Method for detecting interference between film hole pairs in turbine blade film hole design stage

Abstract

The invention discloses a method for detecting interference between film hole pairs in a turbine blade film hole design stage, and the method comprises the steps: a pre-calculation stage: calculating and storing geometric parameters of all film holes, and calculating and storing a bounding box of each film hole; dividing a spatial index grid, calculating a global bounding box, and mapping all air film holes into the spatial grid; the air film hole space grids are detected in parallel, and adjacent air film holes of all the query holes are collected; rough detection is firstly carried out between the air film holes and the adjacent air film holes, and the air film holes which are completely not intersected are rapidly eliminated; and carrying out fine detection on the hole pairs subjected to rough detection, and judging the hole intersection state by calculating the axial distance and the projection length. According to the invention, automatic interference detection of a film hole arrangement scheme is realized, complex interference conditions such as parallel axes, different planes and non-parallel intersection can be effectively identified, and the problems of errors and low efficiency of traditional manual detection are avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering thermophysics, and in particular relates to a method for detecting interference between pairs of film holes in a turbine blade during the film hole design phase. Background Art

[0002] Film cooling technology is a core means of improving the high-temperature resistance of key components such as turbine blades in aircraft engines. As the operating temperature of modern aircraft engines continues to rise, traditional cooling methods can no longer meet the stringent requirements. This technology effectively isolates the direct contact between high-temperature combustion gas and the blade substrate by constructing a layer of low-temperature air film on the surface of the hot zone of the blade, thereby significantly reducing the surface temperature of the component. In the field of aircraft engines, film cooling plays an irreplaceable role in improving thermal efficiency, extending service life and ensuring flight safety, especially for extremely high-temperature areas such as high-pressure turbines and combustion chambers. The design of the cooling structure and performance optimization are directly related to the overall performance of the engine. At present, how to accurately control the distribution of air film coverage and maximize cooling efficiency has become a key research direction in engineering thermal physics and aviation power technology research.

[0003] The design method for film holes in turbine blades is to rationally arrange tiny hole structures on the blade surface, using high-pressure cooling air to form an insulating film layer on the blade surface, thereby reducing the heat load on the blade surface caused by high-temperature combustion gas. Current mainstream design methods include: 1) parametric design based on CFD simulation optimization, which uses numerical simulation to analyze the cooling efficiency under different apertures, inclination angles, hole spacing (3-5 times the aperture), and arrangement (sequential / staggered), and combines response surface methodology or genetic algorithms for multi-objective optimization; 2) composite cooling structure design, which combines film cooling with impingement cooling and convection cooling to form multi-layer cooling protection; 3) novel special-shaped hole designs, such as fan-shaped holes, water drop holes, and other non-cylindrical hole structures, which enhance the film coverage effect by changing the outlet geometry; 4) the application of additive manufacturing technology, which breaks through the limitations of traditional processing and realizes the integrated molding of complex internal cavities and special-shaped film holes. The design process requires comprehensive consideration of factors such as cooling efficiency, film stability, flow loss, and structural strength, and experimental verification (such as infrared thermal imager testing) to ensure design reliability.

[0004] When arranging film holes, it's also necessary to consider the geometric interference between them. If interference occurs, the entire cooling blade model becomes invalid. Traditional design processes typically reserve a certain amount of spacing and space margin between film holes during the design phase to prevent cross-hole interference. The turbine blades are then drilled in geometry software, and the interference between the film holes is then checked. This approach is generally not intelligent enough, and the selection of spacing margins and the checking of interference states are highly dependent on the designer's experience and observation. Furthermore, if a more complex film hole arrangement requires generation, controlling the hole row spacing alone cannot guarantee a good result. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for interference detection between pairs of film holes in the design stage of turbine blade film holes, move the interference detection link forward to the parameter design stage, and perform interference detection on all film holes, which significantly improves the design efficiency and reliability and provides an effective technical means for the design of high-density film hole layout.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A method for detecting interference between pairs of film holes in a turbine blade during the film hole design phase, characterized by comprising the following steps:

[0008] Step 1: In the pre-calculation stage, the geometric parameters of all air film holes are calculated and stored, and the bounding box of each air film hole is calculated and stored.

