Impeller detection system and detection method

Abstract

The invention discloses an impeller detection system and a detection method. The detection system comprises a working platform, a clamping mechanism is provided on the working platform for clamping the impeller, the clamping mechanism can be rotatably arranged on the working platform to rotate the impeller, a fixing column is vertically provided on the working platform, a laser displacement sensor and a rotation speed sensor are provided on the fixing column, the laser displacement sensor is used to measure the distance from the laser displacement sensor to the impeller to be measured position, a reflective sheet corresponding to the rotation speed sensor is provided on the clamping mechanism, and it is convenient to cooperate with the rotation speed sensor to measure the number of revolutions of the impeller; the laser displacement sensor and the rotation speed sensor have the same data acquisition frequency and are respectively connected to the detection unit, so as to facilitate the transmission of the measurement data to the detection unit, so that the detection unit can detect and analyze the eccentricity and ellipticity of the impeller, the eccentricity of the blade, the deformation degree of the blade profile and the uniformity of the blade distribution, and the detection accuracy is high and the detection efficiency is high.

Description

Technical Field

[0001] The invention belongs to the field of detection technology, and in particular relates to an impeller detection system and a detection method. Background Art

[0002] The impeller is one of the core components of power machinery and is widely used in power equipment such as turbine engines, turbine machinery, centrifugal compressors, etc.

[0003] High-precision dimensional detection of impellers has always been a major problem that has troubled engineers. Current monitoring methods can only measure extremely limited and regular-shaped dimensions of the impeller, such as the outer diameter, inner diameter, flow channel width, and pitch. It is difficult to effectively detect special-shaped parts such as blade shapes.

[0004] Based on this, how to perform all-round detection of the impeller while improving the detection accuracy and detection efficiency is a technical problem that technical personnel in this field hope to solve. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide an impeller detection system and detection method, which can detect and analyze the eccentricity and ovality of the impeller, the eccentricity of the blades, the deformation of the blade profile and the uniformity of the blade distribution with high detection accuracy and high detection efficiency.

[0006] The technical solution of the present invention is achieved in this way:

[0007] An impeller detection system includes a working platform, wherein a clamping mechanism is provided on the working platform for clamping an impeller, wherein the clamping mechanism is rotatably arranged on the working platform to rotate the impeller, and a fixing column is vertically provided on the working platform, wherein a laser displacement sensor and a rotation speed sensor are provided on the fixing column, wherein the laser displacement sensor is used to measure the distance from the laser displacement sensor to a position to be measured of the impeller, and a reflective sheet corresponding to the rotation speed sensor is provided on the clamping mechanism, so as to cooperate with the rotation speed sensor to measure the number of revolutions of the impeller; the laser displacement sensor and the rotation speed sensor have the same data acquisition frequency and are respectively connected to a detection unit, so as to facilitate the transmission of measurement data to the detection unit, so that the detection unit can detect and analyze the eccentricity and ellipticity of the impeller, the eccentricity of the blade, the deformation degree of the blade profile and the uniformity of the blade distribution.

[0008] Furthermore, the clamping mechanism is rotatably arranged on the working platform through a transmission mechanism; the transmission mechanism includes a motor and a reduction gear box, and the motor and the reduction gear box are arranged below the working platform, the motor output shaft is connected to the reduction gear box, and an axial hole is provided on the working platform that passes through the upper and lower surfaces of the working platform and corresponds to the transmission shaft of the reduction gear box, the transmission shaft of the reduction gear box extends out of the axial hole of the working platform and is connected to the center of the clamping mechanism, so that the motor is started, thereby driving the clamping mechanism to rotate, and then driving the impeller to rotate.

[0009] Furthermore, a bearing is provided between the working platform and the clamping mechanism, and the bearing sleeve is arranged on the transmission shaft of the reduction gear box and is fixedly connected to the clamping mechanism; a spirit level is provided on the working platform, and leveling screws are respectively provided at the four corners of the working platform, so that the leveling screws can be adjusted by observing the spirit level to make the working platform in a horizontal state.

