CN106600623A - Blasting-type cooling system flow field visualization method based on zinc sulfide - Google Patents

Abstract

The invention discloses a zinc sulfide-based blasting cooling system flow field visualization method, which is to add zinc sulfide powder in the blast air flow, and irradiate the air flow with an excitation light source, and the zinc sulfide particles are excited to release blue-purple fluorescence At the same time, the CCD camera absorbs the fluorescence for a long time exposure to form an image with many light tracks, so as to realize the visualization of the air flow field. The components mainly involved in the present invention mainly include an air blast injection system, an air cooling and conveying system, and a CCD (Charge-coupled Device) image acquisition system. The invention is applied to the visualization analysis of the air flow field of the blower cooling technology. The device used in the invention has simple structure and low use cost, and is very suitable for application and popularization.

Description

A Zinc Sulfide-Based Flow Field Visualization Method for Blast Cooling System

technical field

The invention belongs to the field of airflow flow field visualization, in particular to a method for visualization of airflow organization based on zinc sulfide fluorescence reaction, in particular to a visualization method for flow field analysis of jet airflow applied in a blast cooling system.

Background technique

Blast cooling technology is a technology that uses low-temperature, high-speed air to cool objects. When the high-speed flowing low-temperature airflow hits the object to be cooled, the air boundary layer on the surface of the object is thinned, the convective heat transfer is strengthened, and the cooling rate is increased. The air jet flow field of the blast cooling device is a key factor determining the heat exchange efficiency and energy consumption of the device. For cooling objects of different shapes and sizes, it is often necessary to design and adjust the air flow field, such as using different injection forms (orifice type, nozzle type, etc.) and various structural parameters (orifice nozzle size and opening ratio, nozzle size Wait). The air flow field of the injection system is not intuitive, and the premise of designing a reasonable air flow field is the visualization of the air flow field, which is also a key issue in the development and design of the blast cooling device. At present, the commonly used flow field visualization methods include helium bubble display technology, speckle velocimetry technology and particle image velocimetry technology (PIV), etc., but these technologies are not yet available in China, and basically need to be imported from abroad, and the cost of use is very high. It ranges from 100,000 to millions, which is unbearable for small and medium-sized enterprises and ordinary scientific research institutions.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art. The present invention provides a method for visualizing the air flow field based on the fluorescence reaction of zinc sulfide, which is a method for recording the fluorescence trajectory of zinc sulfide by using CCD for a long time exposure, so as to directly reflect the wind blast. Method for jetting air flow field of type cooling device.

Technical scheme of the present invention is:

The device used in a zinc sulfide-based blast cooling system flow field visualization method includes an air cooling and delivery system, an air blast injection system and a CCD image acquisition system; the air cooling and delivery system consists of an air cooler, an air supply pipe, Composed of zinc sulfide powder adding device, return air pipe, and high-efficiency filter; air blast injection system consists of static pressure box, air supply orifice plate, injection cooling area and mesh belt; CCD image acquisition system includes two parts: CCD camera and light source ; The steps of this method are:

(1) Turn on the light source;

(2) Zinc sulfide powder with a particle size of 5 μm-20 μm is added to the zinc sulfide powder adding device;

(3) Start the CCD camera.

The particle size of the zinc sulfide powder was 10 μm.

The luminescent light source emits light with a wavelength of 340nm-480nm. The powder is excited by light with a wavelength of 340nm-480nm, and a fluorescence reaction occurs, and the fluorescence is recorded by a CCD camera to form a light track; this track can directly reflect the streamline and flow field distribution of the blast cooling equipment.

The luminescent light source emits light with a wavelength of 400nm. The excitation light wavelength of zinc sulfide fluorescence reaction is 400nm. According to the optical properties of zinc sulfide, under the excitation of light at this wavelength, zinc sulfide undergoes a fluorescence reaction, releasing visible photoluminescence, which is recorded by a CCD camera.

When shooting the flow field, the CCD camera uses the processing method of small aperture and long exposure time. Using digital photos with small aperture and long exposure time to reflect the air flow field method. Each zinc sulfide particle follows the airflow and will move a certain distance during the exposure time, and this process will leave a clear light trail on the CCD. This trajectory can reflect the movement trajectory of the zinc sulfide particles, that is, the streamline of the air flow, and multiple light trajectories can reflect the overall movement of the air flow, that is, the streamline and flow field distribution.

The static pressure box ensures the uniformity of the air flow ejection outlet. The nozzle size and opening ratio of the orifice determine the flow velocity and flow rate of the jet airflow and the flow field in the jet cooling area.

CCD is the abbreviation of charge coupled device (charge coupled device). It can convert light into electric charge and store and transfer the electric charge. It can also take out the stored charge and change the voltage. Therefore, it is an ideal CCD camera component. Advanced CCD cameras are widely used due to their small size, light weight, unaffected by magnetic fields, and anti-vibration and impact characteristics.

A zinc sulfide adding device is installed on the air supply pipe. The zinc sulfide is powdery and the particle size is 10 μm, so that the zinc sulfide powder is not easy to settle in the air, but is evenly distributed in the air. The amount of zinc sulfide powder added can be adjusted, so as to adjust the density of the fluorescent track during the flow field visualization image acquisition process. A high-efficiency filter is installed on the return air duct, the purpose of which is to filter the air and collect zinc sulfide particles, to prevent zinc sulfide particles from entering the air cooler, and to avoid excessive zinc sulfide particles in the air flow from interfering with visualization.

