CN-122015920-A - Nanometer bubble temperature, pressure and size measuring method based on laser extinction method

CN122015920ACN 122015920 ACN122015920 ACN 122015920ACN-122015920-A

Abstract

The application discloses a method for measuring temperature, pressure and size of a nanometer bubble based on a laser extinction method, relates to the technical field of measurement of photothermal properties of the nanometer bubble, and aims to solve the problem that the temperature, pressure and bubble size inside the bubble in the formation process of the nanometer bubble cannot be measured simultaneously by the existing method.

Inventors

JI YUKUN
REN YATAO
QI HONG

Assignees

哈尔滨工业大学

Dates

Publication Date: 20260512
Application Date: 20260212

Claims (10)

1. The measuring method is characterized by being realized based on a measuring device, wherein the measuring device comprises a pulse laser, a CCD camera, an objective lens and an avalanche photoelectric detector; The laser emitted by the pulse laser is focused by the objective lens and then irradiates into the aqueous solution containing the nano particles, the CCD camera is used for judging whether the laser irradiates onto the nano particles, and the avalanche photodetector is used for receiving transmission signals after the laser irradiates onto the nano particles; Step 1, turning on a pulse laser, fully preheating the pulse laser, and adjusting the output power of the pulse laser, namely the incident laser power, so that the nano particles can heat surrounding water and generate nano bubbles under the power; Step 2, imaging a laser spot in real time through a CCD camera, and adjusting the position of the laser spot at the same time to enable the laser spot to coincide with the nanoparticle, wherein when a bright point exists in an imaging diagram, laser irradiates the nanoparticle; step 3, turning on an avalanche photodetector, and obtaining transmission laser power after laser irradiates the nano particles by using the avalanche photodetector; step 4, subtracting the transmitted laser power from the incident laser power to obtain the laser power absorbed by the nano particles on the incident laser ; Step 5, obtaining the volume of the nano particles and utilizing the laser power Dividing the volume of the nano particles to obtain the volume heat source density of the nano particles ; Step 6, the volume heat source density of the nano particles Bringing into an energy equation to obtain the temperature of the nano particles And fluid temperature And according to the temperature of the nano-particles And fluid temperature And obtaining the fluid density and the fluid pressure in the process of forming the nano bubble by using a lattice Boltzmann method, and finally obtaining the size of the nano bubble by using the fluid density and the fluid pressure.
2. The method for measuring temperature, pressure and size of nano bubbles based on the laser extinction method according to claim 1, wherein the specific steps of the step 6 are as follows: Step 61, bulk Heat Source Density of nanoparticles Carrying out an energy equation, and solving by using a finite difference method to obtain the temperature of the nano particles And fluid temperature And utilizes the temperature of the nanoparticles And fluid temperature Constructing a temperature spatial distribution ; Step 62, obtaining fluid velocity and fluid density according to intermolecular acting force and a distribution function in the lattice Boltzmann method; Step 63, judging whether the maximum iteration number is reached, if the maximum iteration number is reached, executing step 64, and if the maximum iteration number is not reached, executing step 65; step 64, obtaining the size of the nano bubble according to the obtained fluid density; Step 65 based on temperature spatial distribution And using the P-R state equation to obtain the fluid pressure, and repeating steps 61 to 63 with the fluid pressure and the fluid velocity as the fluid pressure and the fluid velocity in the energy equation and the distribution function, respectively.
3. The method for measuring temperature, pressure and size of nano bubbles based on a laser extinction method according to claim 2, wherein the energy equation is expressed as: ; ; Wherein, the 、、 Respectively the density, the heat conductivity coefficient and the specific heat capacity of the fluid, For time, subscript Is noble metal material, subscript Is in the form of an aqueous solution, In the case of a fluid pressure, Is the fluid velocity.
4. A method for measuring temperature, pressure and size of nano bubbles based on laser extinction method according to claim 3, wherein the distribution function is expressed as: ; ; Wherein, the As a vector of the position of the object, For the time step size of the time step, Is a matrix of units which is a matrix of units, In the form of a discrete force item, As a source item, a source item is provided, In the form of a diagonal matrix of relaxation parameters, 、、、 Are all a function of the distribution, As a function of the distribution of the equilibrium state, Is a discrete velocity.
5. The method for measuring temperature, pressure and size of nanometer bubble based on laser extinction method according to claim 4, wherein the source term Expressed as: ; ; ; ; ; ; ; Wherein, the 、、、、、 Is that Is used for the control of the degree of freedom of the composition, Is the speed of sound of the lattice, And As the coefficient of the light-emitting diode, As the coefficient of intermolecular forces of force, As a function of the pseudo-potential, As the force between the molecules of the fluid, 、、 Respectively is Along with 、、 Components of the axis in three directions.
6. The method for measuring temperature, pressure and size of nanometer bubble based on laser extinction method according to claim 5, wherein the discrete force term Expressed as: ; Wherein, the 、、 Along the velocity of the fluid 、、 Components of the axis in three directions.
7. The method for measuring temperature, pressure and size of nanometer bubble based on laser extinction method according to claim 6, wherein acting force between molecules of fluid Expressed as: ; ; ; Wherein, the As the weight coefficient of the light-emitting diode, Is an intermediate variable.
8. The method for measuring temperature, pressure and size of nanometer bubble based on laser extinction method according to claim 7, wherein the fluid velocity Expressed as: ; ; Wherein, the As a distribution function.
9. The method for measuring temperature, pressure and size of nanometer bubble based on laser extinction method according to claim 8, wherein the fluid pressure is Expressed as: ; Wherein, the Is a gas constant which is a general purpose gas constant, And Is constant.
10. The method for measuring temperature, pressure and size of nano bubbles based on a laser extinction method according to claim 1, wherein the nano particles are noble metal materials.