[0010] An impeller detection method is provided, which uses the above-mentioned impeller detection system to perform detection, marks the position of the impeller ring as the detection position 1, marks the position of the impeller blade as the detection position 2, and the circumferential direction corresponding to the detection position 1 and the detection position 2 has a plurality of detection points; specifically, the following steps are included:

[0011] S1: Place the laser displacement sensor at the position 1 to be measured. After the impeller speed is stable, start the detection unit to synchronously collect the distance from the laser displacement sensor to the position 1 to be measured and the impeller speed. The collected data is processed based on the 3σ principle, and then the eccentricity and ovality of the impeller are detected and analyzed.

[0012] S2: Repeat step S1 to perform multiple detection and analysis, and output the detection results;

[0013] S3: Place the laser displacement sensor at the position 2 to be measured. After the impeller speed is stable, start the detection unit to synchronously collect the distance from the laser displacement sensor to the position 2 to be measured and the impeller speed. The collected data is processed based on the 3σ principle, and then the blade eccentricity, blade profile deformation and blade distribution uniformity are detected and analyzed.

[0014] S4: Repeat step S4 to perform multiple detection and analysis and output the detection results.

[0015] Furthermore, the detection and analysis of step S1 and step S3 include the following steps:

[0016] (1) Calculate t i The distance R between the measured point and the rotation center at the measured position at the moment i and the impeller rotation angle θ i ;

[0017] R i =ll i

[0018]

[0019] Where: l is the distance between the laser displacement sensor and the rotation center;

[0020] l i is the distance between the laser displacement sensor and the position to be measured on the impeller;

[0021] t1 and t2 are the start and end time of data collection respectively;

[0022] n1 is the number of reflective sheet signals during the time period t2-t1;

[0023] (2) Establish a coordinate system with the impeller rotation center as the coordinate origin. The coordinates of any point to be measured at the measured position are (x i ,y i ), where x i =R i cosθ i ;y i =R i sinθ i The eccentricity e1 and ellipticity d of the impeller are calculated by fitting the circle equation and the ellipse equation by the least square method respectively; the blade profile is fitted to calculate the deformation B1 and unevenness C1 of the impeller blade, and the eccentricity e2 of the impeller blade is calculated by fitting the circle by the least square method.

[0024] Furthermore, when calculating the impeller eccentricity, the impeller fitting center coordinates (x c ,y c ) and the impeller rotation center deviation formula:

[0025] ming(R i ,θ i )=∑((x i -x c ) 2 +(y i -y c ) 2 -R 2 )

[0026] Where: R is the radius of the fitting circle;

[0027] Adjust x several times c ,y c and R values ​​make ming(R i ,θ i ) is the smallest, thus obtaining the fitting center coordinate (x c ,y c ), and then the impeller eccentricity e1 is calculated as:

[0028] Further, when calculating the impeller ovality, the following steps are included:

[0029] Based on the ellipse equation Ax i 2 +Bx i y i +Cy i 2 +Dx i +Ey i +F=0, adjust the values ​​of A, B, C, D, E and F, and change the coordinates of the point to be measured (x i ,y i ) into the ellipse equation, so that Ax i 2 +Bx i y i +Cy i 2 +Dx i +Ey i The value of +F approaches 0, thus obtaining the values ​​of A, B, C, D, E and F at this time;

[0030] Then the geometric center coordinates (x T ,y T ),in Thus we get the major and minor axes a and b of the ellipse: Then the ellipticity d is:

[0031] Furthermore, when calculating the eccentricity of the impeller blade, the following steps are included: taking the rotation center as the coordinate origin, in the radial direction of the impeller, n2 circles are determined at a certain interval, and each circle corresponds to a number of points to be measured, and the least squares method is used to fit the circle to obtain the fitting center (x cm ,y cm ), then the impeller blade eccentricity e2 is:

[0032] Furthermore, the impeller blade deformation B1:

[0033]

[0034] Where: x i0 ,y i0 are the coordinates of the points to be measured on the blade profile (x i ,y i ) corresponding to the horizontal and vertical coordinates of the standard blade profile;

[0035] k is the total number of points to be measured.

