CN116167303B - Curved surface grid interpolation method for fluid-solid coupling simulation of helicopter rotor wing - Google Patents
Curved surface grid interpolation method for fluid-solid coupling simulation of helicopter rotor wing Download PDFInfo
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Abstract
The application discloses a curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation, which comprises the following steps: triangulating rotor fluid domain object plane grid cells when the rotor fluid domain object plane grid interpolates to the rotor solid domain object plane grid; calculating the face center points of all triangulated object plane grid units of the rotor fluid domain; dividing all the face center points into a plurality of wall boxes in a dichotomy mode; according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point of the rotor solid domain and all the face center points in the wall box, a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain is found; and calculating interpolation coefficients of interpolation of the rotor fluid domain object plane grid units to corresponding rotor solid domain object plane grid points based on the shape function. Therefore, the searching efficiency is greatly improved, the interpolation accuracy is ensured, and meanwhile, the interpolation efficiency is further improved, and the method can be used for guiding the helicopter rotor wing fluid-solid coupling simulation.
Description
Technical Field
The invention relates to the field of computational fluid mechanics, in particular to a curved surface grid interpolation method for fluid-solid coupling simulation of a helicopter rotor wing.
Background
In performing fluid-solid coupling simulations of a helicopter rotor, rotor fluid and rotor solid domains require data exchange at the rotor face. However, as shown in fig. 1 and 2, the curved mesh of the rotor flow field at the object plane is not in one-to-one correspondence with the curved mesh of the rotor solid field at the object plane. At this time, interpolation is required between the two sets of curved grids to transfer data.
At present, when the method is used for fluid-solid coupling simulation of a helicopter rotor, two algorithms for interpolating between a curved grid of a rotor fluid domain on an object plane and a curved grid of a rotor solid domain on the object plane are mainly adopted, wherein the first algorithm is mapping point interpolation, and the second algorithm is radial basis interpolation. For mapping point interpolation, judging whether the foot drop of each discrete point on the interpolation surface on each grid unit of the contribution surface falls inside the grid unit of the contribution surface or not. As shown in fig. 3, when a discrete point falls inside a certain grid unit of the contribution plane, an interpolation coefficient of the grid point of the grid plane unit to the discrete point homeotropic interpolation is obtained based on a finite element method. Although the calculation result of the mapping point interpolation is accurate, the calculation time is long because all grid points of the interpolation surface and all grid units of the contribution surface need to be circulated. The radial basis interpolation needs to select a plurality of grid points of the contribution plane grid as contribution datum points and obtains interpolation coefficients by solving a linear equation set, but if the datum points are selected too little, the information of the datum points is insufficient to represent the global information of the contribution plane, and the obtained interpolation result has larger deviation; if the reference points are selected too much, the time for solving the linear equation set is long. Meanwhile, the radial basis interpolation requires that the physical quantity distribution is continuous, and if the physical quantity distribution has more discontinuities, the value difference of adjacent small areas is large, namely, the physical quantity distribution has strong local characteristics, and the radial basis interpolation result is also poor.
Disclosure of Invention
Therefore, the invention aims to provide the curved surface grid interpolation method for the fluid-solid coupling simulation of the helicopter rotor wing, which can ensure the interpolation accuracy and further improve the interpolation efficiency. The specific scheme is as follows:
a curved surface mesh interpolation method for helicopter rotor fluid-solid coupling simulation, comprising:
triangulating rotor fluid domain object plane grid cells when the rotor fluid domain object plane grid interpolates to the rotor solid domain object plane grid;
calculating the face center points of all triangulated object plane grid units of the rotor fluid domain;
dividing all the face center points into a plurality of wall boxes in a dichotomy mode;
according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point of the rotor solid domain and all the face center points in the wall box, a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain is found;
and calculating interpolation coefficients of interpolation of the rotor fluid domain object plane grid units to corresponding rotor solid domain object plane grid points based on the shape function.
