Fan outlet total temperature measuring point arrangement and test parameter correction method

Abstract

The application belongs to the technical field of engine state monitoring, and particularly relates to a fan outlet total temperature measuring point arrangement and test parameter correction method. The fan outlet total temperature measuring point arrangement method comprises the following steps: S1, determining the axial position of a total temperature measuring section; S2, determining a measuring point arrangement line of the total temperature measuring point on the total temperature measuring section, projecting the tail edge of the last stage stator blade onto the total temperature measuring section along the fan axial direction, and determining the measuring point arrangement line based on the relationship between the relative grid distance and the relative blade height; S3, obtaining the fan outlet total temperature field through a plurality of total temperature probes installed circumferentially on the fan casing, determining the average total temperature of the total temperature field, and simultaneously obtaining the temperature of each measuring point on the measuring point arrangement line; and S4, selecting the measuring point corresponding to the average total temperature on the measuring point arrangement line, and arranging a total temperature tube at the measuring point. The application can improve the determination efficiency of the fan outlet total temperature measuring point position selection scheme and improve the test accuracy.

Description

Technical Field

[0001] This application belongs to the field of engine condition monitoring technology, specifically relating to a method for arranging fan outlet total temperature measuring points and correcting test parameters. Background Technology

[0002] Aero engines are extremely precise machines. To improve their performance and design high-thrust, low-fuel-consumption high-performance engines, accurately obtaining the parameters of various engine sections is crucial for judging engine performance. The fan is a vital component of the turbofan engine's compression system. However, due to space limitations in the layout of fan outlet measuring points under engine conditions, only a limited number of measuring points can be arranged at finite angular locations. Because of the non-uniformity of the total temperature field at the fan outlet, directly arranging a limited number of measuring points will result in a significant error between the measured total temperature and the actual total temperature. Typically, to improve the accuracy of fan outlet total temperature field testing under limited measuring point conditions, numerous experiments are required to measure the total temperature field at the fan outlet and select a measuring point close to the average total temperature within the total temperature field. This method is costly and inefficient. Summary of the Invention

[0003] To address the aforementioned issues, this application provides a method for arranging total temperature measurement points at the fan outlet. This method can quickly identify a layout scheme for measurement points that approximates the average total temperature. Furthermore, for any arrangement of total temperature measurement points, this invention proposes a test parameter correction method based on the relationship between the measurement point location and the fan's total temperature field. This method can correct the total temperature test values ​​that deviate from the average total temperature measurement points.

[0004] The first aspect of this application provides a method for arranging total temperature measuring points at a fan outlet, mainly including:

[0005] Step S1: Determine the axial position of the total temperature measurement section at the fan outlet. The measurement section is located at a set distance behind the trailing edge of the last stage stator blade of the fan.

[0006] Step S2: Determine the measurement point layout line of the total temperature measurement points on the total temperature measurement cross section. Project the trailing edge of the last stage stator blade along the fan axis onto the total temperature measurement cross section, forming the measurement point layout line between two adjacent trailing edge projection lines. The ratio of the distance of the total temperature measurement point on the measurement point layout line from one of the trailing edge projection lines to the distance between the two trailing edge projection lines is the relative pitch w. The ratio of the distance of the total temperature measurement point from the bottom of the trailing edge projection line to the height of the trailing edge projection line is the relative blade height h. The measurement point layout line satisfies the following constraint relationship:

[0007] When the relative leaf height h is between 5% and 80%, w = 0.5 + (h - 0.05) / 15;

[0008] When the relative leaf height h is between 80% and 95%, w = 0.55 + (h - 0.8) × 3 / 4;

[0009] Step S3: Obtain the total temperature field at the fan outlet by installing multiple total temperature probes around the fan casing, determine the average total temperature of the total temperature field, and simultaneously obtain the temperature of each measuring point on the measuring point layout line.

[0010] Step S4: Select a measuring point on the measuring point layout line that corresponds to the average total temperature, and arrange the total temperature tube at the measuring point.

[0011] Preferably, in step S1, the set distance is 1.5 times the chord length of the last stage stator blade.

[0012] Preferably, step S2 further includes correcting the measurement point arrangement line to a straight line so that the variance of points with a relative leaf height h of more than 50% is minimized.

[0013] Preferably, in step S3, obtaining the total temperature field at the fan outlet includes:

[0014] Multiple total temperature probe mounting bases are arranged around the fan casing, and the total temperature is measured in batches at different circumferential positions. The total temperature field is obtained by combining the total temperature test results at each circumferential position.

[0015] Preferably, step S4 further includes:

[0016] When the selected measuring point corresponding to the average total temperature cannot be used to install the total temperature tube due to interference from other components, other alternative measuring points that are convenient for installing the total temperature tube are selected on the measuring point layout line, and the total temperature tube is installed at the alternative measuring point. The temperature of the alternative measuring point is corrected by the preset total temperature correction amount.

