Infrared testing system and testing method for tail jet of mobile turntable type small engine

Abstract

The present application relates to a kind of mobile rotary table type small engine tail jet's infrared test system, including the engine or nozzle being arranged on the rotating platform of rotary table system, rotary table system is used to drive the engine or nozzle to be measured to carry out 0~360 ° rotation in horizontal plane;It also includes thermal imager and control system;When the device to be measured is nozzle, then also include adjustable outer channel cooling air blower and outer channel gas collecting pipeline for providing.This application also provides the test method that the system can be realized.This application solves the key problems that traditional large fixed test bed is high in cost, not flexible, and existing ground test means cannot consider multi-angle automatic measurement, high-precision data acquisition and convenient deployment, realizes the highly efficient infrared radiation characteristic test system and method that height integration mobility, full-angle automatic measurement, extensive test function, high-precision data guarantee and operation safety automation are integrated.

Description

Technical Field

[0001] This invention relates to an engine testing apparatus and method. Background Technology

[0002] Infrared detection technology has become a core element in the modern aviation equipment's stealth and anti-stealth competition. Infrared radiation characteristic data of aero engines, especially their exhaust systems, are the primary input for target characteristic modeling, stealth design, and verification, and must be obtained through high-precision experimental measurements.

[0003] However, the current testing system is still mainly based on large fixed test stands or high-altitude simulation chambers. The construction cost of a single facility is often hundreds of millions of yuan, the cycle is measured in years, and the operating cost is high. More importantly, the relative position of the test stand and the optical path is fixed, and it is impossible to continuously change the detection angle. It is difficult to obtain the omnidirectional radiation distribution of the engine at one time, resulting in long data mosaic cycle and high uncertainty.

[0004] Meanwhile, existing ground-based infrared testing devices generally suffer from the following bottlenecks: 1. Fixed viewing angle: The engine azimuth angle adjustment is discrete, the repeatability positioning accuracy is poor, the spatial sampling is sparse, and it is impossible to draw a high-fidelity three-dimensional radiation isosurface; 2. Low integration: Power, air supply, measurement and control, and optical equipment are scattered, making them inconvenient to move and deploy, and difficult to conduct tests in the field or in simple sites.

[0005] 3. Significant background interference: Insufficient suppression of ambient radiation and stray light; low signal segments (such as cryogenic nozzles and low-emission coatings) are easily swallowed up by background noise, resulting in a dynamic range loss of 2–3 orders of magnitude.

[0006] 4. Data distortion: The lack of a high-speed acquisition and real-time correction link for wide dynamic range infrared signals causes the nonlinear error of the traditional average filtering mode to surge at high gain levels, resulting in measurement results deviating from the true value.

[0007] Therefore, for the fundamental innovation research of small aero-engine nozzles, low-emission coatings, etc., there is an urgent need for a low-cost ground measurement alternative that can be moved, rotated, and measured accurately. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a mobile turntable infrared testing system and method for small engine exhaust nozzles that can achieve high integration, mobile deployment, and multi-angle, automated, and high-precision infrared radiation characteristic testing of small real engines or scaled-down models.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: an infrared testing system and method for the exhaust nozzle of a small mobile turntable engine, including an engine set on a rotating platform of the turntable system, wherein the engine is used as the engine to be tested, and the turntable system is used to drive the engine to be tested to rotate 0 to 360° in the horizontal plane. A thermal imager, with its thermal imaging lens positioned at the exhaust nozzle outlet of the engine under test, is used to detect the temperature distribution and infrared radiation distribution of the exhaust flame of the engine under test. The thermal imager includes at least one medium-wave thermal imager and at least one long-wave thermal imager, used to detect temperature distribution under different response infrared radiation wavelengths; Control systems, including industrial PCs and remote control computers; The remote control computer communicates with the rotary platform of the turntable system, the blower, the ECU of the engine under test, the thermal imager, and the industrial control computer via Ethernet or serial port. The remote control computer is used to control the rotation angle of the rotating platform to drive the engine under test, thereby adjusting the azimuth angle of the engine under test relative to the thermal imager; at the same time, it controls the operation of the engine under test and synchronously triggers the thermal imager and the industrial control computer to collect data. Simultaneously, the industrial control computer synchronously collects temperature and pressure signals from thermocouples and pressure sensors installed in the engine's internal and external inlets, and receives the digital image stream from the thermal imager. It also includes a generator, which is electrically connected to the thermal imager, rotating platform, industrial control computer and remote control computer to supply power to each component.

[0010] Furthermore, it also includes a black tarpaulin and a black background baffle. The black tarpaulin is placed on the ground between the thermal imager and the turntable base, and the black background baffle is supported and shielded at the exhaust nozzle outlet of the engine under test for background purification, so that the thermal imager can acquire high-fidelity images.

[0011] Furthermore, it also includes a nozzle, which is coaxially positioned behind the engine's exhaust nozzle. In this case, the engine provides a high-temperature combustion gas source for the nozzle's inner duct. The nozzle is the nozzle to be tested, and the turntable system is used to drive the nozzle to be tested to rotate 0 to 360° in the horizontal plane. The blower's outlet is connected to the outer bypass of the nozzle under test via an outer bypass air collection pipe to provide adjustable outer bypass cooling air. A thermal imager, with its thermal imaging lens positioned at the nozzle exit to detect the temperature distribution and infrared radiation distribution of the nozzle wall and exhaust plume. The remote control computer is used to control the rotation angle of the nozzle under test driven by the rotating platform, thereby adjusting the azimuth angle of the nozzle relative to the thermal imager; at the same time, it controls the air supply frequency of the blower, that is, adjusts the cooling air flow of the outer bypass of the nozzle under test; it controls the operation of the engine and simultaneously triggers the thermal imager and industrial control computer to collect data; simultaneously, the industrial control computer synchronously collects temperature and pressure signals from the K-type thermocouples and pressure sensors installed in the inner and outer bypass inlets of the nozzle, and receives the digital image stream from the thermal imager; It also includes a generator, which is electrically connected to the thermal imager, blower, rotating platform, industrial control computer and remote control computer to supply power to each component.