[0009] Step 2: Divide the spatial index grid, calculate the global bounding box, and map all air film holes into the spatial grid.

[0010] Step 3: Parallel detection of the air film hole space grid, and collection of the neighboring air film holes of all query holes.

[0011] Step 4: First, perform a rough inspection between the air film holes and the adjacent air film holes to quickly exclude the air film holes that are completely non-intersecting.

[0012] Step 5: Perform fine inspection on the hole pairs that have passed the rough inspection, and judge the intersection status of the holes by calculating the axis spacing and projection length.

[0013] Furthermore, the specific steps of precalculating and obtaining the air film hole data in step 1 include:

[0014] Step 1-1: Calculate the axial vector of the air film hole using the coordinates of the start and end points of the air film hole axis.

[0015] Step 1-2: Calculate the bounding box of each air film hole, that is, the maximum and minimum size range around the axial vector.

[0016] Step 1-3: Store all the parameters and bounding box data of the air film holes in the structure.

[0017] Furthermore, the specific steps of dividing the spatial index grid in step 2, calculating the global bounding box, and mapping all air film holes into the spatial grid include:

[0018] Step 2-1: Calculate the global bounding box and construct the space of the entire air film hole group.

[0019] Step 2-2: Generate spatial grid coordinate axes.

[0020] Step 2-3: Set an appropriate spatial mesh size to completely contain a complete air film hole cylinder and mesh the space.

[0021] Step 2-4: Initialize the spatial grid, use discretize to obtain the spatial grid index of each air film hole cylinder, and complete the mapping.

[0022] Step 2-5: Loop through all the air film holes and store the indexes of the air film holes.

[0023] Furthermore, the specific steps of performing rough detection between the air film hole and the adjacent air film holes in step 4 include:

[0024] Step 4-1: For the spatial grid where a certain air film hole is located, find its adjacent spatial grids.

[0025] Step 4-2: If there is an air film hole in the adjacent spatial grid, perform bounding box detection on it and the air film hole to be detected to detect the interference of the bounding boxes.

[0026] Step 4-3: If there are other air film holes in the spatial grid where the air film hole to be detected is located, interference detection of the bounding box is also required for them.

[0027] Step 4-4: After the rough detection is completed, the air film holes that participate in the bounding box interference detection but do not interfere with the results are put into the fine detection step.

[0028] Furthermore, the specific steps of performing fine detection on the hole pairs that pass the rough detection in step 5 include:

[0029] Step 5-1: Calculate the distance between the axis lines of the air film holes. Air film hole pairs whose distance is greater than the sum of the two air film hole radii and the set tolerance are considered to be non-intersecting.

[0030] Step 5-2: For the air film hole pairs whose axes intersect, calculate their intersection points. If the intersection points are outside the cylindrical axis segment, then the air film hole pairs do not intersect.

[0031] Step 5-3: For pairs of air film holes where the distance between their axis lines is less than the sum of the two air film hole radii plus the set tolerance, and where there is no intersection, it is necessary to calculate the projection lengths of the two axis segments onto each other.

[0032] Step 5-4: After the projection detection is completed, the duplicate intersecting hole pairs are removed and the indexes of the intersecting hole pairs are stored.

[0033] Beneficial effects of the present invention:

[0034] 1. The present invention can be used as a pre-verification tool in the air film hole design process. By detecting the interference between the designed air film holes, it avoids repeated adjustments and modifications during geometric modeling, thereby quickly completing waste design detection and rapid iteration during the design stage.