Preferably, in the curved grid interpolation method for fluid-solid coupling simulation of a helicopter rotor according to the embodiment of the present invention, the method further includes:
triangulating the rotor solid domain object plane grid cells when interpolating the rotor solid domain object plane grid to the rotor fluid domain object plane grid;
calculating the face center points of all triangulated object plane grid units of the rotor wing solid domain;
dividing all the face center points into a plurality of wall boxes in a dichotomy mode;
according to the distance between each grid point of the rotor fluid domain and the wall box and the distance between each grid point and all the face center points in the wall box, a rotor solid domain grid unit corresponding to each grid point of the rotor fluid domain is found;
and calculating interpolation coefficients of interpolation of the rotor solid domain object plane grid units to corresponding rotor fluid domain object plane grid points based on the shape function.
Preferably, in the curved grid interpolation method for fluid-solid coupling simulation of a helicopter rotor according to the embodiment of the present invention, the dividing all the face center points into a plurality of wall boxes in a dichotomy mode includes:
placing all the dough points in the largest wall box; the wall box is a cuboid, and the coordinate values of eight corner points of the cuboid are determined by the maximum value and the minimum value of the center points of the face in the directions of x, y and z;
after the wall surface box is divided into two parts, dividing the wall surface box of the next layer into two parts along the maximum length direction of the center points contained in the wall surface box in the x, y and z directions;
the wall boxes are kept thin until the number of layers of the wall boxes reaches the set number of layers or the number of the face center points in the wall boxes is smaller than the square root of the total number of the face center points.
Preferably, in the curved grid interpolation method for helicopter rotor fluid-solid coupling simulation provided by the embodiment of the present invention, the finding a rotor fluid domain grid unit corresponding to each grid point of a rotor solid domain according to a distance between each grid point of the rotor solid domain and a wall box and a distance between each grid point of the rotor solid domain and all face center points in the wall box includes:
searching a wall box nearest to a grid point of a rotor wing solid domain, calculating the distance between the grid point and all face center points in the nearest wall box, finding a first nearest face center point, and recording a first distance between the grid point and the first nearest face center point;
searching a wall box next to the grid point, and stopping searching if the distance between the grid point and the next wall box is larger than the first distance; if the distance between the grid point and the searched wall box is smaller than the first distance, calculating the distance between the grid point and all the face center points in the searched wall box, and finding out a second nearest face center point;
if the second distance between the grid point and the second nearest center point is smaller than the first distance, updating the value of the first distance to the second distance;
repeating the step of searching the wall boxes until the distances between the grid points and other wall boxes are larger than the current updated distance, and stopping searching;
and finding out a rotor wing fluid domain grid unit corresponding to the grid point of the rotor wing solid domain according to the nearest center point corresponding to the distance obtained through final updating.
Preferably, in the above curved surface mesh interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the present invention, the following formula is adopted to calculate an interpolation coefficient of rotor wing fluid domain object plane mesh unit to interpolate to a corresponding rotor wing solid domain object plane mesh point:
wherein, the liquid crystal display device comprises a liquid crystal display device,
and->
For interpolation coefficients for rotor fluid domain grid cells to corresponding rotor solid domain grid points, point P is one grid point of the rotor solid domain and point A, B, C is three grid points of the rotor fluid domain grid cells corresponding to point P.
Preferably, in the curved grid interpolation method for fluid-solid coupling simulation of a helicopter rotor according to the embodiment of the present invention, the method further includes:
and calculating the distribution of the pressure coefficient of the rotor solid domain object grid according to the interpolation coefficient of the rotor fluid domain object grid unit to the corresponding rotor solid domain object grid point.
Preferably, in the curved grid interpolation method for helicopter rotor fluid-solid coupling simulation provided by the embodiment of the present invention, the finding a rotor solid domain grid unit corresponding to each grid point of a rotor fluid domain according to a distance between each grid point of the rotor fluid domain and a wall box and a distance between each grid point of the rotor fluid domain and all face center points in the wall box includes:
for one grid point of the rotor wing fluid domain, searching a wall box nearest to the grid point, calculating the distances between the grid point and all face center points in the nearest wall box, finding a first nearest face center point, and recording a first distance between the grid point and the first nearest face center point;
searching a wall box next to the grid point, and stopping searching if the distance between the grid point and the next wall box is larger than the first distance; if the distance between the grid point and the searched wall box is smaller than the first distance, calculating the distance between the grid point and all the face center points in the searched wall box, and finding out a second nearest face center point;
if the second distance between the grid point and the second nearest center point is smaller than the first distance, updating the value of the first distance to the second distance;
repeating the step of searching the wall boxes until the distances between the grid points and other wall boxes are larger than the current updated distance, and stopping searching;
and finding out a rotor wing solid domain grid unit corresponding to the grid point of the rotor wing fluid domain according to the nearest center point corresponding to the distance obtained through final updating.