[0012] Furthermore, it also includes a black tarpaulin and a black background baffle. The black tarpaulin is placed on the ground between the thermal imager and the turntable base, and the black background baffle is supported and shielded at the nozzle exit of the nozzle to be tested for background purification, so that the thermal imager can acquire high-fidelity images.

[0013] Furthermore, the mid-wave thermal imager has a response infrared radiation wavelength of 3-5 μm, and the long-wave thermal imager has a response infrared radiation wavelength of 8-14 μm, and infrared thermal images are acquired at a distance of 25-45 m from the tail nozzle to be measured.

[0014] Furthermore, the turntable system includes a turntable base, with casters and adjustable feet installed at the bottom of the turntable base for easy movement, leveling, and locking; the industrial control computer is installed inside the turntable base. The rotating platform is mounted on the turntable base. The engine and nozzle to be tested are fixedly mounted on the rotating platform through the support bracket. The turntable base has a built-in servo motor and worm gear reducer, which are controlled and driven by a remote control computer. The servo motor and worm gear reducer are used to control the rotation angle, which is fed back by a high-precision encoder, and the positioning accuracy is higher than 0.1°.

[0015] This invention also provides an infrared testing method implemented by an infrared testing system for the exhaust nozzle of a small mobile turntable engine, specifically including the following steps: Step 1: Install the engine to be tested on the rotating platform of the turntable system, control the engine operation using a remote control computer, and lay down a black tarpaulin and a black background baffle. Step 2: Turn off the ambient light, control the rotating platform to rotate and adjust the azimuth angle between the engine exhaust nozzle and the thermal imager. At the same time, under different azimuth angle conditions, use the long-wave thermal imager to collect temperature distribution data and generate long-wave visual thermal images. Use the medium-wave thermal imager to repeatedly collect temperature distribution data in different temperature measurement ranges and generate multiple medium-wave visual thermal images. Step 3: Select medium-wave and long-wave visualized thermal images where the visible length of the exhaust jet is not less than 10 times the engine turbine outlet diameter, and the radiance at the edge of the medium-wave and long-wave visualized thermal images is not less than 110% of the average radiance of the background. These are considered valid medium-wave and long-wave visualized thermal images, and the corresponding temperature distribution data are considered valid data. This yields the medium-wave and long-wave radiation intensity I of the engine and background under test. 1中波 and I 1长波 ; Step 4: Remove the engine to be tested and repeat the process in Step 2 to collect the mid-wave and long-wave radiation intensity I in the full field of view background. 2中波 and I 2长波 At this point, the medium-wave and long-wave radiation intensities I of the engine under test can be calculated according to the formula. 中波 and I 长波 The specific formula is as follows: I 中波 = I 1中波 - I 2中波 ; I 长波 = I 1长波 - I 2长波 .

[0016] Furthermore, in step one, The preset angle interval is at least 5°, and the platform is rotated step by step. For each angle, the industrial control computer receives the digital image stream from the thermal imager to achieve a comprehensive test of the azimuth angle, and the distribution of infrared radiation characteristics with azimuth angle is obtained through the comprehensive test. Among them, infrared radiation characteristics include temperature distribution, infrared radiance, and integrated radiation intensity; Simultaneously, in step two, the maximum radiance value of each image pixel is determined by a remotely controlled computer-controlled medium-wave thermal imager. Temperature distribution data is collected in four temperature ranges: 0-40℃, 30-120℃, 110-300℃, and 280-650℃, generating a medium-wave visualized thermal image. For each pixel in the medium-wave visualized thermal image, the maximum radiance value in different temperature measurement ranges is cross-compared and selected as the true value, thereby reconstructing a complete, high dynamic range medium-wave radiance image to solve the measurement distortion problem caused by the temperature radiation at the engine's exhaust nozzle exceeding the linear range of a single interval.

[0017] This invention also provides an infrared testing method implemented by an infrared testing system for the exhaust nozzle of a small mobile turntable engine, specifically including the following steps: Step 1: Install the nozzle to be tested on the rotating platform of the turntable system. Use a remote control computer to control the engine to provide a high-temperature combustion gas source for the inner duct of the nozzle to be tested, and at the same time control the blower to provide cooling air for the outer duct of the nozzle. Meanwhile, lay out a black tarpaulin and a black background baffle. Step 2: Turn off the ambient light, control the rotating platform to rotate and adjust the azimuth angle between the nozzle tail nozzle and the thermal imager. At the same time, under different azimuth angle conditions, use the long-wave thermal imager to collect temperature distribution data and generate long-wave visual thermal images. Use the medium-wave thermal imager to repeatedly collect temperature distribution data in different temperature measurement ranges and generate multiple medium-wave visual thermal images. Step 3: Select mid-wave and long-wave visualized thermal images where the visible length of the exhaust jet is not less than 10 times the engine turbine outlet diameter, and the radiance at the edge of the mid-wave and long-wave visualized thermal images is not less than 110% of the average radiance of the background. These are considered valid mid-wave and long-wave visualized thermal images, and the corresponding temperature distribution data are considered valid data. This yields the mid-wave and long-wave radiation intensity I of the nozzle and background to be measured. 1中波 and I 1长波 ; Step 4: Remove the nozzle to be tested and repeat the process in Step 2 to collect the mid-wave and long-wave radiation intensity I in the full field of view background. 2中波 and I 2长波 At this point, the medium-wave and long-wave radiation intensities I of the nozzle itself can be calculated according to the formula. 中波 and I 长波 The specific formula is as follows: I 中波 = I 1中波 - I 2中波 ; I 长波 = I 1长波 - I 2长波 .

