CN111707664A

CN111707664A - Observation experiment device suitable for super hydrophobic surface

Info

Publication number: CN111707664A
Application number: CN202010426094.4A
Authority: CN
Inventors: 郑腾飞; 李园; 王朝晖
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2020-09-25

Abstract

The invention relates to an observation experiment device suitable for a super-hydrophobic surface, which comprises 3 parts, namely a flow channel device, an observation device and a test surface, which are matched with each other; the flow channel is made of transparent PDMS, and the open end of the flow channel is provided with deionized water through a connected injection pump, and the deionized water enters the test area at a stable flow rate after passing through the longer rectifying area. The top end of the flow passage of the test area is provided with a pressure hole, and the pressure meter connected with the pressure hole is matched with a pressure valve at the other end of the flow passage to monitor and control the pressure of the fluid in real time. The test area is configured with a light source and a high speed camera at both ends to capture fluid flow and air layer changes occurring on the test surface. The preparation technology of the test surface and the flow channel is mature, and multiple sets of the test surface and the flow channel can be prepared according to different parameters. The test experimental device can study the influence of different pressure gradients and surface structure parameters on the stability of the super-hydrophobic surface gas layer and the resistance reduction efficiency through experiments.

Description

Observation experiment device suitable for super hydrophobic surface

Technical Field

The invention belongs to the technical field of micro-nano manufacturing, and particularly relates to an observation experiment device suitable for a super-hydrophobic surface.

Background

By applying the micro-nano manufacturing technology, devices such as a sensor and the like are integrated in a micro volume, and the miniaturization and low cost of an experimental system can be realized. Particularly, the experimental device of the fluid system adopts a test system formed by a micro-nano manufacturing technology, and is more beneficial to realizing the automation and the miniaturization of an instrument.

The air layer in the microstructure of the submerged superhydrophobic (SHPo) surface enables the liquid to slide over the surface, thereby reducing drag. However, the instability of the air layer retained by the surface prevents the practical use of such a surface. Therefore, the influence of various influencing factors on the instability of the gas layer needs to be researched. However, most previous studies only considered that the structured superhydrophobic surface is affected by air diffusion, condensation, etc. under conditions where the pressure is nearly uniform. In fact, the superhydrophobic surface inevitably bears uneven pressure conditions in application, and the design of the surface structure is also a main factor influencing the practical application effect, so that the current research and observation experiments are insufficient.

Disclosure of Invention

The invention aims to provide an observation experiment device suitable for a super-hydrophobic surface so as to solve the problems.

In order to achieve the purpose, the invention adopts the following technical scheme:

an observation experiment device suitable for a super-hydrophobic surface comprises a flow channel device, an observation device and a surface to be detected; the observation device is arranged on the side surface of the flow channel device, and the surface to be measured is arranged at the bottom of the flow channel device; the flow passage device comprises a long straight flow passage, an injection pump, a control valve and a pressure hole; the long straight runner is not provided with a lower surface, the surface to be measured is arranged on the lower surface of the long straight runner, the two ends of the long straight runner are respectively provided with a runner water inlet and a runner water outlet, the injection pump is arranged at the runner water inlet, and the control valve is arranged at the runner water outlet; the long straight flow channel is divided into a rectifying area and a testing area, a plurality of pressure holes are formed in the top of the flow channel of the testing area, pressure taps are arranged on the pressure holes, and a pressure gauge and a pressure difference gauge are connected to the pressure taps; the observation device comprises a transmitter and a receiver, and the transmitter and the receiver are respectively arranged on two sides of the test area.

Furthermore, the long straight flow channel is square, and the caliber size is 1mm x 1 mm; the material used for the long straight flow channel and the surface to be measured is polydimethylsiloxane.

Furthermore, the surface to be tested is provided with a ridge structure with the width of 200 mu m, the surface to be tested is separated into two subareas, the length of the rectifying area of the long straight flow channel is 13cm, and the length of the testing area of the long straight flow channel is 8 cm.

Further, the transmitter includes a laser light source and a light diffuser; the laser light source is provided with a light diffuser.

Further, the receiver includes a high-speed camera and a 10x objective lens; the 10x objective lens is set on the high-speed camera.