Preferably, in the above curved surface mesh interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the present invention, the following formula is adopted to calculate an interpolation coefficient of rotor wing solid domain object plane mesh unit to interpolate to a corresponding rotor wing fluid domain object plane mesh point:
wherein, the liquid crystal display device comprises a liquid crystal display device,
and->
Interpolation coefficients, point +.>
Is a grid point of the rotor fluid domain, point +.>
、/>
、/>
Is +.>
Three grid points of corresponding rotor solid domain object plane grid cells.
Preferably, in the curved grid interpolation method for fluid-solid coupling simulation of a helicopter rotor according to the embodiment of the present invention, the method further includes:
and calculating the distribution of the pressure coefficient of the rotor fluid domain object plane grid according to the interpolation coefficient of the rotor solid domain object plane grid unit to the corresponding rotor fluid domain object plane grid point.
From the above technical solution, the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the invention comprises the following steps: triangulating rotor fluid domain object plane grid cells when the rotor fluid domain object plane grid interpolates to the rotor solid domain object plane grid; calculating the face center points of all triangulated object plane grid units of the rotor fluid domain; dividing all the face center points into a plurality of wall boxes in a dichotomy mode; according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point of the rotor solid domain and all the face center points in the wall box, a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain is found; and calculating interpolation coefficients of interpolation of the rotor fluid domain object plane grid units to corresponding rotor solid domain object plane grid points based on the shape function.
The curved surface grid interpolation method provided by the invention is used for guiding variable interpolation calculation between the fluid interface curved surface grid and the solid interface curved surface grid when helicopter rotor wing fluid-solid coupling simulation is performed, fully considering the locality of physical variables, particularly triangulating grid units of rotor wing fluid domains serving as contribution surfaces, calculating surface center points, dividing all the surface center points into a plurality of wall boxes by adopting a dichotomy idea, corresponding each grid point of the rotor wing solid domains serving as interpolation surfaces to the contribution surface grid units based on the wall boxes, and finally obtaining interpolation coefficients of the grid units to the corresponding object plane grid points based on a shape function to perform interpolation, thereby greatly improving search efficiency when searching the contribution surface grid units corresponding to the grid points, ensuring interpolation accuracy and further improving interpolation efficiency.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described, and it is apparent that the drawings in the following description are only embodiments of the present invention, and other drawings may be obtained according to the provided drawings without inventive effort for those skilled in the art.
FIG. 1 is a schematic view of an object plane mesh of a conventional rotor fluid field;
FIG. 2 is a schematic diagram of an object plane grid of a conventional rotor solid domain;
FIG. 3 is a schematic diagram of a conventional interpolation face grid point and contribution face unit;
FIG. 4 is one of the flow charts of a curved surface mesh interpolation method for helicopter rotor fluid-solid coupling simulation provided by an embodiment of the invention;
FIG. 5 is a schematic diagram of four-point grid cell triangularization of a contribution plane provided by an embodiment of the invention;
fig. 6 is a schematic view of a rotor fluid area object plane grid wall box according to an embodiment of the present invention;
FIG. 7a is a schematic diagram of a rotor fluid domain object plane grid in an interpolation result provided by an embodiment of the present invention;
fig. 7b is a schematic diagram of a solid-domain object plane grid of a rotor wing in an interpolation result provided by an embodiment of the present invention;
fig. 8 is a second flowchart of a curved grid interpolation method for fluid-solid coupling simulation of a helicopter rotor according to an embodiment of the invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation, which is shown in fig. 4 and comprises the following steps:
s401, triangulating rotor fluid domain object plane grid units when the rotor fluid domain object plane grid is interpolated to the rotor solid domain object plane grid.
In general, if it is necessary to interpolate data on surface mesh a to surface mesh B, a is referred to as a contribution plane, and B is referred to as an interpolation plane. In step S401, the contribution surface is the rotor fluid domain, and the interpolation surface is the rotor solid domain.