[0018] Furthermore, in step one: The preset angle interval is at least 5°, and the platform is rotated step by step. For each angle, the industrial control computer receives the digital image stream from the thermal imager to achieve a comprehensive test of the azimuth angle, and the distribution of infrared radiation characteristics with azimuth angle is obtained through the comprehensive test. Among them, infrared radiation characteristics include temperature distribution, infrared radiance, and integrated radiation intensity; Simultaneously, in step two, the maximum radiance value of each image pixel is controlled by a remote control computer to collect temperature distribution data in four temperature ranges: 0-40℃, 30-120℃, 110-300℃, and 280-650℃, generating a mid-wave visualized thermal image. For each pixel in the mid-wave visualized thermal image, the maximum radiance value in different temperature measurement ranges is cross-compared and selected as the true value, thereby reconstructing a complete, high dynamic range mid-wave radiance image to solve the measurement distortion problem caused by the temperature radiation at the nozzle tail nozzle exceeding the linear range of a single interval.

[0019] The beneficial effects of this invention are: This invention solves the key problems of high cost and inflexibility of traditional large fixed test benches, and the inability of existing ground testing methods to simultaneously achieve multi-angle automatic measurement, high-precision data acquisition and convenient deployment. It realizes a highly efficient infrared radiation characteristic testing system and method that integrates high-integration mobility, full-angle automatic measurement, extensive testing functions, high-precision data protection and automated operation safety. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall layout of the testing system of the present invention; Figure 2 This is a flowchart of the experimental operation of an embodiment of the present invention.

[0021] The labels in the diagram are as follows: 1-Turntable system, 2-Engine, 3-Nozzle, 4-External bypass air collection pipeline, 5-Blower, 6-Diesel generator, 7-Medium wave thermal imager, 8-Long wave thermal imager, 9-Black background baffle, 10-Black tarpaulin, 11-Control and data acquisition industrial computer, 12-Remote control computer. Detailed Implementation

[0022] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0023] To achieve the above objectives, the present invention provides the following specific embodiments: Example 1: As Figure 1 As shown, an infrared testing system and method for the exhaust nozzle of a small mobile turntable engine includes an engine 2 set on a rotating platform of a turntable system 1. At this time, the engine 2 is the engine to be tested, and the turntable system 1 is used to drive the engine to be tested to rotate 0 to 360° in the horizontal plane. A thermal imager, with its thermal imaging lens positioned at the exhaust nozzle outlet of the engine 2 under test, is used to detect the temperature distribution and infrared radiation distribution of the exhaust flame of the engine 2 under test. The thermal imager includes at least one medium-wave thermal imager 7 and at least one long-wave thermal imager 8, used to detect temperature distribution under different response infrared radiation wavelengths; The control system includes an industrial computer 11 and a remote control computer 12; The remote control computer 12 communicates with the rotating platform of the turntable system 1, the blower 5, the control unit ECU of the engine under test 2, the thermal imager, and the industrial control computer 11 via Ethernet or serial port. The remote control computer 12 is used to control the rotation angle of the rotating platform to drive the engine 2 under test, thereby adjusting the azimuth angle of the engine 2 under test relative to the thermal imager; at the same time, it controls the operation of the engine 2 under test and synchronously triggers the thermal imager and the industrial control computer 11 to collect data. Simultaneously, the industrial control computer 11 synchronously collects temperature and pressure signals from thermocouples and pressure sensors installed in the inner and outer ducts of the engine 2, and receives the digital image stream from the thermal imager. It also includes a generator 6, which is electrically connected to the thermal imager, the rotating platform, the industrial control computer 11 and the remote control computer 12, respectively, to supply power to each component.

[0024] It also includes a black tarpaulin and a black background baffle. The black tarpaulin is placed on the ground between the thermal imager and the turntable base, and the black background baffle is supported and shielded at the exhaust nozzle outlet of the engine 2 under test for background purification, so that the thermal imager can acquire high-fidelity images.

[0025] The mid-wave thermal imager 7 has a response infrared radiation wavelength of 3-5μm, and the long-wave thermal imager 8 has a response infrared radiation wavelength of 8-14μm. Infrared thermal images are acquired at a distance of 25-45m from the tail nozzle to be measured.