Furthermore, the surface to be measured is gullies with different widths; the gas fraction of the surface to be measured is selected to be 50%, and the depth of a gully structure is 50 μm.

Furthermore, the number of the pressure holes is three, the pressure difference meter is connected to the pressure tap heads of the two sections of the test area, and the pressure meter is connected to the pressure tap head in the middle of the test area.

Compared with the prior art, the invention has the following technical effects:

the test experiment device can supply deionized water into the flow channel by using the injection pump at one end of the flow channel, and the water pressure value is adjusted by using the pressure valve connected at the other end of the flow channel. The rectifying area is set to be long enough, so that the experimental flow conditions for testing are ensured to be stable as much as possible. The pressure difference meter connected to the pressure taps at the two ends of the test area and the pressure meter connected to the pressure tap at the middle part of the test area can test the water pressure and the pressure drop in real time. The observation device is provided with an optical diffuser and a high-power objective lens, so that a high-speed camera can capture the dynamic motion of the gas layer positioned in the groove. The observation device is used for observing and recording the condition of the test surface, so that the measurement and research of the influence effect of the water pressure gradient on the SHPo surface stability and the drag reduction effect are realized.

The main body flow channels of the testing experimental device are all made of PDMS, the flow channel mould is made of 3D printing technology, and the testing surface mould is made of photoetching technology. Both of the two technologies are mature, and the die and the device can be manufactured in multiple sets. The structural parameters of the manufactured surface to be measured can be set by self, a plurality of groups of different structural intervals can be made to serve as the parameters to be measured, and the influence mechanism of the structural parameters can be explored through observation experiments. In the experiment, the flow channel made of the transparent material is also beneficial to observing the surface condition of the SHPo in real time. Is beneficial to real-time regulation and control of pressure and experimental observation.

Drawings

FIG. 1 is a schematic diagram of an experimental setup;

FIG. 2 is a side view of a test zone;

FIG. 3 is a cross-sectional view of a test zone;

fig. 4 is a schematic structural design diagram of a surface to be measured.

Wherein: 1 is a long straight flow channel; 2 is an injection pump; 3 is a water inlet of the runner; 4 is a runner water outlet; 5 is a pressure valve; 6 is a pressure hole; 7 is a laser light source; 8 is a light diffuser; 9 is a high-speed camera; 10 is a 10x objective lens; and 11 is a test surface.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

the invention is suitable for an observation experiment device of a super-hydrophobic surface, and consists of 3 parts, namely a flow channel device, an observation device and a test surface which are matched with each other.

See fig. 1. The long straight flow passage 1 is a square long straight flow passage. The left end of the flow channel is open and is a flow channel water inlet 3, and the injection pump 2 is connected to the flow channel water inlet 3. The right end of the flow channel is closed, a small hole is opened to form a flow channel water outlet 4, and a pressure valve 5 is arranged on the water outflow pipe. The flow channel is divided into two parts, a first pressure hole 6 is used as a boundary, a rectifying area is arranged from the water inlet to the pressure hole, and a testing area is arranged behind the pressure hole. A laser light source 7 is arranged on one side of the test area, and a light diffuser 8 is arranged in front of the light source. The other side of the test area is provided with a high speed camera 9, the high speed camera 9 is provided with a 10x objective lens 10, and a test surface 11 is fitted with the runner 1 as the lower bottom surface of the runner 1.

In the preferred embodiment of the present invention. The mold of the runner 1 is made of photosensitive resin using a 3D printer. After a mould is made, a main agent SYLGUARD-184A and a hardening agent SYLGUARD-184B are mixed according to the mass ratio of 10: 1 proportion, floating bubbles in the mixed solution to the surface and breaking the bubbles by using a vacuumizing mode, pouring the solution on a mould, and then putting the mould into a 120-degree oven for curing for one hour, wherein one side of the runner is kept in an open state during curing.

See fig. 2. The top of the flow passage of the test area is provided with 3 pressure holes 6, and each pressure hole is provided with a matched pressure tap. The pressure holes are respectively positioned at the two ends and the middle of the test area. The pressure tap in the middle is connected with a pressure gauge (12). The pressure taps at the two ends are respectively connected with two probes of a pressure difference meter (13). At the bottom of the test zone flow channel is a test surface 11.