The three-dimensional grid surface unit in the numerical simulation is typically a three-point unit or a four-point unit. It is known that three points of space necessarily can fall on a certain plane. Four-point cells often have four points that are not coplanar, so the four-point cells need to be broken into two three-point cells as shown in fig. 5. If the grid cell of the contributing surface is a three-point cell, then no triangularization is required. The four-point unit has two diagonals, and when triangularization is carried out, one diagonal is selected to divide the four-point unit into two triangular units.
S402, calculating the face center points of all triangulated object plane grid units of the rotor fluid domain.
Specifically, the face center points of all grid cells of the rotor fluid domain are calculated, and the calculation method can be the arithmetic average of the coordinate values of all grid points of the grid cells.
S403, dividing all the face center points into a plurality of wall boxes in a dichotomy mode.
In specific implementation, step S403 divides all the face points into a plurality of wall boxes in a dichotomy manner, and may specifically include the following steps:
firstly, placing all the dough points in a largest wall box; the wall box is cuboid, and the coordinate values of eight corner points of the cuboid are determined by the maximum value and the minimum value of the center points of the face in the directions of x, y and z in the wall box.
After dividing the wall box into two parts, as shown in fig. 6, dividing the wall box of the next layer into two parts along the maximum length direction of the center points included in the wall box in the x, y and z directions; namely, if the maximum length direction is the y direction, sorting the face center points in the boxes according to the y coordinate value, and dividing the two boxes into half of the face center points; if the maximum length direction is the x direction, the face center points in the boxes are ordered according to the x coordinate value, and the two boxes are divided into half of the face center points respectively.
Finally, the wall box is thinned until the number of layers of the wall box reaches the set number of layers (such as 50 layers), or the number of the face center points in the wall box is smaller than the square root of the total number of the face center points.
S404, according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point and all the face center points in the wall box, a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain is found.
In a specific implementation, step S404 finds a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point and all the face center points in the wall box, and may specifically include the following steps:
for a certain grid point of the rotor wing solid domain, firstly searching a wall box nearest to the grid point, then calculating the distances between the grid point and all the face center points in the nearest wall box, finding a first nearest face center point, and recording a first distance d between the grid point and the first nearest face center point min 。
Then, searching for the wall box next to the grid point, if the distance between the grid point and the wall box next to the grid point is greater than the first distance d min The search is stopped. Because the distance between the interpolation grid point and the center point in the wall box is larger than the distance between the interpolation grid point and the wall box, and the distance between the interpolation grid point and the wall box is larger than the first distance d min So leaveThe closest centroid of the grid point is necessarily not in the wall box.
If the distance between the grid point and the searched wall box is smaller than the first distance d min The distance between the grid point and all the face center points in the current wall box is calculated, and the second nearest face center point is found.
If the second distance between the grid point and the second nearest centroid point is smaller than the first distance d min Then the first distance d min Is updated to the second distance.
And repeating the step of searching the wall boxes until the distances between the grid points and other wall boxes are larger than the current updated distance, and stopping searching.
Finally, according to the latest face center point corresponding to the distance obtained through updating, the face center of the rotor fluid domain grid cell corresponding to the grid point of each rotor solid domain can be found, namely the rotor fluid domain grid cell corresponding to the grid point of the rotor solid domain can be found.
When the rotor fluid domain grid units corresponding to each grid point are searched, the nearest rotor fluid domain face center point is found based on the wall box for each rotor solid domain object plane grid point, the grid units corresponding to the object plane grid points and the face center point are connected, and the concept of dichotomy and hierarchical search is adopted, so that the search efficiency is further improved.
S405, calculating interpolation coefficients of rotor fluid domain object plane grid points to corresponding rotor solid domain object plane grid points based on the shape function.
In the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the invention, the method is used for guiding variable interpolation calculation between the fluid interface curved surface grid and the solid interface curved surface grid during helicopter rotor wing fluid-solid coupling simulation, fully considers the locality of physical variables, triangulates grid units of rotor wing fluid domains serving as contribution surfaces, calculates face center points, divides all the face center points into a plurality of wall boxes by adopting a dichotomy idea, corresponds each grid point of the rotor wing solid domains serving as interpolation surfaces with the contribution surface grid units on the basis of the wall boxes, and finally obtains interpolation coefficients of interpolation of the grid units to the corresponding object plane grid units on the basis of a shape function so as to interpolate, when searching the contribution surface grid units corresponding to the grid points, greatly improve search efficiency, ensure interpolation accuracy and further improve interpolation efficiency.