[0026] Example 2: Same as Example 1, except that it also includes a nozzle 3. The nozzle 3 is coaxially arranged behind the tail nozzle of the engine 2. In this case, the engine 2 provides a high-temperature gas source for the inner channel of the nozzle 3. The nozzle 3 is the nozzle to be tested. The turntable system 1 is used to drive the nozzle 3 to be tested to rotate 0 to 360° in the horizontal plane. The air outlet of the blower 5 is connected to the outer bypass of the nozzle 3 to be tested through the outer bypass air collection pipe 4, which is used to provide adjustable outer bypass cooling air. A thermal imager, with its thermal imaging lens positioned at the outlet of the nozzle 3 to be tested, is used to detect the temperature distribution and infrared radiation distribution of the nozzle wall and exhaust flame of the nozzle 3 to be tested. The remote control computer 12 is used to control the rotation angle of the nozzle 3 under test driven by the rotating platform, thereby adjusting the azimuth angle of the nozzle 3 relative to the thermal imager; at the same time, it controls the air supply frequency of the blower 5, that is, adjusts the cooling air flow of the outer bypass of the nozzle 3 under test; controls the operation of the engine 2, and synchronously triggers the thermal imager and the industrial control computer 11 to collect data; simultaneously, the industrial control computer 11 synchronously collects the temperature and pressure signals from the K-type thermocouples and pressure sensors installed in the inner and outer bypass inlets of the nozzle 3, and receives the digital image stream from the thermal imager; It also includes a generator 6, which is electrically connected to the thermal imager, blower 5, rotating platform, industrial control computer 11 and remote control computer 12 respectively, and is used to supply power to each component.

[0027] It also includes a black tarpaulin and a black background baffle. The black tarpaulin is placed on the ground between the thermal imager and the turntable base, and the black background baffle is supported and shielded at the nozzle outlet of the nozzle 3 to be tested for background purification, so that the thermal imager can acquire high-fidelity images.

[0028] The mid-wave thermal imager 7 has a response infrared radiation wavelength of 3-5μm, and the long-wave thermal imager 8 has a response infrared radiation wavelength of 8-14μm. Infrared thermal images are acquired at a distance of 25-45m from the tail nozzle to be measured.

[0029] Furthermore, the turntable system 1 includes a turntable base, with casters and adjustable feet installed at the bottom of the turntable base for easy movement, leveling, and locking. The industrial control computer 11 is installed inside the turntable base. The rotating platform is mounted on the turntable base. The engine 2 and nozzle 3 to be tested are fixedly mounted on the rotating platform through the bearing mounting bracket. The turntable base has a built-in servo motor and worm gear reducer, which are controlled and driven by the remote control computer 12. The servo motor and worm gear reducer are used to control the rotation angle, which is fed back by a high-precision encoder, and the positioning accuracy is higher than 0.1°.

[0030] Example 3: The present invention also provides an infrared testing method implemented by the infrared testing system for the exhaust nozzle of a small mobile turntable as in Example 1, specifically including the following steps: Step 1: Install the engine 2 to be tested on the rotating platform of the turntable system 1, control the operation of the engine 2 using the remote control computer 12, and lay out a black tarpaulin and a black background baffle. Step 2: Turn off the ambient light, control the rotating platform to rotate and adjust the azimuth angle between the exhaust nozzle of engine 2 and the thermal imager. At the same time, under different azimuth angle conditions, use the long-wave thermal imager 8 to collect temperature distribution data and generate long-wave visual thermal images. Use the medium-wave thermal imager 7 to repeatedly collect temperature distribution data in different temperature measurement ranges and generate multiple medium-wave visual thermal images. Step 3: Select medium-wave and long-wave visualized thermal images where the visible length of the exhaust jet is not less than 10 times the engine turbine outlet diameter, and the radiance at the edge of the medium-wave and long-wave visualized thermal images is not less than 110% of the average radiance of the background. These are considered valid medium-wave and long-wave visualized thermal images, and the corresponding temperature distribution data are considered valid data. This yields the medium-wave and long-wave radiation intensities I of the engine 2 under test and the background. 1中波 and I 1长波 ; Step 4: Remove the engine 2 to be tested, and repeat the process in Step 2 to collect the mid-wave and long-wave radiation intensity I of the full field of view background. 2中波 and I 2长波 At this point, the medium-wave and long-wave radiation intensities I of the engine 2 under test can be calculated according to the formula. 中波 and I长波 The specific formula is as follows: I 中波 = I 1中波 - I 2中波 ; I 长波 = I 1长波 - I 2长波 .

[0031] In step one, The preset angle interval is at least 5°, and the platform is rotated step by step. For each angle, the industrial control computer 11 receives the digital image stream from the thermal imager to achieve a comprehensive test of the azimuth angle, and obtain the distribution of infrared radiation characteristics with azimuth angle through the comprehensive test. Among them, infrared radiation characteristics include temperature distribution, infrared radiance, and integrated radiation intensity; Simultaneously, in step two, the maximum radiance value of each image pixel is controlled by the remote control computer 12 to collect temperature distribution data in four temperature ranges: 0-40℃, 30-120℃, 110-300℃, and 280-650℃, respectively, generating a medium-wave visualized thermal image. For each pixel of the medium-wave visualized thermal image, the maximum radiance value of different temperature measurement ranges is cross-compared and selected as the true value, thereby reconstructing a complete medium-wave radiance image with a high dynamic range. This solves the measurement distortion problem caused by the temperature radiation at the tail nozzle of engine 2 exceeding the linear range of a single interval.

