively. The turbulence model adopts an SST k-omega model, a pressure-velocity coupling mode adopts a SIMPLEC format, pressure equation dispersion adopts a PRESTO format, volume fraction space dispersion is a QUICK format, and momentum equation dispersion adopts a second-order windward format.
Claims (10)
1. The utility model provides a venturi cavitation test system which characterized in that: the device comprises an annular flow channel consisting of a water storage tank (1), a flow rate control pump (2), a turbine section (6) and a Venturi test section (8), wherein the turbine section (6) is arranged in the direction of the water inlet end of the Venturi test section (8);
the main body of the Venturi test section (8) is a Venturi tube and comprises a first straight tube section (801), a contraction section (802) connected to the output end of the first straight tube section (801), a throat tube section (803) connected to the tail end of the contraction section (802), a diffusion section (804) connected to one end of the throat tube section (803) and a second straight tube section (805) connected to one end of the diffusion section (804);
the inner wall of the diffusion section (804) is in a trumpet-shaped variable cross section.
2. The venturi cavitation test system of claim 1, wherein: and the annular flow passage is also provided with an electric control valve (3) and an electromagnetic flowmeter (5).
3. The venturi cavitation test system of claim 1, wherein: the turbine section (6) is provided with an insertion pipe section (602), the insertion pipe section (602) is provided with a rotating shaft (603) in an insertion mode, one end, located in the pipeline, of the rotating shaft (603) is provided with an impeller (604), and one end, located outside the pipeline, of the rotating shaft (603) is connected with the motor (601).
4. The venturi cavitation test system of claim 3, wherein: the impeller (604) is arranged close to the first straight pipe section (801) in the Venturi test section (8).
5. The venturi cavitation test system of claim 3, wherein: the flow rate control pump (2) and the motor (601) in the turbine section (6) are connected to the variable frequency control cabinet (4).
6. The venturi cavitation test system of claim 1, wherein: the pipelines at the two ends of the Venturi test section (8) are respectively provided with a first pressure gauge (7) and a second pressure gauge (9).
7. The venturi cavitation test system of claim 1, wherein: and a high-speed camera (10) is also arranged on one side of the Venturi test section (8).
8. The method of operating a venturi cavitation test system according to any of the claims 1 to 7, characterized in that it comprises the following steps:
1) opening the electric control valve (3) to any opening degree and starting the flow rate control pump (2), continuously adding water into the water storage tank (1), so that the system circulates under the non-cavitation condition and discharges the air remained in the system;
2) controlling the power and the lift of the flow rate control pump (2) through the variable frequency control cabinet (4), changing the opening degree of the electric control valve (3), gradually increasing the inlet pressure of the system from 0 KPa to 500 KPa, increasing the pressure to 25 KPa, and recording the corresponding flow of the electromagnetic flowmeter (5);
3) -monitoring the noise level associated with cavitation by visually observing the onset of cavitation in the venturi test section (8) until a visual indication of cavitation is observable by the high speed camera (10);
4) data acquisition is performed by a high-speed camera (10).
9. The method of operating a venturi cavitation test system as claimed in claim 8, wherein: in the process of the step 1), the dissolved oxygen in water is continuously measured at the position of the water storage tank (1) through the dissolved oxygen probe, so that the oxygen content in the water is ensured to be maintained at 8g/m 3 The subsequent operation is carried out after the equilibrium concentration of (A).
10. The method of operating a venturi cavitation test system as claimed in claim 8, wherein: the inlet pressure of the Venturi test section (8) is within the range of 0.3-0.5MPa, the outlet pressure is 0.1MPa, the convergence angle is 15 degrees, and the divergence angle is 6.2 degrees;
the pressure value is monitored by a first pressure gauge (7) and a second pressure gauge (9).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202210576226.0A CN115043458A (en) | 2022-05-25 | 2022-05-25 | Venturi cavitation test system and operation method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210576226.0A CN115043458A (en) | 2022-05-25 | 2022-05-25 | Venturi cavitation test system and operation method |
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| CN202210576226.0A Pending CN115043458A (en) | 2022-05-25 | 2022-05-25 | Venturi cavitation test system and operation method |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014003462A1 (en) * | 2012-06-29 | 2014-01-03 | 주식회사 신영이앤아이 | Method for removing nitrogen from wastewater |
| CN205538524U (en) * | 2016-02-03 | 2016-08-31 | 西华大学 | Testing equipment is used in abrasion test |
| CN108421756A (en) * | 2018-04-24 | 2018-08-21 | 浙江理工大学 | A kind of cavitation jet cleaning cavitation device |
-
2022
- 2022-05-25 CN CN202210576226.0A patent/CN115043458A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014003462A1 (en) * | 2012-06-29 | 2014-01-03 | 주식회사 신영이앤아이 | Method for removing nitrogen from wastewater |
| CN205538524U (en) * | 2016-02-03 | 2016-08-31 | 西华大学 | Testing equipment is used in abrasion test |
| CN108421756A (en) * | 2018-04-24 | 2018-08-21 | 浙江理工大学 | A kind of cavitation jet cleaning cavitation device |
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