[0035] 2. The present invention avoids manual judgment and inspection of the correctness of the air film holes, and the error is far lower than manual inspection, with extremely high reliability and detection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the leaf surface mesh and its AABB bounding box.

[0037] Figure 2 Schematic diagram of the spatial discrete grid obtained by evenly dividing the leaf bounding box.

[0038] Figure 3 A schematic diagram of the target air film hole is retrieved from the surrounding grid and the neighboring air film holes are collected.

[0039] Figure 4 Schematic diagram of the air film hole being parallel to the axis.

[0040] Figure 5 Schematic diagram of the air film holes being non-parallel to the axis but in different planes.

[0041] Figure 6 Schematic diagram showing that the air film holes are not skewed and parallel to the axis, but the line segments do not intersect.

[0042] Figure 7 It is a schematic flow diagram of the present invention. DETAILED DESCRIPTION

[0043] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0044] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. Figure 7 It is a schematic flow diagram of the present invention.

[0045] Take some cylindrical surfaces with finite-length air film holes scattered in space as an example.

[0046] A method for detecting interference between pairs of film holes in a turbine blade during the film hole design phase comprises the following steps:

[0047] Step 1: In the pre-calculation stage, the geometric parameters of all air film holes, such as the coordinates of the exit and entry points, and the direction vector of the air film hole are calculated and stored. The bounding box of each air film hole is calculated and stored. The average size of the air film hole enclosure is calculated and multiplied by a redundancy coefficient to obtain the spatial grid size, which needs to be larger than the size of any air film hole.

[0048] Step 2: Divide the spatial index grid and calculate the global bounding box of the turbine blade space, such as Figure 1As shown, the space of the entire air film hole group is constructed, and then the spatial grid coordinate axis is generated. The pre-calculated spatial grid size is set to completely contain a complete air film hole cylinder. The space is evenly divided and all air film holes are mapped to the spatial grid. The spatial grid is initialized, as shown in Figure 2 Use the discretize command to traverse all the film holes, obtain the spatial grid index of each film hole cylinder, and complete the mapping of the film holes to the spatial grid.

[0049] Step 3: For each air film hole, query its index in the spatial grid and collect all its neighboring air film holes. The principle is as follows: Figure 3 As shown, dark gray is the grid mapped to the target air film hole, and light gray is the grid around it. Air film hole 2 is in the light gray grid and will be collected as a neighboring air film hole in the proximity detection, while air film hole 3 is in the white non-neighboring grid and will not be collected.

[0050] Step 4: During the rough detection phase, parallel computing is used to accelerate detection. For each air film hole, the intersection of their bounding boxes is calculated with those of its neighbors. If the intersection is empty, there is no intersection between the air film holes; otherwise, there is a possibility of intersection. This method can quickly eliminate completely non-intersecting air film holes, reducing the number of air film holes required for fine detection.

[0051] Step 5: Perform fine detection on the hole pairs that fail the rough detection. Part of it is to calculate the minimum distance between the air film hole axes, and part of it is to judge whether there is an actual overlapping area between the air film holes. When the minimum distance between the air film hole axes is greater than the sum of the two radii and the tolerance, there is no overlap of the air film holes; when the minimum distance between the air film hole axes is greater than the sum of the two radii and the tolerance, there are two cases. This is because the air film holes are actually of finite length. Although the minimum distance between the axes exceeds the limit, there may still be no intersection for the actual air film holes. At this time, it is necessary to call the projection algorithm between line segments for detection. When both tests get the result of the air film holes intersecting, they return fasle and store the index of the corresponding air film hole pair. There are three possible non-intersecting states between the air film hole pairs as follows Figure 4 , as shown in Figures 5 and 6.