See fig. 3. The bottom of the flow channel in the test area is a test surface 11, and the test surface 11 is a SHPo surface with an array of trenches.

See fig. 4. The main structure of the test surface 11 is an array of trenches, the array pattern being divided into two pattern areas by a ridge structure. The ridge structure is located in the middle of the test zone.

In the preferred embodiment of the present invention. The mold for testing the surface 11 is made by applying a photolithographic process to a silicon wafer. The pattern of the test surface 11 is designed as an array of grids. The width of the pattern area is equal to the width of the flow channel 1, and the length is equal to the length of the test area of the flow channel 1. The trenches of the array are separated into two regions by a ridge structure of width 200 μm. In photolithography, the depth of the trenches is fixed at 50 μm and the gas fraction is fixed at 50%, where the gas fraction actually characterizes the pitch of the trench structures, and 50% means that the pitch of the trench structures is equal to the width of the trenches. The test surface 11 was also prepared by applying the same PDMS solution to a silicon wafer after evacuation and curing in a 120 degree oven for one hour. The prepared SHPo surface was bonded to a square channel with one side open by using oxygen plasma treatment. After the bonding is completed, the surface of the array groove is embedded with the test region of the flow channel 1, and the position is shown in fig. 2 and fig. 3. The two regions separated by the ridge structure are located between 3 pressure holes, respectively.

Claims

1. An observation experiment device suitable for a super-hydrophobic surface is characterized by comprising a flow channel device, an observation device and a surface to be detected; the observation device is arranged on the side surface of the flow channel device, and the surface to be measured is arranged at the bottom of the flow channel device; the flow channel device comprises a long straight flow channel (1), an injection pump (2), a control valve (5) and a pressure hole (6); the long straight runner (1) is not provided with a lower surface, the surface to be measured is arranged on the lower surface of the long straight runner (1), the two ends of the long straight runner (1) are respectively provided with a runner water inlet (3) and a runner water outlet (4), the injection pump (2) is arranged at the runner water inlet, and the control valve (5) is arranged at the runner water outlet (4); the long straight flow channel (1) is divided into a rectifying area and a testing area, a plurality of pressure holes (6) are arranged at the top of the flow channel of the testing area, pressure taps are arranged on the pressure holes, and a pressure gauge and a pressure difference gauge are connected to the pressure taps; the observation device comprises a transmitter and a receiver, and the transmitter and the receiver are respectively arranged on two sides of the test area.

2. An observation experiment device suitable for a superhydrophobic surface according to claim 1, wherein the long straight flow channel (1) is square, and the caliber size is 1mm x 1 mm; the material used by the long straight flow channel (1) and the surface to be measured (11) is polydimethylsiloxane.

3. An observation experiment device suitable for a super-hydrophobic surface, according to claim 1, characterized in that the surface to be measured (11) has a ridge structure with a width of 200 μm, which separates the surface to be measured into two sub-regions, the length of the rectifying region of the long straight flow channel (1) is 13cm, and the length of the testing region of the long straight flow channel (1) is 8 cm.

4. Observation experiment device suitable for a superhydrophobic surface according to claim 1, characterized in that the emitter comprises a laser light source (7) and a light diffuser (8); the laser light source (7) is provided with a light diffuser (8).

5. Observation experiment device suitable for a superhydrophobic surface according to claim 1, characterized in that the receiver comprises a high speed camera (9) and a 10x objective (10); a10 x objective lens (10) is disposed on the high speed camera (9).

6. An observation experiment device suitable for a super-hydrophobic surface according to claim 1, characterized in that the surface to be measured (11) is a ravine with different widths; the gas fraction of the surface (11) to be measured is 50% and the depth of the gully structure is 50 μm.

7. An observation experiment device suitable for a superhydrophobic surface according to claim 1, wherein the number of the pressure holes is three, the pressure difference gauge is connected to the pressure taps of the two sections of the test area, and the pressure gauge is connected to the pressure tap in the middle of the test area.