In a specific implementation, in the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the invention, the following formula may be adopted to calculate an interpolation coefficient of rotor wing fluid domain object plane grid unit to interpolate to a corresponding rotor wing solid domain object plane grid point:
wherein, the liquid crystal display device comprises a liquid crystal display device,
and->
For interpolation coefficients for rotor fluid domain grid cells to corresponding rotor solid domain grid points, point P is one grid point of the rotor solid domain and point A, B, C is three grid points of the rotor fluid domain grid cells corresponding to point P.
Specifically, taking fig. 3 as an example, a method for calculating interpolation coefficients for interpolating rotor fluid domain grid cells to corresponding rotor solid domain grid points is described below:
let a grid point P coordinate of the rotor solid domain be
The coordinates of the three grid points a, B, C of the corresponding rotor fluid domain grid cell are: />
，/>
，
。
According to the definition of the finite element shape function:
the value of the physical quantity on the drop foot P1 is:
since in most cases the two curved surfaces of the rotor fluid and rotor solid are substantially conforming, P is very close to P1, similar to map point interpolation, assuming here:
to calculate the coefficient
And->
The perpendicular to the plane in which the P-unit ABC is located, and the foot drop is P1. P1 is parallel to AC and AB, and intersects with AB and AC at D and E, respectively.
Considering that PP1 is perpendicular to all lines on the plane of ABC, there are:
finishing formulas (5) and (6) have:
points P, A, B, CThe coordinate values of (2) are known, the vector in the formula (1) can be calculated, and the unknown number is only
And->
. By solving the system of linear equations +.>
And->
。
If the determinant of the coefficient matrix of the linear system of equations is very close to 0, then point A, B, C is substantially in a line. When the determinant absolute value of the coefficient matrix is less than 1e-10,
and->
The calculation mode of (a) is as follows:
in a specific implementation, in the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the invention, the method may further include: and calculating the distribution of the pressure coefficient of the rotor solid domain object grid according to the interpolation coefficient of the rotor fluid domain object grid unit to the corresponding rotor solid domain object grid point. Fig. 7a and 7b show schematic diagrams of interpolation results, fig. 7a corresponds to a rotor fluid domain object plane grid, and fig. 7b corresponds to a rotor solid domain object plane grid. Pressure coefficient in FIGS. 7a and 7b
The calculation formula of (2) is：/>
The method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>
As the static pressure at the grid points,
for reference pressure +.>
Reference sound speed,/->
For reference density->
As a function of the pressure coefficient,Mfor incoming stream mach number. It should be noted that only a certain physical quantity (e.g. pressure coefficient +.>
) Interpolation between two sets of curved grids; the physical quantity may be replaced by any other physical quantity (such as density, speed, pressure, temperature, deformation quantity, etc.).
In addition, it should be noted that, the process of interpolating the rotor fluid domain object plane grid to the rotor solid domain object plane grid is the same as the process of interpolating the rotor solid domain object plane grid to the rotor fluid domain object plane grid, and the implementation of interpolating the rotor solid domain object plane grid to the rotor fluid domain object plane grid can refer to the implementation of interpolating the rotor fluid domain object plane grid to the rotor solid domain object plane grid, and the repetition is not repeated. The following describes an example of interpolation of the rotor solid-domain object-plane mesh to the rotor fluid-domain object-plane mesh.
In a specific implementation, in the curved grid interpolation method for fluid-solid coupling simulation of a helicopter rotor according to the embodiment of the present invention, as shown in fig. 8, the method may further include:
s801, triangulating rotor solid domain object plane grid units when the rotor solid domain object plane grid interpolates to the rotor fluid domain object plane grid.
In step S801, the contribution surface is a rotor solid domain, and the interpolation surface is a rotor fluid domain. The three-dimensional grid surface unit in the numerical simulation is typically a three-point unit or a four-point unit. It is known that three points of space necessarily can fall on a certain plane. Four-point cells often have four points that are not coplanar, so the four-point cells need to be broken into two three-point cells as shown in fig. 5. If the grid cell of the contributing surface is a three-point cell, then no triangularization is required. The four-point unit has two diagonals, and when triangularization is carried out, one diagonal is selected to divide the four-point unit into two triangular units.