[0032] Example 4: The present invention also provides an infrared testing method implemented by the infrared testing system for the exhaust nozzle of a small engine with a movable turntable as in Example 2, specifically including the following steps: Step 1: Install the nozzle 3 to be tested on the rotating platform of the turntable system 1. Use the remote control computer 12 to control the engine 2 to provide a high-temperature gas source for the inner duct of the nozzle 3 to be tested, and at the same time control the blower 5 to provide cooling air for the outer duct of the nozzle 3; at the same time, lay out a black tarpaulin and a black background baffle. Step 2: Turn off the ambient light, control the rotating platform to rotate and adjust the azimuth angle between the tail nozzle of nozzle 3 and the thermal imager. At the same time, under different azimuth angle conditions, use the long-wave thermal imager 8 to collect temperature distribution data and generate long-wave visual thermal images. Use the medium-wave thermal imager 7 to repeatedly collect temperature distribution data in different temperature measurement ranges and generate multiple medium-wave visual thermal images. Step 3: Select mid-wave and long-wave visualized thermal images containing exhaust jets with a visible length of no less than 10 times the engine turbine outlet diameter, and where the radiance at the edges of the mid-wave and long-wave visualized thermal images is no less than 110% of the average radiance of the background. These are considered valid mid-wave and long-wave visualized thermal images, and the corresponding temperature distribution data are considered valid data. This yields the mid-wave and long-wave radiation intensities I of the nozzle 3 to be measured and the background. 1中波 and I 1长波 ; Step 4: Remove nozzle 3 from the test area and repeat the process in Step 2 to collect the mid-wave and long-wave radiation intensity I in the full field of view background. 2中波 and I 2长波 At this point, the medium-wave and long-wave radiation intensities I of the nozzle 3 to be tested are calculated according to the formula. 中波 and I 长波 The specific formula is as follows: I 中波 = I 1中波 - I 2中波 ; I 长波 = I 1长波 - I 2长波 .

[0033] In step one: The preset angle interval is at least 5°, and the platform is rotated step by step. For each angle, the industrial control computer 11 receives the digital image stream from the thermal imager to achieve a comprehensive test of the azimuth angle, and obtain the distribution of infrared radiation characteristics with azimuth angle through the comprehensive test. Among them, infrared radiation characteristics include temperature distribution, infrared radiance, and integrated radiation intensity; Simultaneously, in step two, the maximum radiance value of each image pixel is controlled by the remote control computer 12 to collect temperature distribution data in four temperature ranges: 0-40℃, 30-120℃, 110-300℃, and 280-650℃, respectively, generating a medium-wave visualized thermal image. For each pixel of the medium-wave visualized thermal image, the maximum radiance value of different temperature measurement ranges is cross-compared and selected as the true value, thereby reconstructing a complete medium-wave radiance image with a high dynamic range. This solves the measurement distortion problem caused by the temperature radiation at the tail nozzle of the nozzle 3 exceeding the linear range of a single interval.

[0034] The invention also includes temperature and pressure signals collected by K-type thermocouples and pressure sensors, which are the total pressure and total temperature parameters. These parameters are only used to observe the state of the engine and the state of the airflow at the nozzle inlet.

[0035] like Figure 1 , Figure 2 As shown, to further illustrate the technical solution and technical effects of the present invention, the following specific examples are provided: Specific Example 1 Reference Figure 1 This specific example provides an infrared testing system and method for a mobile turntable-type small engine exhaust nozzle, specifically used to measure the infrared radiation characteristics of a certain scaled-down nozzle model.

[0036] The system mainly includes: Turntable System 1: Equipped with casters and adjustable feet at the bottom for easy movement, leveling, and locking. The turntable platform supports the mounting bracket for fixing the nozzle test specimen 3. The turntable incorporates a servo motor and worm gear reducer, driven by the control system, enabling the test specimen to rotate precisely 0-360° in the horizontal plane. The rotation angle is fed back by a high-precision encoder, with a positioning accuracy better than 0.1°. In this specific example, the test azimuth angle range is set from 0° tail-head to 90° lateral, with 5° intervals, for a total of 19 measuring points.

[0037] Power and air supply module: Includes a PTE-450A2 micro turbojet engine 2 (maximum thrust 45kgf), serving as a high-temperature gas source. Its exhaust nozzle is connected to the inner inlet flange of the nozzle test piece 3 via a high-temperature resistant metal bellows. A B75-10 single-stage high-speed centrifugal air-suspended blower 5, with its speed regulated by a frequency converter (maximum 29800rpm), provides adjustable cooling air for the outer bypass, which is connected to the outer bypass inlet of the test piece via the outer bypass air collection pipe 4 (containing a flow equalization device). A 100kW diesel generator 6 supplies power to the entire system.

[0038] The infrared detection and acquisition module includes an IRMC-615MW mid-wave thermal imager 7 (operating wavelength 3-5μm) and a HiNet-640 long-wave thermal imager 8 (operating wavelength 8-14μm), both mounted side-by-side on a heavy-duty tripod. The lens axis is on the same horizontal plane as the turntable rotation axis, 29.7 meters from the tail of the test piece. The data acquisition system uses an industrial computer 11 composed of an NI PCI-1713U acquisition card and an ADAM-3968 terminal board. Programmed using LabVIEW 2017 software, it synchronously acquires temperature and pressure signals from K-type thermocouples and pressure sensors with a range of -20~60kPa installed at the inlets of the inner and outer ducts, and receives digital image streams from the thermal imagers.

[0039] Control system: The core is a remote control computer 12 isolated from the Internet. It controls the rotation angle of the turntable 1, the frequency converter of the blower 5, and the ECU of the turbojet engine 2 through Ethernet and serial communication, and simultaneously triggers two thermal imagers 7 and 8 and the industrial control computer 11 to start data acquisition.

[0040] Background purification device: A large area of ​​black matte tarpaulin 10 is laid on the ground behind and on both sides of the turntable 1. Within the field of view of thermal imagers 7 and 8, a metal background baffle 9 with a black matte paint coating is erected at an angle behind and to the side rear of the test specimen to cover the complex ground and distant view.

