CN-122021434-A - Tornado CFD simulation model and simulation method thereof

CN122021434ACN 122021434 ACN122021434 ACN 122021434ACN-122021434-A

Abstract

The application relates to the field of tornado simulation and discloses a tornado CFD simulation model construction method, which comprises the steps of constructing a tornado numerical wind tunnel model, setting a target tornado type and parameters, calculating a three-dimensional speed field of the target tornado through a Rankine combined vortex model to construct the target tornado field, converting the target tornado field into a function which can be recognized by CFD software through a field function and mapping the function into parameters of the numerical wind tunnel model, enabling the boundary speed of the rotary flow fan to be matched with the calculated three-dimensional speed field, constructing a three-dimensional closed fluid field, dividing grids of the closed fluid field, implementing differential grid configuration, configuring simulation parameters, solving the simulation result of the target tornado three-dimensional speed field, effectively improving the reality sense and flexibility of wind field simulation, and simultaneously considering the simulation precision and the calculation efficiency.

Inventors

CHEN DAI
XIA CHUNBO
DUAN MENGHUA
XU LEI
WANG QINGYANG
FENG JINYANG
HUANG SHUNQIAO
ZHANG QIANWEN
QIN LING
ZHANG SHAOSONG

Assignees

中国汽车工程研究院股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260130

Claims (8)

1. The method for constructing the tornado CFD simulation model is characterized by comprising the following steps of: S1, constructing a tornado numerical wind tunnel model, wherein the tornado numerical wind tunnel model comprises a polygonal outer cabin structure, a polygonal inner cabin bottom structure, a polygonal inner cabin top structure and a plurality of rotary flow fans, and the rotary flow fans are respectively arranged at the circumferential positions of the polygonal inner cabin bottom structure and the polygonal inner cabin top structure; S2, setting the type of the target tornado and wind field characterization parameters corresponding to the type, inputting the wind field characterization parameters into a Rankine combined vortex model, and calculating a three-dimensional speed field of the target tornado to construct the target tornado wind field, wherein the three-dimensional speed field comprises tangential speed, radial speed and axial speed; S3, importing the constructed tornado numerical wind tunnel model into CFD software, and converting the target tornado wind field into a boundary control function which can be identified by the CFD software through a field function, wherein the boundary control function is mapped to inlet and outlet set parameters of each rotary flow fan according to a spatial position corresponding relation, so that the boundary speed of the fan is consistent with a three-dimensional speed field generated by combining the Rankine with a vortex model; S4, in the geometric range of the tornado numerical wind tunnel model, a three-dimensional closed fluid domain is constructed by defining the fluid domains in a partition mode and connecting the fluid domains by interface boundaries, and geometric feature simplification processing is carried out on the model on the premise of keeping the flow characteristics of the tornado unchanged; s5, grid division is carried out on the three-dimensional closed fluid domains, different grid sizes are configured based on tornado flow characteristics of each fluid domain, and local grid encryption or body grid self-adaptive encryption is carried out on the key fluid domain; s6, configuring a fluid medium, a turbulence model, a time step and a convergence criterion of the three-dimensional closed fluid domain, setting a transient solution total time and a termination condition to construct a tornado transient solution working condition, and carrying out numerical solution on the tornado transient solution working condition to obtain a simulation result of the three-dimensional speed field of the target tornado.
2. The method according to claim 1, wherein the wind-field characterization parameters in step S2 include ground-level height Radial distance Angular velocity of vortex Radius of core Friction speed Length of surface roughness Karman constant 。
3. The method for constructing a tornado CFD simulation model according to claim 1, wherein in the step S2, the tangential velocity is as follows The method is described and calculated by a Rankine vortex model segment, and the calculation logic is as follows: When the radial distance is Less than or equal to the radius of the core The tangential velocity is then in the form of solid rotation: ; When the radial distance is Greater than the core radius When tangential velocity decays inversely with radius: ; Wherein, the Is radial distance The tangential velocity at which the magnetic field is generated, In order to achieve a vortex angular velocity, Is the tornado core radius.
4. The method according to claim 1, wherein in the step S2, the radial velocity is the following The method is characterized in that radial inflow or approximately zero is set according to the ground inflow characteristics of the tornados so as to simulate the contraction effect of near-ground air flow to vortex cores, and the calculation logic is as follows: ; In the formula, The maximum radial inflow velocity near the surface, the negative sign of which indicates the flow direction to the center of the vortex core; Is the influence height of the radial inflow effect; is the core radius of the tornado; is the height from the ground.
5. The method for constructing a tornado CFD simulation model according to claim 1, wherein in the step S2, the axial velocity is as follows Describing on the boundary layer log law in the near-ground boundary layer area, wherein the calculation logic is as follows: ; In the formula, Is the height from the ground; Is the friction speed; is the length of the surface roughness; Is a karman constant.
6. The method for constructing a tornado CFD simulation model according to claim 1, wherein the step S5 further comprises: For the fluid domain of the non-tornado main flow field, the grid size of the fluid domain is configured to be not lower than a preset grid size threshold value To improve the overall calculation efficiency; for the fluid domain of the tornado main flow field, the grid size of the fluid domain is set to be not more than a preset grid size threshold value To improve the calculation accuracy of the flow field core region; Local grid encryption or volume grid self-adaptive encryption is carried out in a key fluid domain so as to finely capture the vortex structure and high gradient flow characteristics of the tornado.
7. The method for constructing a tornado CFD simulation model according to claim 1, wherein the step S6 further comprises: And acquiring a three-dimensional speed field simulation result of the target tornado in actual CFD software at the key fluid field arrangement speed, pressure and turbulence monitoring points and monitoring surfaces so as to verify the consistency of the target tornado wind field constructed by the Rankine combined vortex model and the actual CFD simulation wind field.
8. A tornado CFD simulation model construction system applied to a tornado CFD simulation model construction method as claimed in claim 1, comprising: The geometric modeling module is configured to construct a tornado numerical wind tunnel model, wherein the tornado numerical wind tunnel model comprises a polygonal outer cabin structure, a polygonal inner cabin bottom structure, a polygonal inner cabin top structure and a plurality of rotary flow fans which are respectively distributed at circumferential positions of the polygonal inner cabin bottom structure and the polygonal inner cabin top structure; The wind field generation module is configured to set the type of the target tornado and wind field characterization parameters corresponding to the type, input the wind field characterization parameters into a Rankine combined vortex model, and calculate a three-dimensional speed field of the target tornado to construct the target tornado wind field, wherein the three-dimensional speed field comprises tangential speed, radial speed and axial speed; The boundary coupling module is configured to import the constructed tornado numerical wind tunnel model into CFD software, and convert the target tornado wind field into a boundary control function which can be identified by the CFD software through a field function, wherein the boundary control function is mapped to the inlet and outlet setting parameters of each rotary flow fan according to the corresponding relation of the spatial position, so that the boundary speed of the fan is consistent with the three-dimensional speed field generated by combining the Rankine with the vortex model; The grid dividing module is configured to divide the three-dimensional closed fluid domains into grids, configure differentiated grid sizes based on tornado flow characteristics of each fluid domain, and perform local grid encryption or volume grid self-adaptive encryption in a key fluid domain; The solution control module is configured to configure a fluid medium, a turbulence model, a time step and a convergence criterion of the three-dimensional closed fluid domain, set a transient solution total time and a termination condition to construct a tornado transient solution working condition, and perform numerical solution on the tornado transient solution working condition to obtain a simulation result of the three-dimensional velocity field of the target tornado.