S802, calculating the face center points of all triangulated object plane grid units of the rotor wing solid domain.
Specifically, the face center points of all grid cells of the rotor solid domain are calculated, and the calculation method can be the arithmetic average of the coordinate values of all grid points of the grid cells.
S803, dividing all the face center points into a plurality of wall boxes in a dichotomy mode.
In specific implementation, step S803 divides all the face points into a plurality of wall boxes in a dichotomy manner, and may specifically include the following steps:
firstly, placing all the dough points in a largest wall box; the wall box is cuboid, and the coordinate values of eight corner points of the cuboid are determined by the maximum value and the minimum value of the center points of the face in the directions of x, y and z in the wall box.
After dividing the wall box into two parts, the wall box of the next layer is divided into two parts along the maximum length direction of the center points of the wall box in the x, y and z directions.
Finally, the wall box is thinned until the number of layers of the wall box reaches the set number of layers (such as 50 layers), or the number of the face center points in the wall box is smaller than the square root of the total number of the face center points.
S804, according to the distance between each grid point of the rotor fluid domain and the wall box and the distance between each grid point and all the face center points in the wall box, a rotor solid domain grid unit corresponding to each grid point of the rotor fluid domain is found.
In a specific implementation, according to the distance between each grid point of the rotor fluid domain and the wall box and the distance between each grid point and all the face center points in the wall box, the rotor solid domain grid unit corresponding to each grid point of the rotor fluid domain is found, which specifically includes the following steps:
for one grid point of the rotor wing fluid domain, firstly searching a wall box nearest to the grid point, then calculating the distances between the grid point and all the face center points in the nearest wall box, finding a first nearest face center point, and recording the first distance between the grid point and the first nearest face center point;
then searching a wall box next to the grid point, and stopping searching if the distance between the grid point and the next wall box is larger than the first distance; if the distance between the grid point and the searched wall box is smaller than the first distance, calculating the distance between the grid point and all the face center points in the searched wall box, and finding out the second nearest face center point. If the second distance between the grid point and the second nearest centroid point is smaller than the first distance, the value of the first distance is updated to be the second distance.
And repeating the step of searching the wall boxes until the distances between the grid points and other wall boxes are larger than the current updated distance, and stopping searching.
Finally, according to the latest face center point corresponding to the distance obtained through updating, the face center of the rotor solid domain grid cell corresponding to the grid point of each rotor fluid domain can be found, namely the rotor solid domain grid cell corresponding to the grid point of the rotor fluid domain can be found.
S805, calculating interpolation coefficients of rotor wing solid domain object plane grid points to corresponding rotor wing fluid domain object plane grid points based on the shape function.
In the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the invention, the method is used for guiding variable interpolation calculation between the fluid interface curved surface grid and the solid interface curved surface grid during helicopter rotor wing fluid-solid coupling simulation, fully considers the locality of physical variables, triangulates grid units of a rotor wing solid domain serving as a contribution surface, calculates face center points, adopts a dichotomy idea to divide all the face center points into a plurality of wall boxes, corresponds each grid point of the rotor wing fluid domain serving as an interpolation surface with the contribution surface grid units based on the wall boxes, and finally obtains interpolation coefficients of interpolation of the grid units to the corresponding object plane grid units based on a shape function so as to interpolate, when searching the contribution surface grid units corresponding to the grid points, greatly improves searching efficiency, ensures interpolation accuracy and further improves interpolation efficiency.
In a specific implementation, in the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the invention, the following formula may be adopted to calculate an interpolation coefficient of rotor wing solid domain object plane grid unit interpolation to a corresponding rotor wing fluid domain object plane grid point:
wherein, the liquid crystal display device comprises a liquid crystal display device,
and->
Interpolation coefficients, point +.>
Is a grid point of the rotor fluid domain, point +.>
、/>
、/>
Is +.>
Corresponding rotor solid domain object plane grid unitIs arranged between the grid points.
