A method for measuring throat area of a turbine guide vane

Abstract

The application provides a turbine guide vane throat area measurement method, and belongs to the technical field of gas turbine design. The method comprises the following steps: determining a vane characteristic strip where a turbine guide vane theoretical model flow passage characteristic point is located; marking the position of the vane characteristic strip on the turbine guide vane; photographing the vane characteristic strip at a fixed angle to obtain a vane characteristic strip image; obtaining a flow passage surface state parameter in the vane characteristic strip by analyzing the image; measuring the window width and the window height of each section of the turbine guide vane; and calculating the throat area of a single channel of the turbine guide vane according to the measured window width and window height and the vane surface state parameter. The turbine guide vane throat area measurement method provided by the application considers the vane surface state in view of the rough and uneven vane surface after use, and the measurement accuracy of the turbine guide vane throat area can be improved by calculating the turbine guide vane throat area by using the method.

Description

Technical Field

[0001] This application belongs to the field of aero-engine design technology, and specifically relates to a method for measuring the throat area of ​​a turbine guide vane. Background Technology

[0002] The throat area of ​​the turbine guide vane is an important parameter that determines the overall performance of the engine. It directly affects the temperature before and after the turbine stage, the airflow field, and the engine's flow rate, thrust, speed, and fuel consumption. It has a great impact on the stable operation of the engine and the matching performance between the compressor and the turbine.

[0003] Currently, the throat area measurement of engine turbine guide vanes mainly employs specialized ranging tools and a three-coordinate measuring machine (CCM) method. This method calculates the throat area by measuring a finite number of theoretical points along the blade cascade window throat. However, this method is only suitable for newly manufactured, unused blades. Because new blades have good surface quality and relatively uniform roughness, the calculation results are relatively accurate. But when blades have been used and factors such as adhesion, ablation, etc., cause the blade flow channel surface to exhibit an uneven morphology, the aforementioned throat area calculation method will result in significant differences in the throat area measurement, leading to substantial errors. Summary of the Invention

[0004] The purpose of this application is to provide a method for measuring the throat area of ​​a turbine guide vane, so as to solve or alleviate at least one of the problems in the prior art.

[0005] The technical solution of this application is: a method for measuring the throat area of ​​a turbine guide vane, comprising:

[0006] Determine the blade feature stripe where the flow channel feature points of the turbine guide vane theoretical model are located;

[0007] The locations of the blade feature stripes are marked on the turbine guide vanes. The blade feature stripes are photographed at a fixed angle to obtain images of the blade feature stripes. The flow channel surface state parameters within the blade feature stripes are obtained by analyzing the images.

[0008] Measure the window width and window height of each section of the turbine guide vane;

[0009] The throat area of ​​a single channel of the turbine guide vane is calculated based on the measured window width and height, as well as the blade surface condition parameters.

[0010] In a preferred embodiment of this application, the process of determining the blade feature strip where the flow channel feature points of the turbine guide vane theoretical model are located is as follows:

[0011] A three-dimensional geometric model of the outer flow channel surface of adjacent turbine guide vanes was established using 3D modeling software.

[0012] On the turbine guide blade between the upper and lower edge flow channel surfaces of the three-dimensional geometric model, n equally spaced cylinders with the engine axis X as the axis are selected. The outer surface of the turbine guide blade is cut through the equally spaced cylinders to obtain n sets of basin-side and back-side profiles.

[0013] Measure the minimum distance between the profile lines on the pot side and the back side of each group of adjacent leaves. The line segment containing the minimum distance is the width line segment, and the two endpoints of the width line segment are the width feature points.

[0014] The intersection of the line connecting the midpoints of the width segments at the top and bottom with the flow channel surfaces of the upper and lower edge plates is the height characteristic point, and the line segment between the height characteristic points is the height line segment.

[0015] Connect n width feature points on one side from the leaf tip to the leaf root, and obtain a leaf body feature curve on both the pot side and the back side of the leaf. Offset the leaf body feature curves to the left and right along the leaf profile by a predetermined length to obtain the pot-back side leaf body feature strip.

[0016] Draw a plane perpendicular to the engine's Y-axis through the height feature point. Select a line segment of a predetermined length on the intersection line of the plane and the flow channel surface of the edge plate. This line segment is the edge plate feature curve. The height feature point is located in the center of this line segment. Offset the edge plate feature curve circumferentially by a predetermined length along the flow channel surface of the edge plate to obtain the upper and lower edge plate feature strips.