The CCD image acquisition system includes two parts: a light source and a CCD camera. The wavelength of light emitted by the light source is 340nm-480nm, and the fluorescence reaction of zinc sulfide is the strongest under the light irradiation of this wavelength band. The CCD camera has the functions of small aperture and long exposure time, which is conducive to clearly recording the movement track of zinc sulfide particles. The zinc sulfide particles have a fluorescent reaction under the irradiation of the light source, and the particles follow the airflow in the spray cooling area. The particles will move a certain distance during the exposure time of the CCD camera. The longer the exposure time, the longer the moving distance of the particles. CCD The longer a light trail is left on it. Each light trace reflects an airflow streamline, and multiple light traces can reflect the streamline and flow field distribution of airflow.

The side facing the CCD acquisition system of the air jet cooling area is made of transparent material, which can pass the light of the light source 11 and the fluorescence emitted by zinc sulfide.

The invention uses the fluorescent reaction of zinc sulfide to reflect the flow of air, and records the movement track of zinc sulfide particles through a CCD camera with a small aperture and long shutter, and then reflects the streamline and flow field distribution of the jet airflow, which is an innovative method The air flow field visualization method has a simple structure and low cost, and can be realized with a little modification in the air injection system, which greatly reduces the cost of realizing the air flow field visualization.

Description of drawings

FIG. 1 is a schematic diagram of a flow field visualization device applying the blast cooling system of the present invention.

1. Air cooler 2. Air supply pipe 3. Zinc sulfide powder adding device 4. Static pressure box 5. Air supply orifice plate 6. Air jet cooling area 7. Mesh belt 8. Return air pipe 9. High efficiency filter 10. CCD camera 11. Luminous light source.

detailed description

In order to make the operation process and creative features realized by the present invention easy to understand, the present invention will be further described below in conjunction with specific embodiments.

The visualization device of the air flow field applying the air blast cooling system of the present invention can be divided into three parts: air cooling and delivery system, air blast injection system and CCD image acquisition system; air cooling and delivery system consists of air cooler 1 , air supply pipe 2, zinc sulfide powder adding device 3, return air pipe 8, and high-efficiency filter 9; the air blast injection system is composed of static pressure box 4, air supply orifice plate 5, spray cooling area 6 and mesh belt 7 ; The CCD image acquisition system includes a CCD camera 10 and a light source 11 in two parts.

The air is cooled in the air cooler 1 and fed into the air duct 2 . The zinc sulfide powder of appropriate proportion is added in the air of air duct 2 by zinc sulfide powder adding device 3 . The cold air mixed with zinc sulfide powder is conveyed in the plenum 4. The bottom of the plenum 4 is provided with an air supply orifice plate 5 with a certain opening ratio, and the cold air mixed with zinc sulfide powder sprays airflow from the nozzle on the orifice plate 5, and the airflow impacts the object to be cooled in the cooling area 6 . A mesh belt 7 is arranged in the cooling area, and objects to be cooled are placed on the mesh belt 7 . The airflow passing through the object to be cooled and the mesh belt 7 returns to the return air duct 8 from the bottom of the cooling area 5 . The air return pipe 8 is provided with a high-efficiency filter 9 for collecting zinc sulfide powder to prevent the zinc sulfide powder from entering the air cooler 1 .

The front side of the air jet cooling area 6 (facing the CCD acquisition system) is made of transparent materials, which can pass the light from the light source 11 and the fluorescence emitted by zinc sulfide. Zinc sulfide is irradiated by light with a wavelength of 400nm from the light source 11 in the air injection area, which excites the fluorescence reaction of zinc sulfide and emits blue-purple visible light, which is captured by the CCD camera 10 . The CCD camera 10 adopts the mode of a small aperture to continuously expose for a period of time. During this time, each zinc sulfide particle moves through a certain distance in the air. The light traces can reflect the streamline and flow field distribution of (6) injected air in the air injection area.

This method uses the fluorescence reaction of zinc sulfide to reflect the flow of air, which is an innovative method for visualizing the air flow field, and this method has a simple structure and low cost, and is very suitable for popularization and application.

Claims (6)

1. a kind of forced draft cooling system flow field visualization method based on zinc sulfide, it is characterised in that：The dress that this method is used Put including air cooling and induction system, air blast spraying system and ccd image acquisition system；Air is cooled down and induction system By air cooler（1）, ajutage（2）, zinc sulfide powder adding set（3）, backwind tube（8）, high efficiency particulate air filter（9）Composition； Air blast spraying system is by plenum chamber（4）, air-supply orifice plate（5）, spray cooling region（6）And guipure（7）Composition；Ccd image Acquisition system includes CCD camera（10）And illuminating source（11）Two parts；The step of this method is realized be：

（1）Open illuminating source（11）；

（2）Zinc sulfide powder adding set（3）The middle zinc sulfide powder for adding particle diameter at 5 μm -20 μm；

（3）Start CCD camera（10）.

2. a kind of forced draft cooling system flow field visualization method based on zinc sulfide according to claim 1, its feature It is：The particle diameter of zinc sulfide powder is 10 μm.

3. a kind of forced draft cooling system flow field visualization method based on zinc sulfide according to claim 1, its feature It is：Illuminating source（11）Launch the light that wavelength is 340nm-480nm.

4. a kind of forced draft cooling system flow field visualization method based on zinc sulfide according to claim 1, its feature It is：Illuminating source（11）Launch the light that wavelength is 400nm.

5. a kind of forced draft cooling system flow field visualization method based on zinc sulfide according to claim 1, its feature It is：When shooting flow field, CCD camera（10）Using the processing method of the long time of exposure of little aperture.

6. a kind of forced draft cooling system flow field visualization method based on zinc sulfide according to claim 1, its feature It is：Air spray cooling region（6）The one side towards CCD acquisition systems be made up of transparent material.