In a specific implementation, in the curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the embodiment of the invention, the method may further include: and calculating the distribution of the pressure coefficient of the rotor fluid domain object plane grid according to the interpolation coefficient of the rotor solid domain object plane grid unit to the corresponding rotor fluid domain object plane grid point.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative elements and steps are described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
In summary, the curved surface grid interpolation method for fluid-solid coupling simulation of a helicopter rotor wing provided by the embodiment of the invention comprises the following steps: triangulating rotor fluid domain object plane grid cells when the rotor fluid domain object plane grid interpolates to the rotor solid domain object plane grid; calculating the face center points of all triangulated object plane grid units of the rotor fluid domain; dividing all the face center points into a plurality of wall boxes in a dichotomy mode; according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point of the rotor solid domain and all the face center points in the wall box, a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain is found; and calculating interpolation coefficients of interpolation of the rotor fluid domain object plane grid units to corresponding rotor solid domain object plane grid points based on the shape function. The method is used for guiding variable interpolation calculation between the fluid interface curved surface grid and the solid interface curved surface grid when helicopter rotor wing fluid-solid coupling simulation is conducted, the locality of physical variables is fully considered, grid units of a rotor wing fluid domain serving as a contribution surface are triangulated firstly, then face center points are calculated, all the face center points are divided into a plurality of wall surface boxes by adopting a dichotomy idea, each grid point of the rotor wing solid domain serving as an interpolation surface corresponds to the contribution surface grid unit on the basis of the wall surface boxes, finally interpolation coefficients of interpolation of the grid units to the corresponding object plane grid points are obtained on the basis of a shape function, so that the search efficiency is greatly improved when the contribution surface grid units corresponding to the grid points are searched, the interpolation accuracy is ensured, and meanwhile the interpolation efficiency is further improved.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The curved surface grid interpolation method for helicopter rotor wing fluid-solid coupling simulation provided by the invention is described in detail, and specific examples are applied to illustrate the principle and the implementation mode of the invention, and the description of the above examples is only used for helping to understand the method and the core idea of the invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Claims (6)
1. A curved surface mesh interpolation method for fluid-solid coupling simulation of a helicopter rotor, comprising:
triangulating rotor fluid domain object plane grid cells when the rotor fluid domain object plane grid interpolates to the rotor solid domain object plane grid;
calculating the face center points of all triangulated object plane grid units of the rotor fluid domain;
dividing all the centroid points into a plurality of wall boxes in a dichotomy, comprising: placing all the dough points in the largest wall box; the wall box is a cuboid, and the coordinate values of eight corner points of the cuboid are determined by the maximum value and the minimum value of the center points of the face in the directions of x, y and z; after the wall surface box is divided into two parts, dividing the wall surface box of the next layer into two parts along the maximum length direction of the center points contained in the wall surface box in the x, y and z directions; the wall surface box is kept thin until the number of layers of the wall surface box reaches the set number of layers or the number of the face center points in the wall surface box is smaller than the square root of the total number of the face center points;
according to the distance between each grid point of the rotor solid domain and the wall box and the distance between each grid point of the rotor solid domain and all the face center points in the wall box, a rotor fluid domain grid unit corresponding to each grid point of the rotor solid domain is found;
calculating an interpolation coefficient of interpolation of the rotor fluid domain object plane grid unit to the corresponding rotor solid domain object plane grid point by adopting the following formula based on the shape function:
wherein, the liquid crystal display device comprises a liquid crystal display device,
and->
For interpolation coefficients for rotor fluid domain grid cells to corresponding rotor solid domain grid points, point P is one grid point of the rotor solid domain and point A, B, C is three grid points of the rotor fluid domain grid cells corresponding to point P.
