CN-121809341-B - Cavitation turbulence numerical simulation method and system based on gas-liquid sliding speed correction

CN121809341BCN 121809341 BCN121809341 BCN 121809341BCN-121809341-B

Abstract

The invention provides a cavitation turbulence numerical simulation method and a system based on gas-liquid sliding speed correction, which relate to the technical field of cavitation numerical simulation and are characterized in that a density gradient field of a gas-liquid two-phase interface area is established by acquiring gas phase volume fraction distribution and liquid phase speed field distribution in a fluid pipeline, and constructing a gas-liquid interface dynamic characteristic function which comprises an interface curvature item and a local vortex item and is expressed by coupling, correcting the gas-liquid phase velocity by adopting a self-adaptive gas-liquid sliding velocity correction model, and solving turbulence characteristic parameters and pressure field distribution in the cavitation flow field. Therefore, the accuracy and the refinement degree of gas-liquid interface dynamics description can be remarkably improved, the adaptability of the sliding speed correction model to interface nonlinear characteristics is enhanced, and the cavitation turbulence behavior can be more accurately simulated, so that the accuracy and the reliability of cavitation turbulence numerical simulation are improved, and more scientific and effective technical support is provided for cavitation prediction and control in the field of complex engineering.

Inventors

GE MINGMING
CAI XIAOFENG
LIN YINA
JIANG YI
LIU HAINA

Assignees

北师香港浸会大学

Dates

Publication Date: 20260505
Application Date: 20260304

Claims (8)

1. The cavitation turbulence numerical simulation method based on gas-liquid sliding speed correction is characterized by comprising the following steps of: acquiring gas phase volume fraction distribution and liquid phase velocity field distribution in a fluid pipeline, and establishing a density gradient field of a gas-liquid two-phase interface region based on the gas phase volume fraction distribution; Constructing a gas-liquid interface dynamic characteristic function by using the density gradient field and the liquid phase velocity field distribution, wherein the dynamic characteristic function comprises a coupling expression of an interface curvature item and a local vortex item; Based on the numerical distribution of the dynamic characteristic function, correcting the gas-liquid phase velocity by adopting a self-adaptive gas-liquid sliding velocity correction model; Substituting the corrected gas-liquid phase velocity into a turbulent strain rate transport equation, and solving turbulent characteristic parameters and pressure field distribution in a cavitation flow field; Constructing the gas-liquid interface the dynamic feature function includes: obtaining a density Laplacian operator through the divergence operation of a density gradient field, and then constructing an average curvature expression by combining the direction information of the density gradient; the vorticity vector is obtained by adopting the rotation operation of the speed field; Projecting the average curvature and the vector of the vortex quantity to the density gradient direction to obtain the normal curvature and the normal vector component of the interface; Constructing a gas-liquid interface dynamic characteristic function based on the normal curvature and the normal vortex vector component; obtaining a principal curvature on an interface tangential plane by calculating a Laplacian operator and a normal vector of a density gradient field, and finally obtaining the average curvature expression with grid independence; The vortex vector is obtained by calculating the speed gradient of the liquid phase speed field in all directions, further solving the rotation of the speed field to obtain the vortex vector, and obtaining the stable characteristic vortex by adopting a time average method.
2. The cavitation turbulence numerical simulation method based on gas-liquid slip velocity correction according to claim 1, wherein a density gradient field of the gas-liquid two-phase interface area is established, a gas phase volume fraction distribution function is established by utilizing acoustic emission detection to identify bubble characteristics, and then gas-liquid two-phase mixed density is calculated; and calculating the spatial change rate of the mixed density by adopting a central differential format, identifying an interface region by combining the modulus value and the direction vector of the density gradient and the characteristic value of the second derivative tensor, and finally constructing a density gradient field representing the strength and the direction of the interface.
3. The cavitation turbulence numerical simulation method based on gas-liquid slip velocity correction according to claim 2, wherein the gas-liquid two-phase mixed density is calculated, the phase distribution of calculation points is determined based on the gas phase volume fraction, the weighted calculation is adopted for the two-phase region, the correction of the pressure to the gas phase density is utilized, and the mixed density is obtained through the weighted contribution value of the gas-liquid two phases.
4. A cavitation turbulence numerical simulation method based on gas-liquid slip velocity correction according to claim 3, wherein the gas-liquid phase velocity is corrected by performing coupling operation with a pressure gradient and a vortex flow field respectively through a dynamic characteristic function, and calculating correction coefficients of a rising velocity and a lateral drift velocity of bubble motion respectively in combination with a direction modulation factor, and correcting the gas-liquid phase velocity by using the correction coefficients.
5. The cavitation turbulence numerical simulation method based on gas-liquid slip velocity correction according to claim 4, wherein the turbulence strain rate transport equation is as follows: ; Wherein, the As a tensor of the strain rate of the turbulent flow, In order to be able to take time, As a component of the average velocity, In order to achieve a fluid density, In the case of a pressure force, the pressure, In order to achieve a kinematic viscosity, A term is generated for the relative motion turbulence, As an interface stress term, the interface stress term, For the purpose of the additional turbulence dissipation term, Representing the partial derivative operator to the direction of the spatial coordinate k, Representing the partial derivative operator to the direction of the spatial coordinates i, Representing the partial derivative operator to the direction of the spatial coordinate j, Is a laplace operator.
6. Cavitation turbulence numerical simulation system based on gas-liquid slip velocity correction, applied to the method according to any one of claims 1 to 5, comprising: The data acquisition and differentiation module is used for acquiring gas phase volume fraction distribution and liquid phase velocity field distribution in the fluid pipeline and establishing a density gradient field of a gas-liquid two-phase interface area based on the gas phase volume fraction distribution; the dynamic characteristic function construction module is used for constructing a gas-liquid interface dynamic characteristic function by utilizing the density gradient field and the liquid phase velocity field distribution, and the dynamic characteristic function comprises a coupling expression of an interface curvature item and a local vortex item; The correction module is used for correcting the gas-liquid phase velocity by adopting a self-adaptive gas-liquid sliding velocity correction model based on the numerical distribution of the dynamic characteristic function; And the parameter solving module is used for substituting the corrected gas-liquid phase velocity into a turbulent strain rate transport equation to solve turbulent characteristic parameters and pressure field distribution in the cavitation flow field.
7. The computer equipment comprises a memory and a processor, wherein the memory stores a computer program, and the computer program is characterized in that the processor realizes the steps of the cavitation turbulence numerical simulation method based on gas-liquid sliding speed correction according to any one of claims 1-5 when executing the computer program.
8. A computer readable storage medium, on which a computer program is stored, is characterized in that the computer program, when executed by a processor, implements the cavitation turbulence numerical simulation method steps based on gas-liquid slip velocity correction as set forth in any one of claims 1 to 5.