[0036] Furthermore, when analyzing the uneven distribution of blades, the rotation center is taken as the coordinate origin. In the radial direction of the impeller, n3 circles are determined at a certain interval and each blade is numbered, marked as 1, 2, 3...j in sequence. Under the same radius, the distance between blade 2 and blade 1 is recorded as d1, the distance between blade 3 and blade 2 is recorded as d2, and the distance between blade 1 and blade j is recorded as d j ; Then the unevenness C1 of the impeller blade is:

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. The present invention adopts the least square method to fit the circle equation and the least square method to fit the ellipse equation to calculate the eccentricity and ellipticity of the impeller, and fits the blade profile to calculate the deformation and unevenness of the impeller blades, and adopts the least square method to fit the circle to calculate the eccentricity of the impeller blades, thereby effectively detecting the impeller, ensuring the manufacturing accuracy of the impeller, improving the performance of the impeller, and having high detection accuracy and high detection efficiency.

[0039] 2. The detection system described in the present invention has a simple structure, is easy to operate, has strong practicality, and is suitable for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 -Schematic diagram of the structure of the detection system of the present invention.

[0041] Figure 2 -Blade profile diagram.

[0042] Figure 3 -Schematic diagram of the circle determining the blade eccentricity.

[0043] Figure 4 - Schematic diagram of impeller blade profile and blade standard profile.

[0044] Among them: 1-working platform; 2-clamping mechanism; 3-impeller; 4-motor; 5-reduction gearbox; 6-bearing; 7-level; 8-leveling screw; 9-fixing column; 10-speed sensor; 11-laser displacement sensor; 12-detection unit; 13-reflective sheet; 001-position to be measured 1; 002-position to be measured 2. DETAILED DESCRIPTION

[0045] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0046] See also Figure 1, an impeller detection system, including a work platform 1, a clamping mechanism 2 is provided on the work platform 1 for clamping an impeller 3, the clamping mechanism 2 can be rotatably arranged on the work platform 1 to rotate the impeller 3, a fixing column 9 is vertically provided on the work platform 1, a laser displacement sensor 11 and a rotation speed sensor 12 are provided on the fixing column 9, the laser displacement sensor 11 is used to measure the distance from the laser displacement sensor 11 to the position to be measured of the impeller 1, a reflective sheet 13 corresponding to the rotation speed sensor 10 is provided on the clamping mechanism 2, and it is convenient to cooperate with the rotation speed sensor 10 to measure the number of revolutions of the impeller; the laser displacement sensor 11 and the rotation speed sensor 10 have the same data acquisition frequency and are respectively connected to the detection unit 12, so as to facilitate the transmission of the measurement data to the detection unit 12, so that the detection unit 12 can detect and analyze the eccentricity and ellipticity of the impeller, the eccentricity of the blade, the deformation degree of the blade profile and the uniformity of the blade distribution.

[0047] The positions to be tested here include the position to be tested 1 corresponding to the open loop part of the impeller (at Figure 1 The number is 001) and the impeller blade part corresponding to the test position 2 (in Figure 1 The middle label number is 002), and the position to be measured 1 and the position to be measured 2 both correspond to the circumference part of the circle.

[0048] When this system is used for detection, the speed sensor determines the number of revolutions of the impeller by detecting the position of the reflective sheet. The speed sensor signal is also used as a trigger signal for starting and ending data analysis. The speed sensor and the laser displacement sensor have the same data acquisition frequency (i.e., have equal data acquisition intervals). During synchronous acquisition, the speed sensor can determine the relative position of the laser displacement sensor acquisition point and the reflective sheet at any time, so that the position of the point to be measured can be calculated. Then, the eccentricity and ellipticity of the impeller, the eccentricity of the blade, the deformation of the blade profile, and the uniformity of the blade distribution are detected and analyzed through the relevant algorithms in the detection unit.

[0049] During specific implementation, the clamping mechanism 2 is rotatably arranged on the working platform 1 through a transmission mechanism; the transmission mechanism includes a motor 4 and a reduction gear box 5, and the motor 4 and the reduction gear box 5 are arranged below the working platform 1. The output shaft of the motor 4 is connected to the reduction gear box 5, and an axial hole is provided on the working platform 1, which passes through the upper and lower surfaces of the working platform 1 and corresponds to the transmission shaft of the reduction gear box 5. The transmission shaft of the reduction gear box 5 extends out of the axial hole of the working platform 1 and is connected to the center of the clamping mechanism 2, so that the motor 4 is started, thereby driving the clamping mechanism 2 to rotate, and then driving the impeller 3 to rotate.