[0041] Data processing unit: The software module is integrated into the industrial control computer 11 and the remote computer 12, and has the following functions: background removal of thermal images, effective area segmentation of test specimens, time averaging of multiple frames, and calculation of integrated radiance and radiance intensity based on pixel size and distance. Specifically, for the mid-wave thermal imager 7, the software controls it to collect data in four temperature ranges: "0-40℃", "30-120℃", "110-300℃", and "280-650℃", and selects the maximum effective radiance value of each pixel through a fusion algorithm.

[0042] The method and process for using this system for testing are as follows: Figure 2 As shown, it includes: site and equipment layout, background data acquisition, test piece installation and debugging, establishment of stable working conditions, automatic rotation according to angle sequence and acquisition of infrared and aerodynamic data, and data post-processing and analysis.

[0043] Specific Example 2 This specific example, based on the system in Specific Example 1, focuses on explaining its key data processing methods and test criteria.

[0044] 1. Multi-Temperature Range Data Fusion Method: Because the high-temperature portion of the nozzle test piece 3 and its exhaust plume radiates extremely strongly in the mid-wave band, exceeding the upper limit of a single linear measurement range of the thermal imager, this system employs a segmented measurement strategy. At each azimuth measurement point, the mid-wave thermal imager 7 acquires 50 frames of images in each of its four preset temperature ranges. During processing, for the same pixel, its calibrated radiance value in the four range datasets is compared. Typically, the low-temperature range will saturate for high-temperature targets (outputting the maximum value), while the high-temperature range may be insensitive to the low-temperature portion (outputting a value close to the minimum value). Through cross-comparison, the maximum value among the four values ​​is selected as the "true value" of the pixel, thereby reconstructing a complete, high dynamic range mid-wave radiance image.

[0045] 2. Criteria for the Effectiveness of Jet Stream Acquisition: To ensure that the infrared measurement includes the complete jet stream radiation, the system software sets two criteria that must be met simultaneously during acquisition for the data to be saved: (a) Geometric criterion: Based on the thermal imager's field of view and distance, calculate the axial length of the jet stream covered by the image, which must be no less than 10 times the diameter of the turbine outlet of the turbojet engine (approximately 0.15m * 10 = 1.5m in this specific example); (b) Radiation criterion: On the preprocessed image, sample along the jet stream edge contour and calculate its average radiance, which must be no less than 110% of the average radiance of the background area (far from the target). These two criteria, in terms of both physical size and signal strength, jointly ensure that the jet stream is completely captured.

[0046] 3. Background Removal and Radiation Intensity Calculation: The data processing unit employs a classic dual-measurement method to remove the background. First, before the test specimen is positioned, an infrared image of the pure background is acquired, and its integrated radiation intensity I2 is calculated. Then, an image containing the target is acquired during the experiment, and the integrated radiation intensity I1 (target + background) is calculated. The final net radiation intensity of the target is I = I1 - I2. This method effectively eliminates the influence of environmental stray radiation.

[0047] Specific Example 3 This specific example demonstrates an actual test and its results using the system described in Specific Example 1 and the method described in Specific Example 2.

[0048] The experiment was conducted at night during winter, with an atmospheric temperature of approximately 5°C. The test subject was a scaled-down binary nozzle model. During the experiment, the blower was first started at 5-70% speed, then the micro turbojet engine 2 was started, and the speed was steadily increased to 50,000 rpm. The fuel supply was adjusted to stabilize the turbine inlet temperature at around 850 K. At this time, the total inlet temperature of the nozzle model's inner tube was measured to be 846.6 K, and the total pressure was 105.7 kPa; the total inlet temperature of the outer tube was 304.8 K, and the total pressure was 108.3 kPa. After the operating conditions stabilized, the system automatically rotated the turntable in the sequence of 0°, 5°, 10°, ..., 90°, automatically completing the data acquisition of the medium-wave (4 intervals) and long-wave thermal imagers at each angle.

[0049] Time-averaging, background removal, effective area extraction, and radiation intensity integration were performed on all acquired thermal images (50 frames per angle, band, or interval). Finally, the distribution curves of the integrated radiation intensity of the nozzle model in the mid-wave (3-5μm) and long-wave (8-14μm) bands in the horizontal plane as a function of azimuth angle were obtained.

[0050] The results show that within the 0°–90° range, the integrated mid-wave radiation intensity ranges from 1.68 W / sr to 11.88 W / sr, and the integrated long-wave radiation intensity ranges from 2.34 W / sr to 16.41 W / sr. The radiation intensity generally decreases with increasing angle (from directly behind to the side). Maximum values ​​for mid-wave and long-wave radiation occur near 5° and 10°, respectively, which is attributed to the larger visible area of ​​the high-temperature wall surface at smaller angles. The decreasing trend of mid-wave radiation intensity slows down after 65°, which is attributed to the increased contribution of high-temperature gas radiation observed laterally. These data are consistent with theoretical expectations, validating the effectiveness and accuracy of the proposed testing system and method.

[0051] The system of this invention also revealed some areas for optimization during testing. For example, frost on the background baffle may increase reflection error, and the outer gas supply hose may be burned by backfire. These issues have been resolved in specific implementations by changing materials or improving operations, and can be considered as directions for further optimization, but do not affect the substantive content of this invention.