Description

Tornado CFD simulation model and simulation method thereof Technical Field The specification relates to the field of tornado simulation, in particular to a tornado CFD simulation model and a simulation method thereof. Background Tornado is an extreme weather phenomenon with strong rotation and strong turbulence characteristics, and a wind field of the tornado has the characteristics of high speed, large shearing, strong three-dimensional vortex structure and the like, so that not only can ground buildings and infrastructure be damaged, but also serious threat can be caused to the operation safety of low-altitude aircrafts such as electric vertical take-off and landing aircrafts (eVTOL), unmanned aircrafts, light and small aircrafts and the like. With the development of low-altitude airspace and the development of urban air traffic, a need exists for obtaining reliable simulation results of the air response of tornado wind farms and low-altitude aircrafts in a controllable environment. The existing tornado research mainly depends on field observation, physical wind tunnel test and numerical simulation. The physical wind tunnel device has complex structure and limited parameter adjustment range, and is not easy to flexibly simulate the tornado wind fields with different intensities and scales on the same platform. In the aspect of numerical simulation, although a method of applying a speed boundary in an open flow field to generate a rotary flow by utilizing an analytical model such as a Rankine vortex, a Burgers vortex and the like exists, the method is mostly based on an idealized axisymmetric assumption, the coupling with a specific driving device is lacking, a calculation domain is large, the momentum is difficult to recycle, and the fidelity of a wind field, the calculation efficiency and the unification with the pneumatic simulation of a low-altitude aircraft are difficult to consider. Therefore, a tornado CFD simulation model and a simulation method thereof are needed to overcome the above problems in the prior art. Disclosure of Invention In view of the above, the invention aims to provide a tornado CFD simulation model and a simulation method thereof, so as to solve the problems of insufficient wind field restoration precision, and difficulty in balancing simulation efficiency and precision caused by the lack of a three-dimensional speed field accurate construction mechanism and a differential grid adaptation strategy of the existing tornado CFD simulation model. In order to achieve the above purpose, the invention adopts the following technical scheme: A method for constructing a tornado CFD simulation model comprises the following steps: S1, constructing a tornado numerical wind tunnel model, wherein the tornado numerical wind tunnel model comprises a polygonal outer cabin structure, a polygonal inner cabin bottom structure, a polygonal inner cabin top structure and a plurality of rotary flow fans, and the rotary flow fans are respectively arranged at the circumferential positions of the polygonal inner cabin bottom structure and the polygonal inner cabin top structure; S2, setting the type of the target tornado and wind field characterization parameters corresponding to the type, inputting the wind field characterization parameters into a Rankine combined vortex model, and calculating a three-dimensional speed field of the target tornado to construct the target tornado wind field, wherein the three-dimensional speed field comprises tangential speed, radial speed and axial speed; S3, importing the constructed tornado numerical wind tunnel model into CFD software, and converting the target tornado wind field into a boundary control function which can be identified by the CFD software through a field function, wherein the boundary control function is mapped to inlet and outlet set parameters of each rotary flow fan according to a spatial position corresponding relation, so that the boundary speed of the fan is consistent with a three-dimensional speed field generated by combining the Rankine with a vortex model; S4, in the geometric range of the tornado numerical wind tunnel model, a three-dimensional closed fluid domain is constructed by defining the fluid domains in a partition mode and connecting the fluid domains by interface boundaries, and geometric feature simplification processing is carried out on the model on the premise of keeping the flow characteristics of the tornado unchanged; s5, grid division is carried out on the three-dimensional closed fluid domains, different grid sizes are configured based on tornado flow characteristics of each fluid domain, and local grid encryption or body grid self-adaptive encryption is carried out on the key fluid domain; s6, configuring a fluid medium, a turbulence model, a time step and a convergence criterion of the three-dimensional closed fluid domain, setting a transient solution total time and a termination condition to construct a tornado transient