[0017] In a preferred embodiment of this application, the number of equally spaced cylinders is 3 to 7.

[0018] In a preferred embodiment of this application, the process of parsing the image to obtain the blade surface state parameters within the blade feature strips is as follows:

[0019] The image is processed into grayscale using special feature stripes;

[0020] A model is pre-established to show the relationship between the surface height of different characteristic stripes on the blade and their grayscale values.

[0021] Based on the relationship model between the surface height of different feature stripes of the blade and the gray value, calculate the surface height value Z(x,y) corresponding to the coordinates (x,y) of a certain gray point in the image;

[0022] Calculate the average surface height at the corresponding positions on the leaf blade back side and upper and lower edge plates, as well as at the theoretical profile.

[0023] In the formula, the subscripts i = h and W correspond to the width feature strip and the height feature strip, respectively;

[0024] j = s, x, p, b, which correspond to the upper edge plate, lower edge plate, basin side, and back side, respectively;

[0025] k = 1 and 2, respectively, correspond to the entire feature strip and the theoretical shape line position within the feature strip;

[0026] A ijk This represents the area of ​​the corresponding strip region;

[0027] Z ijk (x, y) represents the corresponding surface height value.

[0028] In a preferred embodiment of this application, the lengths of the width segments and height segments of each cross-section of the turbine guide vane are measured using a measuring instrument or a coordinate measuring machine.

[0029] In a preferred embodiment of this application, the throat area of ​​a single channel of the turbine guide vane is calculated as follows:

[0030] S hk =S hsk +S hxk k = 1, 2

[0031] S wk =S wpk +S wbk k = 1, 2

[0032]

[0033] The method for measuring the throat area of ​​turbine guide vanes provided in this application takes into account the rough and uneven surface of the blades after use. Calculating the throat area of ​​turbine guide vanes using this method can improve the accuracy of the measurement of the throat area of ​​turbine guide vanes. Attached Figure Description

[0034] To more clearly illustrate the technical solutions provided in this application, the accompanying drawings will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application.

[0035] Figure 1 This is a schematic diagram of the method for measuring the throat area of ​​the turbine guide vane according to this application.

[0036] Figure 2 This is a schematic diagram of the equally spaced cylinder and turbine guide vanes in this application.

[0037] Figure 3 This is a schematic diagram of the width and height line segments in this application.

[0038] Figure 4 This is a schematic diagram of the leaf blade feature stripes in this application.

[0039] Figure 5 This is a schematic diagram of the characteristic stripe of the rim plate in this application. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings.

[0041] To address the issue of rough and uneven blade surfaces after use, which leads to significant errors when using coordinate measuring machines (CMMs), this application provides a method for measuring the throat area of ​​turbine guide vanes that takes into account the surface condition of the blades.

[0042] like Figure 1 As shown, the method for measuring the throat area of ​​a turbine guide vane provided in this application includes the following steps:

[0043] Step 1: Determine the blade feature strip where the flow channel feature points of the turbine guide vane theoretical model are located.

[0044] 1) Use 3D modeling software to establish a 3D geometric model of the outer flow channel surface of adjacent turbine guide vanes;

[0045] 2) such as Figure 2 As shown, n equally spaced cylinders with the engine axis X as the axis are selected on the turbine guide vane 1 between the upper edge plate flow channel surface 2 and the lower edge plate flow channel surface 3. The outer surface of the turbine guide vane 1 is cut to obtain n sets of basin-side and back-side profiles 4. In the preferred embodiment of this application, the number of equally spaced cylinders is 3 to 7.

[0046] For example, in the illustrated embodiment of this application, n=3, that is, three equally spaced cylinders are selected to cut the turbine guide blade, thereby obtaining three sets of basin-side and back-side profiles.

[0047] 3) such as Figure 3 As shown, the minimum distance between the basin side and back side profile 4 of each group of adjacent blades is measured. The line segment where the minimum distance is located is called the width line segment 7, and its two endpoints are the width feature points 5.