[0052] The present invention first obtains the geometric parameters and spatial bounding boxes of all air film holes through pre-calculation, and establishes a global spatial index grid; it adopts a two-level detection mechanism of "coarse detection + fine detection", first quickly screens adjacent hole pairs through the spatial grid and performs a preliminary judgment of bounding box interference, and then accurately calculates the axis distance and projection length of the potential interfering hole pairs. The present invention realizes automated interference detection of air film hole layout schemes, and can effectively identify complex interference situations such as parallel, skewed, and non-parallel intersections of axes, avoiding the errors and inefficiencies of traditional manual inspection. Compared with traditional empirical design methods, the present invention moves the interference detection link forward to the parameter design stage, significantly improving design efficiency and reliability, and providing an effective technical means for the design of high-density air film hole layouts.

Claims

1. A method for detecting interference between pairs of film holes in a turbine blade during the film hole design phase, characterized in that: The following steps are involved: 1) Pre-calculation stage: calculate and store the geometric parameters of all air film holes, and calculate and store the bounding box of each air film hole; 2) Divide the spatial index grid, calculate the global bounding box, and map all air film holes to the spatial grid; 3) Parallel detection of the air film hole space grid, collecting the air film holes adjacent to all query holes; 4) First, perform a rough inspection between the air film holes and the adjacent air film holes to quickly eliminate the air film holes that are completely non-intersecting; 5) Perform fine inspection on the hole pairs that pass the rough inspection, and judge the intersection status of the holes by calculating the axis spacing and projection length.

2. The method for detecting interference between pairs of film holes in the design phase of turbine blade film holes according to claim 1, characterized in that: The specific steps of precalculating and obtaining the air film hole data in step 1) include: 1-1) Calculate the axial vector of the air film hole by the coordinates of the starting point and end point of the air film hole axis; 1-2) Calculate the bounding box of each air film hole, that is, the maximum and minimum size range around the axial vector; 1-3) Store all air film hole parameters and bounding box data in the structure.

3. The method for detecting interference between pairs of film holes in the design phase of turbine blade film holes according to claim 1, characterized in that: The specific steps of dividing the spatial index grid, calculating the global bounding box, and mapping all air film holes to the spatial grid in step 2) include: 2-1) Calculate the global bounding box and construct the space of the entire air film hole group; 2-2) Generate spatial grid coordinate axes; 2-3) Set an appropriate spatial grid size to completely contain a complete air film hole cylinder and mesh the space; 2-4) Initialize the spatial grid and use the discretize command to obtain the spatial grid index of each air film hole cylinder to complete the mapping; 2-5) Loop through all the air film holes and store the indexes of the air film holes.

4. The method for detecting interference between pairs of film holes in the design phase of turbine blade film holes according to claim 1, characterized in that: The specific steps of performing rough detection between the air film hole and the adjacent air film holes in step 4) include: 4-1) For a certain air film hole, find its adjacent space grids; 4-2) If there is an air film hole in the adjacent spatial grid, perform bounding box detection on it and the air film hole to be detected, and check the bounding box interference; 4-3) If there are other air film holes in the spatial grid where the air film hole to be inspected is located, then the interference detection of the bounding box is also required for them; 4-4) After the rough detection is completed, the air film holes that participate in the bounding box interference detection but do not interfere with the results are put into the fine detection step.

5. The method for detecting interference between pairs of film holes in the design phase of turbine blade film holes according to claim 1, characterized in that: The specific steps of performing fine detection on the hole pairs that pass the rough detection in step 5) include: 5-1) Calculate the distance between the axis of the air film holes. If the distance is greater than the sum of the two air film hole radii and the setting tolerance, the air film hole pairs are considered to be non-intersecting. 5-2) For pairs of air film holes with intersecting axes, calculate their intersection point. If the intersection point is outside the cylindrical axis segment, then the air film hole pair does not intersect; 5-3) For pairs of film hole axes where the distance between them is less than the sum of the two film hole radii plus the setting tolerance, and where there is no intersection, the projection lengths of the two axis segments onto each other need to be calculated. 5-4) After the projection detection is completed, the repeated intersecting hole pairs are removed and the indexes of the intersecting hole pairs are stored.

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