[0017] A second aspect of this application provides a method for correcting test parameters at a fan outlet total temperature measuring point, used to correct the temperature at the aforementioned replacement measuring point, the correction method comprising:

[0018] Step S1: Obtain the relative grid pitch w and relative blade height h of the replacement measurement point;

[0019] Step S2: Determine the total temperature correction δT:

[0020] δT=(t-1)*T 理论 ;

[0021] Among them, T 理论 Let t be the theoretical total temperature at the fan outlet under the current condition. For parameter t, when the relative pitch w is less than or equal to 20%, t = (c-1)*(w-0.1) / 0.1+1; otherwise, t = (c-1)*(0.55-w) / 0.35+1. For parameter c, when the relative blade height h is less than or equal to 50%, c = 1.0006; otherwise, c = -0.3522h. 3+0.7186h 2 -0.451h +1.0907;

[0022] Step S3: Correct the total temperature T based on the total temperature correction amount δT 修正 :

[0023] T 修正 =δT+T 测量 ;

[0024] Among them, T 测量 To replace the measured value of the measuring point.

[0025] This application can improve the efficiency of determining the location of the total temperature measurement point at the fan outlet and improve the accuracy of the test. This application corrects the total temperature test results based on the relative grid pitch between the measurement point and the trailing edge of the blade, so that the test results are closer to the average total temperature of the test section. Attached Figure Description

[0026] Figure 1 This is a flowchart of a preferred embodiment of the method for arranging total temperature measuring points at the fan outlet of this application.

[0027] Figure 2 This is a schematic diagram of the projection of the fan's final stage stator onto the measurement section. Detailed Implementation

[0028] 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. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0029] The first aspect of this application provides a method for arranging total temperature measuring points at the fan outlet, such as... Figure 1 As shown, it mainly includes:

[0030] Step S1: Determine the axial position of the total temperature measurement section at the fan outlet. The measurement section is located at a set distance behind the trailing edge of the last stage stator blade of the fan.

[0031] In this embodiment, the total airflow temperature remains constant after the fan outlet. Considering the stability of the flow field, the measurement section is located at a position no less than 1.5 times the chord length of the last-stage stator, provided the structural space allows. For example, in some optional embodiments, the set distance is 1.5 times the chord length of the last-stage stator blades.

[0032] Step S2: Determine the measurement point layout line of the total temperature measurement points on the total temperature measurement cross section. Project the trailing edge of the last stage stator blade along the fan axis onto the total temperature measurement cross section, and form the measurement point layout line between two adjacent trailing edge projection lines. The ratio of the distance of the total temperature measurement point on the measurement point layout line from one of the trailing edge projection lines to the distance between the two trailing edge projection lines is the relative grid pitch w. The ratio of the distance of the total temperature measurement point from the bottom of the trailing edge projection line to the height of the trailing edge projection line is the relative blade height h.

[0033] refer to Figure 2 After selecting the axial test section, the trailing edge of the last stage stator blade of the fan is projected axially onto the measurement section. Let the relative blade height be h and the relative grid pitch be w. The algorithm for the relative grid pitch of the circumferential position of the measuring point at different relative blade heights is as follows:

[0034] When the relative leaf height h is between 5% and 80%, w = 0.5 + (h - 0.05) / 15;

[0035] When the relative leaf height h is between 80% and 95%, w = 0.55 + (h - 0.8) × 3 / 4.

[0036] For areas with less than 5% and greater than 95% of the total temperature, the measurement error is relatively large due to the influence of boundary layer and other factors, and it is not recommended to set up measurement points in these areas.

[0037] In some alternative implementations, step S2 further includes correcting the measurement point layout line to a straight line so that the variance of points with a relative leaf height h of more than 50% is minimized.

[0038] In this embodiment, as can be seen from the above algorithm, the determined measuring points may not be on a straight line. However, in actual operation, for reasons such as ease of installation, the total heating pipe is a straight pipe, and the measuring points need to be arranged in a straight line along the radial direction. At this time, the measuring points will deviate from the value calculated in the second step. If this happens, it is possible to prioritize ensuring that 50% of the measuring points above the relative blade height are near the position calculated by the above method. That is, the dispersion of each measuring point is controlled by means of variance or standard deviation.

[0039] Step S3: Obtain the total temperature field at the fan outlet by installing multiple total temperature probes around the fan casing, determine the average total temperature of the total temperature field, and simultaneously obtain the temperature of each measuring point on the measuring point layout line.

[0040] Due to structural space limitations, the actual circumferential positions where total temperature measurement points can be arranged in the engine are limited. In order to obtain the accurate total temperature distribution at the fan outlet under the condition of the whole machine, and at the same time reduce the influence of the probe on the total temperature field, in some optional embodiments, obtaining the total temperature field at the fan outlet includes: arranging multiple total temperature probe mounting seats around the fan casing, measuring the total temperature in batches at different circumferential positions, and combining the total temperature test results at each circumferential position to obtain the total temperature field.