Description

Cavitation turbulence numerical simulation method and system based on gas-liquid sliding speed correction Technical Field The invention relates to the technical field of cavitation numerical simulation, in particular to a cavitation turbulence numerical simulation method and system based on gas-liquid sliding speed correction. Background Cavitation is an important research object in the field of fluid mechanics, and has wide application value in high-speed flow, liquid transportation, ocean engineering and other scenes. Cavitation generally occurs when the local pressure of a liquid falls below its saturated vapor pressure, the liquid begins to vaporize to form bubbles, and the bubbles collapse as the pressure rises back. The cavitation phenomenon has extremely strong nonlinearity and multiscale characteristics due to complex phase transition, turbulence and gas-liquid interface dynamic behaviors in the process. In recent years, with the development of numerical simulation technology, cavitation turbulence numerical simulation has become an important means for researching cavitation mechanism. Traditional cavitation models are mostly based on Reynolds Average (RANS) or large vortex simulation (LES), and describe the dynamic behavior of gas-liquid two-phase flow by combining volume fraction (VOF) or Euler-Lagrange method. However, these methods often rely on empirical models when dealing with dynamic characteristics and slip velocity correction of gas-liquid interfaces, and cannot fully reflect interface nonlinear characteristics and interphase coupling effects in cavitation. The prior art has a great deal of shortfalls in spite of significant progress in the cavitation turbulence numerical simulation field. Firstly, the traditional gas-liquid interface dynamic modeling method has rough coupling description on the geometrical characteristics of an interface and the local vorticity of fluid, is difficult to accurately capture the influence of interface curvature change on the cavitation behavior, secondly, the traditional gas-liquid sliding speed model usually adopts a fixed empirical formula, the local dynamic characteristics and turbulence characteristic parameters of the gas-liquid interface cannot be fully considered, so that the accuracy and the robustness of a numerical simulation result are required to be improved, in addition, in the solving process of a turbulence strain rate transport equation in a cavitation flow field, the traditional method has simplified processing on the relative speed of the gas-liquid phase, and the feedback effect of the interface nonlinear coupling effect on the turbulence characteristic is ignored, so that the accuracy of the turbulence characteristic parameter prediction is limited. The problems not only affect the reliability of cavitation turbulence numerical simulation, but also provide serious challenges for cavitation behavior prediction and control in the practical application of complex engineering. Disclosure of Invention The present invention has been made to solve the above-mentioned technical problems. The invention provides a cavitation turbulence numerical simulation method and system based on gas-liquid sliding speed correction. According to one aspect of the present invention, there is provided a cavitation turbulence numerical simulation method based on gas-liquid slip velocity correction, comprising: acquiring gas phase volume fraction distribution and liquid phase velocity field distribution in a fluid pipeline, and establishing a density gradient field of a gas-liquid two-phase interface region based on the gas phase volume fraction distribution; Constructing a gas-liquid interface dynamic characteristic function by using the density gradient field and the liquid phase velocity field distribution, wherein the dynamic characteristic function comprises a coupling expression of an interface curvature item and a local vortex item; Based on the numerical distribution of the dynamic characteristic function, correcting the gas-liquid phase velocity by adopting a self-adaptive gas-liquid sliding velocity correction model; Substituting the corrected gas-liquid phase velocity into a turbulent strain rate transport equation, and solving turbulent characteristic parameters and pressure field distribution in a cavitation flow field. Further, establishing a density gradient field of the gas-liquid two-phase interface region, utilizing acoustic emission detection to identify bubble characteristics, establishing a gas-phase volume fraction distribution function, and further calculating gas-liquid two-phase mixed density; and calculating the spatial change rate of the mixed density by adopting a central differential format, identifying an interface region by combining the modulus value and the direction vector of the density gradient and the characteristic value of the second derivative tensor, and finally constructing a density gradient field representing the strength