[0048] 4) The intersection of the line connecting the midpoint of the width segment 7 at the top and bottom with the upper edge plate flow channel surface 2 and the lower edge plate flow channel surface 3 is called the height feature point 6, and the line segment between the height feature points 6 is called the height segment 8.

[0049] 5) Combining Figure 3 and Figure 4 As shown, from the leaf tip to the leaf root, connect the width feature point 5, and obtain a leaf body feature curve 9 on the leaf body side and the back side of the leaf. The leaf body feature curve 9 is offset to the left and right along the leaf shape line by a predetermined length L (for example, the offset can be set to 2mm) to obtain the leaf body feature strip on the back side of the leaf body.

[0050] 6) such as Figure 5As shown, draw a plane perpendicular to the engine's Y-axis (X-axis is the engine's axis of rotation, Z-axis is the engine's radial direction, and the Y-axis direction is determined by the right-hand rule of Z*X) through the height feature point 6. Select a line segment of length D (for example, this length can be 5mm) on the intersection line of the plane and the flange flow channel surface. This line segment is the flange feature curve 10, with the height feature point 6 located at the center of this line segment. Offset the flange feature curve 10 circumferentially by a length L (for example, an offset of 2mm can be set) along the flange flow channel surface to obtain the upper and lower flange feature strips 11.

[0051] Step 2: Measure and calculate the blade surface state parameters within the blade characteristic stripes.

[0052] The locations of the blade feature stripes are marked on the turbine guide vane. High-precision cameras or microscopes (such as CCD cameras, metallurgical microscopes, etc.) are used to take pictures of the blade feature stripes at a fixed angle to obtain images of the blade feature stripes. The surface state parameters of the blade within the blade feature stripes are obtained by analyzing the images.

[0053] The process of parsing this image is as follows:

[0054] 2.1) Read the captured image, segment and extract the leaf feature strip regions in the image;

[0055] 2.2) Perform preprocessing on the image, such as noise filtering and sharpening enhancement, including but not limited to homomorphic filtering, Gaussian filtering, Laplace sharpening, median filtering, histogram equalization, etc.

[0056] 2.3) Perform grayscale processing on the image, representing the pixel values ​​in the image using 0-255;

[0057] 2.4) A model relating the surface height of different feature stripes on the blade to gray values ​​can be established in advance. This can be achieved by establishing a BP neural network and training the neural network to realize the mapping between surface height and gray values.

[0058] 2.5) Based on the relationship model between the surface height of different feature stripes of the blade and the gray value, calculate the surface height value Z(x,y) corresponding to the coordinates (x,y) of a certain gray point in the image;

[0059] 2.6) Calculate the average surface height S at the corresponding positions on the leaf blade back side and upper and lower edge plates, as well as at the theoretical profile. ijk The calculation method is as follows:

[0060]

[0061] In the formula, the subscripts i = h and W correspond to the width feature strip and the height feature strip, respectively;

[0062] j = s, x, p, b, which correspond to the upper edge plate, lower edge plate, basin side, and back side, respectively;

[0063] k = 1 and 2, respectively, correspond to the entire feature strip and the theoretical shape line position within the feature strip;

[0064] A ijk This represents the area of ​​the corresponding strip region;

[0065] Z ijk (x, y) represents the corresponding surface height value.

[0066] For example, in this embodiment of the application, the blade surface state parameters obtained through the above process are shown in Table 1:

[0067] Table 1 Blade surface condition parameters

[0068]

[0069] Step 3: Measure the width and height of the larynx window.

[0070] Measure the length of the width line segment of each section of the turbine guide vane (i.e., the window width W). i The length of the height line segment (i = 1 to n) and the height line segment length (i.e., window height H) can be measured using existing measuring tools or coordinate measuring machines.

[0071] Step 4: Calculate the throat area of ​​a single turbine guide vane.

[0072] The throat area of ​​a single passage of the turbine guide vane is calculated based on the actual measured window width and height, as well as the flow channel surface condition parameters.

[0073] S hk =S hsk +S hxk k = 1, 2

[0074] S wk =S wpk +S wbk k = 1, 2

[0075]

[0076] Based on the above process, the throat area of ​​the turbine guide vane in this embodiment of the application can be obtained, as shown in Table 2:

[0077] Table 2 Throat area of ​​a single window on the blade

[0078] <![CDATA[Window width W1 (mm)]]> 9.82 <![CDATA[Window width W2 (mm)]]> 9.67 <![CDATA[Window width W3 (mm)]]> 9.59 Window height H (mm) 40.60 <![CDATA[Throat area F (mm 2 )]]> 384.1247

[0079] The method for measuring the throat area of ​​turbine guide vanes provided in this application takes into account the rough and uneven surface of the blades after use. Calculating the throat area of ​​turbine guide vanes using this method can improve the accuracy of the measurement.