[0050] During specific implementation, a bearing 6 is provided between the working platform 1 and the clamping mechanism 2 . The bearing 6 is sleeved on the transmission shaft of the reduction gear box 5 and is fixedly connected to the clamping mechanism 2 .

[0051] In a specific implementation, the clamping mechanism 2 is a three-claw clamp.

[0052] In specific implementation, a level meter 7 is provided on the work platform 1 , and leveling screws 8 are provided at the four corners of the work platform 1 , so that the leveling screws 8 can be adjusted by observing the level meter 7 to keep the work platform 1 in a horizontal state.

[0053] An impeller detection method is provided, which uses the above-mentioned impeller detection system to perform detection, marks the position of the impeller ring as the detection position 1, marks the position of the impeller blade as the detection position 2, and the circumferential direction corresponding to the detection position 1 and the detection position 2 has a plurality of detection points; specifically, the following steps are included:

[0054] S1: Place the laser displacement sensor at the position 1 to be measured. After the impeller speed is stable, start the detection unit to synchronously collect the distance from the laser displacement sensor to the position 1 to be measured and the impeller speed. The collected data is processed based on the 3σ principle, and then the eccentricity and ovality of the impeller are detected and analyzed.

[0055] S2: Repeat step S1 to perform multiple detection and analysis, and output the detection results;

[0056] S3: Place the laser displacement sensor at the position 2 to be measured. After the impeller speed is stable, start the detection unit to synchronously collect the distance from the laser displacement sensor to the position 2 to be measured and the impeller speed. The collected data is processed based on the 3σ principle, and then the blade eccentricity, blade profile deformation and blade distribution uniformity are detected and analyzed.

[0057] S4: Repeat step S4 to perform multiple detection and analysis and output the detection results.

[0058] Collecting data multiple times for detection and analysis can ensure the accuracy and effectiveness of the detection and analysis.

[0059] In specific implementation, the detection and analysis of step S1 and step S3 include the following steps:

[0060] (1) Calculate t i The distance R between the measured point and the rotation center at the measured position at the moment i and the impeller rotation angle θ i ;

[0061] R i =ll i

[0062]

[0063] Where: l is the distance between the laser displacement sensor and the rotation center;

[0064] l iis the distance between the laser displacement sensor and the position to be measured on the impeller;

[0065] t1 and t2 are the start and end time of data collection respectively;

[0066] n1 is the number of reflective sheet signals during the time period t2-t1;

[0067] (2) Establish a coordinate system with the impeller rotation center as the coordinate origin. The coordinates of any point to be measured at the measured position are (x i ,y i ), where x i =R i cosθ i ;y i =R i sinθ i The eccentricity e1 and ellipticity d of the impeller are calculated by fitting the circle equation and the ellipse equation by the least square method respectively; the blade profile is fitted to calculate the deformation B1 and unevenness C1 of the impeller blade, and the eccentricity e2 of the impeller blade is calculated by fitting the circle by the least square method.

[0068] In specific implementation, when calculating the impeller eccentricity, first establish the impeller fitting center coordinates (x c ,y c ) and the impeller rotation center deviation formula:

[0069] ming(R i ,θ i )=∑((x i -x c ) 2 +(y i -y c ) 2 -R 2 )

[0070] Where: R is the radius of the fitting circle.

[0071] Adjust x several times c ,y c and R values ​​make ming(R i ,θ i ) is the smallest, thus obtaining the fitting center coordinate (x c ,y c ), and then the impeller eccentricity e1 is calculated as:

[0072] In specific implementation, the calculation of the impeller ovality includes the following steps:

[0073] Based on the ellipse equation Ax i 2 +Bx i yi +Cy i 2 +Dx i +Ey i +F=0, adjust the values ​​of A, B, C, D, E and F, and change the coordinates of the point to be measured (x i ,y i ) into the ellipse equation, so that Ax i 2 +Bx i y i +Cy i 2 +Dx i +Ey i The value of +F approaches 0, thus obtaining the values ​​of A, B, C, D, E and F at this time.

[0074] Then the geometric center coordinates (x T ,y T ),in Thus we get the major and minor axes a and b of the ellipse: Then the ellipticity d is:

[0075] In practical applications, if the eccentricity and / or ovality of the impeller exceeds the set value, it indicates that the quality of the impeller is unqualified.