2. The curved grid interpolation method for helicopter rotor fluid-solid coupling simulation of claim 1, further comprising:
triangulating the rotor solid domain object plane grid cells when interpolating the rotor solid domain object plane grid to the rotor fluid domain object plane grid;
calculating the face center points of all triangulated object plane grid units of the rotor wing solid domain;
dividing all the centroid points into a plurality of wall boxes in a dichotomy, comprising: placing all the dough points in the largest wall box; the wall box is a cuboid, and the coordinate values of eight corner points of the cuboid are determined by the maximum value and the minimum value of the center points of the face in the directions of x, y and z; after the wall surface box is divided into two parts, dividing the wall surface box of the next layer into two parts along the maximum length direction of the center points contained in the wall surface box in the x, y and z directions; the wall surface box is kept thin until the number of layers of the wall surface box reaches the set number of layers or the number of the face center points in the wall surface box is smaller than the square root of the total number of the face center points;
according to the distance between each grid point of the rotor fluid domain and the wall box and the distance between each grid point and all the face center points in the wall box, a rotor solid domain grid unit corresponding to each grid point of the rotor fluid domain is found;
calculating interpolation coefficients of rotor wing solid domain object plane grid points to corresponding rotor wing fluid domain object plane grid points by adopting the following formulas based on the shape function:
wherein, the liquid crystal display device comprises a liquid crystal display device,
and->
Interpolation coefficients, point +.>
Is a grid point of the rotor fluid domain, point +.>
、/>
、/>
Is +.>
Three grid points of corresponding rotor solid domain object plane grid cells.
3. The curved grid interpolation method for helicopter rotor fluid-solid coupling simulation according to claim 1, wherein said finding rotor fluid-domain grid cells corresponding to each grid point of the rotor solid domain based on the distance of each grid point of the rotor solid domain from the wall box and the distances from all the face center points in the wall box comprises:
searching a wall box nearest to a grid point of a rotor wing solid domain, calculating the distance between the grid point and all face center points in the nearest wall box, finding a first nearest face center point, and recording a first distance between the grid point and the first nearest face center point;
searching a wall box next to the grid point, and stopping searching if the distance between the grid point and the next wall box is larger than the first distance; if the distance between the grid point and the searched wall box is smaller than the first distance, calculating the distance between the grid point and all the face center points in the searched wall box, and finding out a second nearest face center point;
if the second distance between the grid point and the second nearest center point is smaller than the first distance, updating the value of the first distance to the second distance;
repeating the step of searching the wall boxes until the distances between the grid points and other wall boxes are larger than the current updated distance, and stopping searching;
and finding out a rotor wing fluid domain grid unit corresponding to the grid point of the rotor wing solid domain according to the nearest center point corresponding to the distance obtained through final updating.
4. The curved grid interpolation method for helicopter rotor fluid-solid coupling simulation of claim 1, further comprising:
and calculating the distribution of the pressure coefficient of the rotor solid domain object grid according to the interpolation coefficient of the rotor fluid domain object grid unit to the corresponding rotor solid domain object grid point.
5. The curved grid interpolation method for helicopter rotor fluid-solid coupling simulation according to claim 2, wherein said finding rotor solid domain grid cells corresponding to each grid point of the rotor fluid domain based on the distance of each grid point of the rotor fluid domain from the wall box and the distances from all the face center points in the wall box comprises:
for one grid point of the rotor wing fluid domain, searching a wall box nearest to the grid point, calculating the distances between the grid point and all face center points in the nearest wall box, finding a first nearest face center point, and recording a first distance between the grid point and the first nearest face center point;
searching a wall box next to the grid point, and stopping searching if the distance between the grid point and the next wall box is larger than the first distance; if the distance between the grid point and the searched wall box is smaller than the first distance, calculating the distance between the grid point and all the face center points in the searched wall box, and finding out a second nearest face center point;
if the second distance between the grid point and the second nearest center point is smaller than the first distance, updating the value of the first distance to the second distance;
repeating the step of searching the wall boxes until the distances between the grid points and other wall boxes are larger than the current updated distance, and stopping searching;
and finding out a rotor wing solid domain grid unit corresponding to the grid point of the rotor wing fluid domain according to the nearest center point corresponding to the distance obtained through final updating.
6. The curved grid interpolation method for helicopter rotor fluid-solid coupling simulation of claim 2, further comprising:
and calculating the distribution of the pressure coefficient of the rotor fluid domain object plane grid according to the interpolation coefficient of the rotor solid domain object plane grid unit to the corresponding rotor fluid domain object plane grid point.
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| CN115774903B (en) * | 2023-02-13 | 2023-05-26 | 中国空气动力研究与发展中心计算空气动力研究所 | Helicopter rotor disk load real-time generation method, device, equipment and medium |
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| CN115983075A (en) * | 2023-01-28 | 2023-04-18 | 西安交通大学 | Numerical simulation method for recycling bidirectional fluid-solid coupling of unmanned aerial vehicle |
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