[0052] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An infrared testing system for the exhaust nozzle of a small mobile turntable engine, characterized in that, The engine (2) is set on the rotating platform of the turntable system (1). At this time, the engine (2) is used as the engine to be tested, and the turntable system (1) is used to drive the engine (2) to be tested to rotate 0 to 360° in the horizontal plane. A thermal imager, with its thermal imaging lens positioned at the exhaust nozzle outlet of the engine (2) under test, is used to detect the temperature distribution and infrared radiation distribution of the exhaust flame of the engine (2) under test. The thermal imager includes at least one medium-wave thermal imager (7) and at least one long-wave thermal imager (8) for detecting temperature distribution under different response infrared radiation wavelengths; The control system includes an industrial computer (11) and a remote control computer (12). The remote control computer (12) communicates with the rotating platform of the turntable system (1), the blower (5), the control unit ECU of the engine under test (2), the thermal imager, and the industrial control computer (11) via Ethernet or serial port. The remote control computer (12) is used to control the rotation angle of the rotating platform to drive the engine (2) under test, thereby adjusting the azimuth angle of the engine (2) under test relative to the thermal imager; at the same time, it controls the operation of the engine (2) under test and synchronously triggers the thermal imager and the industrial control computer (11) to collect data. Meanwhile, the industrial control computer (11) synchronously collects the temperature and pressure signals from the thermocouples and pressure sensors installed in the inner and outer ducts of the engine (2), and receives the digital image stream from the thermal imager. It also includes a generator (6), which is electrically connected to the thermal imager, the rotating platform, the industrial computer (11) and the remote control computer (12) to supply power to each component.

2. The infrared testing system for the exhaust nozzle of a small mobile turntable engine as described in claim 1, characterized in that, It also includes a black tarpaulin and a black background baffle. The black tarpaulin is placed on the ground between the thermal imager and the turntable base. The black background baffle is supported and shielded at the exhaust nozzle outlet of the engine (2) under test for background purification, so that the thermal imager can acquire high-fidelity images.

3. The infrared testing system for the exhaust nozzle of a small mobile turntable engine as described in claim 1, characterized in that, It also includes a nozzle (3), which is coaxially positioned behind the tail nozzle of the engine (2). At this time, the engine (2) provides a high-temperature gas source for the inner channel of the nozzle (3). The nozzle (3) is the nozzle to be tested. The turntable system (1) is used to drive the nozzle (3) to be tested to rotate 0 to 360° in the horizontal plane. The air outlet of the blower (5) is connected to the outer bypass of the nozzle (3) to be tested through the outer bypass air collection pipe (4) to provide adjustable outer bypass cooling air; The thermal imager has its thermal imaging lens set at the outlet of the nozzle (3) to be tested, and is used to detect the temperature distribution and infrared radiation distribution of the nozzle wall and the tail flame of the nozzle (3) to be tested. The remote control computer (12) is used to control the rotation angle of the nozzle (3) to be tested driven by the rotating platform, thereby adjusting the azimuth angle of the nozzle (3) relative to the thermal imager; at the same time, it controls the air supply frequency of the blower (5), that is, adjusts the cooling air flow of the outer duct of the nozzle (3) to be tested; controls the operation of the engine (2), and synchronously triggers the thermal imager and the industrial control computer (11) to collect data; at the same time, the industrial control computer (11) synchronously collects the temperature and pressure signals from the K-type thermocouples and pressure sensors installed in the inner and outer duct inlets of the nozzle (3), and receives the digital image stream from the thermal imager; It also includes a generator (6), which is electrically connected to the thermal imager, blower (5), rotating platform, industrial control computer (11) and remote control computer (12) respectively, and is used to supply power to each component.

4. The infrared testing system for the exhaust nozzle of a small mobile turntable engine as described in claim 3, characterized in that, It also includes a black tarpaulin and a black background baffle. The black tarpaulin is placed on the ground between the thermal imager and the turntable base. The black background baffle is supported and blocked at the nozzle outlet of the nozzle (3) to be tested, for background purification, so that the thermal imager can acquire high-fidelity images.

5. The infrared testing system for the exhaust nozzle of a small mobile turntable engine as described in any one of claims 1 to 4, characterized in that, The medium-wave thermal imager (7) has a response infrared radiation wavelength of 3-5 μm, and the long-wave thermal imager (8) has a response infrared radiation wavelength of 8-14 μm. Infrared thermal images are collected at a distance of 25-45 m from the tail nozzle to be measured.

6. The infrared testing system for the exhaust nozzle of a small mobile turntable engine as described in any one of claims 1 to 4, characterized in that, The turntable system (1) includes a turntable base, with casters and adjustable feet installed at the bottom of the turntable base for easy movement, leveling and locking. The industrial control computer (11) is installed inside the turntable base. The rotating platform is installed on the turntable base. The engine (2) and nozzle (3) to be tested are fixedly installed on the rotating platform by the bearing mounting bracket. The turntable base has a built-in servo motor and worm gear reducer, which are controlled and driven by a remote control computer (12). The servo motor and worm gear reducer are used to control the rotation angle, which is fed back by a high-precision encoder. The positioning accuracy is higher than 0.1°.