[0076] In the specific implementation, the calculation of the impeller blade eccentricity includes the following steps: taking the rotation center as the coordinate origin, fitting the impeller blade profile, and then determining n2 circles at a certain interval in the radial direction of the impeller, and each circle corresponds to a number of points to be measured, and using the least squares method to fit the circle to obtain the fitting center (x cm ,y cm ), then the impeller blade eccentricity e2 is:

[0077] This embodiment takes an impeller with 6 blades as an example, and obtains the impeller blade profile as follows: Figure 2 Then, in the radial direction of the impeller, three circles are determined at a certain interval, as shown in Figure 3 As shown, when calculating the blade eccentricity, the coordinates of the six test points of each circle on the blade are calculated in turn, and then the least squares method is used to fit the circle to obtain the fitting center coordinates of each circle, and the eccentricity of the blade where each circle is located is obtained (this method is consistent with the method for calculating the impeller eccentricity), and then the average eccentricity of the three measuring points is calculated to obtain the impeller blade eccentricity.

[0078] In specific implementation, the impeller blade deformation B1:

[0079]

[0080] Where: x i0 ,y i0 are the coordinates of the points to be measured on the blade profile (x i ,y i ) is the horizontal and vertical coordinates of the standard blade profile corresponding to the blade; k is the total number of points to be measured.

[0081] like Figure 4 As shown in the figure, the test profile is the profile of the blade to be tested, and the standard profile is the standard blade profile. When calculating, each blade can take several test points, and the corresponding blade deformation is the average deformation of each test point.

[0082] In the specific implementation, when analyzing the uneven distribution of blades, the rotation center is taken as the coordinate origin, and n3 circles are determined at a certain interval in the radial direction of the impeller, and each blade is numbered, marked as 1, 2, 3...j in sequence. Under the same radius, the distance between blade 2 and blade 1 is recorded as d1, the distance between blade 3 and blade 2 is recorded as d2, and the distance between blade 1 and blade j is recorded as d j ; Then the unevenness C1 of the impeller blade is:

[0083] The distance between two adjacent blades is calculated by calculating the coordinates of two points to be measured corresponding to the intersection of the circle and the corresponding two blade profiles.

[0084] Finally, it should be noted that the above embodiments of the present invention are only examples for illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. An impeller detection method, characterized in that: The detection is performed using an impeller detection system, the impeller detection system comprising a working platform, a clamping mechanism for clamping the impeller, the clamping mechanism being rotatably arranged on the working platform to rotate the impeller, a fixing column being vertically arranged on the working platform, a laser displacement sensor and a rotation speed sensor being arranged on the fixing column, the laser displacement sensor being used to measure the distance from the laser displacement sensor to the impeller position to be measured, a reflective sheet corresponding to the rotation speed sensor being arranged on the clamping mechanism, and being convenient for cooperating with the rotation speed sensor to measure the number of revolutions of the impeller; the laser displacement sensor and the rotation speed sensor having the same data acquisition frequency and being respectively connected to the detection unit; the impeller mouth ring position is marked as the position to be measured 1, the impeller blade position is marked as the position to be measured 2, and the circumferential directions corresponding to the position to be measured 1 and the position to be measured 2 both have a number of points to be measured; the specific steps include: S1: Place the laser displacement sensor at the position 1 to be measured. After the impeller speed is stable, start the detection unit to synchronously collect the distance from the laser displacement sensor to the position 1 to be measured and the impeller speed. The collected data is processed based on the 3σ principle, and then the eccentricity and ovality of the impeller are detected and analyzed. S2: Repeat step S1 to perform multiple detection and analysis, and output the detection results; S3: Place the laser displacement sensor at the position 2 to be measured. After the impeller speed is stable, start the detection unit to synchronously collect the distance from the laser displacement sensor to the position 2 to be measured and the impeller speed. The collected data is processed based on the 3σ principle, and then the blade eccentricity, blade profile deformation and blade distribution uniformity are detected and analyzed. S4: Repeat step S4 to perform multiple detection and analysis, and output the detection results; The detection and analysis of step S1 and step S3 include the following steps: (1) Calculate t i The distance R between the measured point and the rotation center at the measured position at the moment i and the impeller rotation angle θ i ; R i ＝l-l i Where: l is the distance between the laser displacement sensor and the rotation center; l i is the distance between the laser displacement sensor and the position to be measured on the impeller; t1 and t2 are the start and end time of data collection respectively; n1 is the number of reflective sheet signals during the time period t2-t1; (2) Establish a coordinate system with the impeller rotation center as the coordinate origin. The coordinates of any point to be measured at the measured position are (x i ,y i ), where x i =R i cosθ i ;y i =R i sinθ i , respectively using the least square method to fit the circle equation and the least square method to fit the ellipse equation to calculate the eccentricity e1 and ellipticity d of the impeller; fitting the blade profile, calculating the deformation B1 and unevenness C1 of the impeller blade, and using the least square method to fit the circle to calculate the eccentricity e2 of the impeller blade; Impeller blade deformation B1: Where: x i0 ,y i0 are the coordinates of the points to be measured on the blade profile (x i ,y i ) corresponding to the horizontal and vertical coordinates of the standard blade profile; k is the total number of points to be measured.