Description

Nanometer bubble temperature, pressure and size measuring method based on laser extinction method Technical Field The application relates to the technical field of nanometer bubble photo-thermal property measurement, in particular to a method for measuring temperature, pressure and size of nanometer bubbles based on a laser extinction method. Background The plasmon nanometer vapor bubble is formed by photo-thermal phenomenon generated by exciting the plasmon material by resonance wavelength laser. By virtue of the unique photo-thermal and optical characteristics, the plasmon nanometer bubble is widely studied in the fields of micro-processing, micro-manipulation, robot propulsion, molecular enrichment and sensing, clinical treatment, solar steam generation and the like. Based on the application prospect, the related scholars develop the deep system exploration on the formation mechanism of the plasmon nanometer vapor bubble. Early in order to capture bubble growth dynamics, researchers developed various experimental methods such as dark field imaging, hydrophone detection, transparency detection, and the like. However, the nucleation and growth process of the bubbles involves severe morphological changes, molecular-nanoscale phenomena (such as surface chemistry, curvature, wetting conditions, and surface tension), and other factors (such as pulse duration, nanostructure size, laser intensity, and interfacial thermal resistance), which results in extremely complex growth mechanisms of the nanobubbles. In addition, since nucleation of nano bubbles occurs and growth thereof occurs at a nano scale, the existing technology cannot measure the temperature, pressure and bubble size inside the bubbles in the nano bubble formation process at the same time. Disclosure of Invention The invention aims to provide a method for measuring the temperature, pressure and size of a nanometer bubble based on a laser extinction method, aiming at the problem that the prior method can not measure the temperature, pressure and bubble size in the bubble in the nanometer bubble forming process. The technical scheme adopted by the invention for solving the technical problems is as follows: The measuring method is realized based on a measuring device, and the measuring device comprises a pulse laser, a CCD camera, an objective lens and an avalanche photoelectric detector; The laser emitted by the pulse laser is focused by the objective lens and then irradiates into the aqueous solution containing the nano particles, the CCD camera is used for judging whether the laser irradiates onto the nano particles, and the avalanche photodetector is used for receiving transmission signals after the laser irradiates onto the nano particles; Step 1, turning on a pulse laser, fully preheating the pulse laser, and adjusting the output power of the pulse laser, namely the incident laser power, so that the nano particles can heat surrounding water and generate nano bubbles under the power; Step 2, imaging a laser spot in real time through a CCD camera, and adjusting the position of the laser spot at the same time to enable the laser spot to coincide with the nanoparticle, wherein when a bright point exists in an imaging diagram, laser irradiates the nanoparticle; step 3, turning on an avalanche photodetector, and obtaining transmission laser power after laser irradiates the nano particles by using the avalanche photodetector; step 4, subtracting the transmitted laser power from the incident laser power to obtain the laser power absorbed by the nano particles on the incident laser ; Step 5, obtaining the volume of the nano particles and utilizing the laser powerDividing the volume of the nano particles to obtain the volume heat source density of the nano particles; Step 6, the volume heat source density of the nano particlesBringing into an energy equation to obtain the temperature of the nano particlesAnd fluid temperatureAnd according to the temperature of the nano-particlesAnd fluid temperatureAnd obtaining the fluid density and the fluid pressure in the process of forming the nano bubble by using a lattice Boltzmann method, and finally obtaining the size of the nano bubble by using the fluid density and the fluid pressure. Further, the specific steps of the step 6 are as follows: Step 61, bulk Heat Source Density of nanoparticles Carrying out an energy equation, and solving by using a finite difference method to obtain the temperature of the nano particlesAnd fluid temperatureAnd utilizes the temperature of the nanoparticlesAnd fluid temperatureConstructing a temperature spatial distribution; Step 62, obtaining fluid velocity and fluid density according to intermolecular acting force and a distribution function in the lattice Boltzmann method; Step 63, judging whether the maximum iteration number is reached, if the maximum iteration number is reached, executing step 64, and if the maximum iteration number is not reached, executing step 65; step 64, ob