[0041] Step S4: Select a measuring point on the measuring point layout line that corresponds to the average total temperature, and arrange the total temperature tube at the measuring point.

[0042] In some alternative implementations, when the total temperature tube cannot be placed at the measurement point corresponding to the average total temperature due to interference from other components, other alternative measurement points that are convenient for placing the total temperature tube are selected on the measurement point layout line, and the total temperature tube is placed at the alternative measurement point. The temperature of the alternative measurement point is corrected by a preset total temperature correction amount.

[0043] Understandably, due to the limited space for test layout under whole-machine conditions, sometimes the locations determined by the above method cannot be used to arrange measurement points. In this case, the measured total temperature will have a certain difference from the average total temperature of that cross section. Through numerical calculation and statistical analysis of test data, a correction algorithm is derived and preset in the engine control system. During the whole-machine test of the engine, the preset correction algorithm provides flow field correction for the total temperature at different test locations.

[0044] Based on the above embodiments, a second aspect of this application provides a method for correcting test parameters of a fan outlet total temperature measuring point, used to correct the temperature of a replacement measuring point, the correction method comprising:

[0045] Step S1: Obtain the relative grid pitch w and relative blade height h of the replacement measurement point;

[0046] Step S2: Determine the total temperature correction δT:

[0047] δT=(t-1)*T 理论 ;

[0048] Among them, T 理论 Let t be the theoretical total temperature at the fan outlet under the current condition. For parameter t, when the relative pitch w is less than or equal to 20%, t = (c-1)*(w-0.1) / 0.1+1; otherwise, t = (c-1)*(0.55-w) / 0.35+1. For parameter c, when the relative blade height h is less than or equal to 50%, c = 1.0006; otherwise, c = -0.3522h. 3 +0.7186h 2 -0.451h +1.0907;

[0049] Step S3: Correct the total temperature T based on the total temperature correction amount δT 修正 :

[0050] T 修正 =δT+T 测量 ;

[0051] Among them, T 测量 To replace the measured value of the measuring point.

[0052] This application can improve the efficiency of determining the location of the total temperature measurement point at the fan outlet and improve the accuracy of the test. This application corrects the total temperature test results based on the relative grid pitch between the measurement point and the trailing edge of the blade, so that the test results are closer to the average total temperature of the test section.

[0053] Although this application has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A method for arranging total temperature measuring points at a fan outlet, characterized in that, include: Step S1: Determine the axial position of the total temperature measurement section at the fan outlet. The measurement section is located at a set distance behind the trailing edge of the last stage stator blade of the fan. Step S2: Determine the measurement point layout line of the total temperature measurement points on the total temperature measurement cross section. Project the trailing edge of the last stage stator blade along the fan axis onto the total temperature measurement cross section, forming the measurement point layout line between two adjacent trailing edge projection lines. The ratio of the distance of the total temperature measurement point on the measurement point layout line from one of the trailing edge projection lines to the distance between the two trailing edge projection lines is the relative pitch w. The ratio of the distance of the total temperature measurement point from the bottom of the trailing edge projection line to the height of the trailing edge projection line is the relative blade height h. The measurement point layout line satisfies the following constraint relationship: When the relative leaf height h is between 5% and 80%, w = 0.5 + (h - 0.05) / 15; When the relative leaf height h is between 80% and 95%, w = 0.55 + (h - 0.8) × 3 / 4; Step S3: Obtain the total temperature field at the fan outlet by installing multiple total temperature probes around the fan casing, determine the average total temperature of the total temperature field, and simultaneously obtain the temperature of each measuring point on the measuring point layout line. Step S4: Select a measuring point on the measuring point layout line that corresponds to the average total temperature, and arrange the total temperature tube at the measuring point.

2. The method for arranging total temperature measuring points at the fan outlet as described in claim 1, characterized in that, In step S1, the set distance is 1.5 times the chord length of the last stage stator blade.

3. The method for arranging total temperature measuring points at the fan outlet as described in claim 1, characterized in that, Step S2 further includes correcting the measurement point layout line to a straight line so that the variance of points with a relative leaf height h of more than 50% is minimized.

4. The method for arranging total temperature measuring points at the fan outlet as described in claim 1, characterized in that, In step S3, obtaining the total temperature field at the fan outlet includes: Multiple total temperature probe mounting bases are arranged around the fan casing, and the total temperature is measured in batches at different circumferential positions. The total temperature field is obtained by combining the total temperature test results at each circumferential position.

5. The method for arranging total temperature measuring points at the fan outlet as described in claim 1, characterized in that, Step S4 further includes: When the selected measuring point corresponding to the average total temperature cannot be used to install the total temperature tube due to interference from other components, other alternative measuring points that are convenient for installing the total temperature tube are selected on the measuring point layout line, and the total temperature tube is installed at the alternative measuring point. The temperature of the alternative measuring point is corrected by the preset total temperature correction amount.

Images