2. An impeller detection method according to claim 1, characterized in that: The clamping mechanism can be rotatably arranged on the working platform through the transmission mechanism; the transmission mechanism includes a motor and a reduction gear box, and the motor and the reduction gear box are arranged below the working platform. The motor output shaft is connected to the reduction gear box, and an axial hole that passes through the upper and lower surfaces of the working platform and corresponds to the transmission shaft of the reduction gear box is provided on the working platform. The transmission shaft of the reduction gear box extends out of the axial hole of the working platform and is connected to the center of the clamping mechanism, so that the motor starts, thereby driving the clamping mechanism to rotate, and then driving the impeller to rotate.

3. An impeller detection method according to claim 2, characterized in that: A bearing is provided between the working platform and the clamping mechanism. The bearing sleeve is arranged on the transmission shaft of the reduction gear box and is fixedly connected to the clamping mechanism. A spirit level is provided on the working platform, and leveling screws are respectively provided at the four corners of the working platform, so that the leveling screws can be adjusted by observing the spirit level to make the working platform in a horizontal state.

4. The impeller detection method according to claim 1, characterized in that: When calculating the impeller eccentricity, first establish the impeller fitting center coordinates (x c ,y c ) and the impeller rotation center deviation formula: min g(R i ,the i )=Σ((x i -x c ) 2 +(y i -y c ) 2 -R 2 ) Where: R is the radius of the fitting circle; Adjust x several times c ,y c and R values ​​such that min g(R i ,θ i ) is the smallest, thus obtaining the fitting center coordinate (x c ,y c ), and then the impeller eccentricity e1 is calculated as:

5. The impeller detection method according to claim 1, characterized in that: When calculating the impeller ovality, the following steps are involved: Based on the ellipse equation Ax i 2 +Bx i y i +Cy i 2 +Dx i +Ey i +F=0Adjust the values ​​of A, B, C, D, E and F, and change the coordinates of the point to be measured (x i ,y i ) into the ellipse equation, so that Ax i 2 +Bx i y i +Cy i 2 +Dx i +Ey i The value of +F approaches 0, thus obtaining the values ​​of A, B, C, D, E and F at this time; Then the geometric center coordinates (x T ,y T ),in Thus we get the major axis a and minor axis b of the ellipse: Then the ellipticity d is:

6. An impeller detection method according to claim 4, characterized in that: When calculating the eccentricity of the impeller blade, the following steps are included: taking the rotation center as the coordinate origin, in the radial direction of the impeller, n2 circles are determined at a certain interval, and each circle corresponds to a number of points to be measured, and the least squares method is used to fit the circle to obtain the fitting center (x cm ,y cm ), then the impeller blade eccentricity e2 is:

7. An impeller detection method according to claim 4, characterized in that: When analyzing the uneven distribution of blades, the rotation center is taken as the coordinate origin. In the radial direction of the impeller, n3 circles are determined at a certain interval and each blade is numbered, marked as 1, 2, 3...j in sequence. Under the same radius, the distance between blade 2 and blade 1 is recorded as d1, the distance between blade 3 and blade 2 is recorded as d2, and the distance between blade 1 and blade j is recorded as d j ; Then the unevenness C1 of the impeller blade is:

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