7. An infrared testing method implemented by the infrared testing system for the exhaust nozzle of a small mobile turntable as described in claim 1 or 2, characterized in that, Specifically, the following steps are included: Step 1: Install the engine (2) to be tested on the rotating platform of the turntable system (1), use the remote control computer (12) to control the operation of the engine (2), and lay out a black tarpaulin and a black background baffle. Step 2: Turn off the ambient light and control the rotating platform to rotate and adjust the azimuth angle between the tail nozzle of the engine (2) and the thermal imager. At the same time, under different azimuth angle conditions, use the long-wave thermal imager (8) to collect temperature distribution data and generate long-wave visualized thermal images. Use the medium-wave thermal imager (7) to repeatedly collect temperature distribution data in different temperature measurement ranges and generate multiple medium-wave visualized thermal images. Step 3: Select medium-wave and long-wave visualized thermal images containing tail jets with a visible length of not less than 10 times the engine turbine outlet diameter, and where the radiance at the edge of the medium-wave and long-wave visualized thermal images is not less than 110% of the average radiance of the background. These are considered as valid medium-wave and long-wave visualized thermal images, and the corresponding temperature distribution data are considered valid data. This yields the medium-wave and long-wave radiation intensity I of the engine (2) to be tested and the background. 1中波 and I 1长波 ; Step 4: Remove the engine to be tested (2), and repeat the process of Step 2 to collect the mid-wave and long-wave radiation intensity I of the full field of view background. 2中波 and I 2长波 ;at this time Then, the medium-wave and long-wave radiation intensity I of the engine (2) to be tested can be calculated according to the formula. 中波 and I 长波 The specific formula is as follows: I 中波 = I 1中波 - I 2中波 ; I 长波 = I 1长波 - I 2长波 。 8. The infrared testing method for the exhaust nozzle of a small mobile turntable engine as described in claim 7, characterized in that, In step one, The preset angle interval is at least 5°, and the platform is rotated step by step. For each angle, the industrial control computer (11) receives the digital image stream of the thermal imager to realize the comprehensive test of the azimuth angle, and obtain the distribution of infrared radiation characteristics with azimuth angle through the comprehensive test. Among them, infrared radiation characteristics include temperature distribution, infrared radiance, and integrated radiation intensity; Meanwhile, in step two, the maximum radiance of each image pixel is controlled by the remote control computer (12) to control the medium-wave thermal imager (7) to collect temperature distribution data in four temperature ranges: 0-40℃, 30-120℃, 110-300℃, and 280-650℃, respectively, and generate a medium-wave visualized thermal image. For each pixel of the medium-wave visualized thermal image, the maximum radiance of different temperature measurement ranges is cross-compared and selected as the true value, thereby reconstructing a complete medium-wave radiance image with a high dynamic range, so as to solve the measurement distortion problem caused by the temperature radiation at the tail nozzle of the engine (2) exceeding the linear range of a single interval.

9. An infrared testing method implemented by the infrared testing system for the exhaust nozzle of a small mobile turntable as described in claim 3 or 4, characterized in that, Specifically, the following steps are included: Step 1: Install the nozzle (3) to be tested on the rotating platform of the turntable system (1), use the remote control computer (12) to control the engine (2) to run to provide a high-temperature gas source for the inner duct of the nozzle (3) to be tested, and at the same time control the blower (5) to provide outer bypass cooling air for the outer bypass duct of the nozzle (3); at the same time, lay out black tarpaulin and black background baffle. Step 2: Turn off the ambient light and control the rotating platform to rotate and adjust the azimuth angle between the tail nozzle of the nozzle (3) and the thermal imager. At the same time, under different azimuth angle conditions, use the long-wave thermal imager (8) to collect temperature distribution data and generate long-wave visualized thermal images. Use the medium-wave thermal imager (7) to repeatedly collect temperature distribution data in different temperature measurement intervals and generate multiple medium-wave visualized thermal images. Step 3: Select medium-wave and long-wave visualized thermal images containing tail jet visible lengths no less than 10 times the engine turbine outlet diameter, and where the radiance at the edges of the medium-wave and long-wave visualized thermal images is no less than 110% of the average radiance of the background. These are considered valid medium-wave and long-wave visualized thermal images, and the corresponding temperature distribution data are considered valid data. This yields the medium-wave and long-wave radiation intensities I of the nozzle (3) to be measured and the background. 1中波 and I 1长波 ; Step 4: Remove the nozzle to be tested (3), and repeat the process of Step 2 to collect the mid-wave and long-wave radiation intensity I of the full field of view background. 2中波 and I 2长波 ;at this time Then, the mid-wave and long-wave radiation intensities I of the nozzle (3) to be tested can be calculated according to the formula. 中波 and I 长波 The specific formula is as follows: I 中波 = I 1中波 - I 2中波 ; I 长波 = I 1长波 - I 2长波 。 10. The infrared testing method for the exhaust nozzle of a small mobile turntable engine as described in claim 9, characterized in that, In step one: The preset angle interval is at least 5°, and the platform is rotated step by step. For each angle, the industrial control computer (11) receives the digital image stream of the thermal imager to realize the comprehensive test of the azimuth angle, and obtain the distribution of infrared radiation characteristics with azimuth angle through the comprehensive test. Among them, infrared radiation characteristics include temperature distribution, infrared radiance, and integrated radiation intensity; Meanwhile, in step two, the maximum radiance of each image pixel is controlled by the remote control computer (12) to control the medium-wave thermal imager (7) to collect temperature distribution data in four temperature ranges: 0-40℃, 30-120℃, 110-300℃, and 280-650℃, respectively, and generate a medium-wave visualized thermal image. For each pixel of the medium-wave visualized thermal image, the maximum radiance of different temperature measurement ranges is cross-compared and selected as the true value, thereby reconstructing a complete medium-wave radiance image with a high dynamic range, so as to solve the measurement distortion problem caused by the temperature radiation at the tail nozzle of the nozzle (3) exceeding the linear range of a single interval.

Images