[0080] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for measuring the throat area of ​​a turbine guide vane, characterized in that, The method includes: Step 1: Determine the blade feature stripes where the flow channel feature points of the turbine guide vane theoretical model are located, including: A three-dimensional geometric model of the outer flow channel surface of adjacent turbine guide vanes was established using 3D modeling software. On the turbine guide blade between the upper and lower edge flow channel surfaces of the three-dimensional geometric model, n equally spaced cylinders with the engine axis X as the axis are selected. The outer surface of the turbine guide blade is cut through the equally spaced cylinders to obtain n sets of basin-side and back-side profiles. Measure the minimum distance between the profile lines on the pot side and the back side of each group of adjacent leaves. The line segment containing the minimum distance is the width line segment, and the two endpoints of the width line segment are the width feature points. The intersection of the line connecting the midpoints of the width segments at the top and bottom with the flow channel surfaces of the upper and lower edge plates is the height characteristic point, and the line segment between the height characteristic points is the height line segment. Connect n width feature points on one side from the leaf tip to the leaf root, and obtain a leaf body feature curve on both the pot side and the back side of the leaf. Offset the leaf body feature curves to the left and right along the leaf profile by a predetermined length to obtain the pot-back side leaf body feature strip. Draw a plane perpendicular to the engine's Y-axis through the height feature point. Select a line segment of a predetermined length on the intersection line of the plane and the flow channel surface of the edge plate. This line segment is the edge plate feature curve. The height feature point is located in the center of this line segment. Offset the edge plate feature curve circumferentially by a predetermined length along the flow channel surface of the edge plate to obtain the upper and lower edge plate feature strips. Step 2: Mark the location of the blade feature stripes on the turbine guide vane, take pictures of the blade feature stripes at a fixed angle to obtain images of the blade feature stripes, and obtain the flow channel surface state parameters within the blade feature stripes by analyzing the images. Step 3: Measure the window width and window height of each section of the turbine guide vane; Step 4: Calculate the throat area of ​​a single channel of the turbine guide vane based on the measured window width and height, as well as the blade surface condition parameters.

2. The method for measuring the throat area of ​​a turbine guide vane as described in claim 1, characterized in that, The number of equally spaced cylinders is 3 to 7.

3. The method for measuring the throat area of ​​a turbine guide vane as described in claim 1 or 2, characterized in that, The process of parsing this image to obtain the blade surface state parameters within the blade feature bands is as follows: Perform grayscale processing on the leaf feature strip image; A model is pre-established to show the relationship between the surface height of different characteristic stripes on the blade and their grayscale values. Based on the relationship model between the surface height of different feature stripes of the blade and the gray value, the surface height value Z(x,y) corresponding to the coordinates (x,y) of a certain gray point in the image is calculated. Calculate the average surface height at the corresponding position on the back side of the leaf blade, the average surface height at the corresponding position within the characteristic strips of the upper and lower edge plates, and the average surface height at the corresponding position of the theoretical profile. , In the formula, the subscripts i=h and W, which correspond to the height feature strip and the width feature strip, respectively; j = s, x, p, b, which correspond to the upper edge plate, lower edge plate, basin side, and back side, respectively; k=1 and 2 correspond to the entire feature strip and the corresponding theoretical profile position within the feature strip, respectively; This represents the area of ​​the corresponding strip region; Z ijk (x, y) represents the corresponding surface height value.

4. The method for measuring the throat area of ​​a turbine guide vane as described in claim 3, characterized in that, The lengths of the width and height segments of each section of the turbine guide vane are measured using a measuring instrument or a coordinate measuring machine.

5. The method for measuring the throat area of ​​a turbine guide vane as described in claim 4, characterized in that, The method for calculating the throat area of ​​a single passage in a turbine guide vane is as follows: ； ； ； In the formula, W i H is the width of the i-th window; H is the height of the window.

Images