Abstract:From the perspective of performance and reliability testing, this paper analyzes the testing requirements for the engine?level test of gas turbine engine, and identifies the key parameters, including thrust, power, speed, flow rate, temperature, pressure, and vibration. The principles, applications, and development trends of the relevant testing techniques for each parameter are introduced. For thrust and power measurement, the structure of thrust measurement bench and power measurement system, along with their calibration methods, are described. In terms of rotational speed measurement, typical speed measurement systems and strategies for dealing with signal distortion are presented. Regarding flow rate measurement, velocity, differential pressure, and mass flow meters used for fuel flow measurement, as well as the structure and measurement point arrangement of the intake air flow measurement section are discussed. For temperature measurement, gas temperature measurement and wall temperature testing methods encompassing resistance temperature detectors, thermocouples, temperature?indicating paint, fluorescent temperature measurement, and radiation temperature measurement techniques are introduced. In pressure measurement, the pressure testing system is described, and the challenges and solutions for dynamic pressure testing in high?temperature environments are analyzed. In vibration measurement, the engine?level vibration testing system and the issues related to vibration measurement point arrangement are discussed. The testing techniques for the key parameters of gas turbine engine are expected to evolve towards higher accuracy, higher frequency response, and higher temperature tolerance. Meanwhile, the engine?level testing systems will tend towards intelligence and integration.

Abstract:Compared with the traditional temperature measurement technology, radiation thermometry technology offers the advantages of non?contact measurement, fast response and excellent high?temperature adaptability. It enables real?time measurement of the surface temperature distribution of key components such as turbine rotor blades. It introduces the basic principles, technical characteristics and application scope of various radiation temperature measurement methods including brightness thermometry, colorimetric thermometry, charge?coupled device (CCD) thermometry, and multi?wavelength radiation thermometry. The application and development status of radiation thermometry technology in turbine blade temperature measurement are described, and the future development direction of this technology is discussed. It is pointed out that the accuracy and reliability of radiation thermometry technology can be further improved by optimizing the design of optical probe, using more advanced algorithms, and applying new type of high?temperature?resistant materials; and that the radiation thermometry technology can be combined with thermocouple thermometry technology to build a more precise and stable turbine blade temperature monitoring system.

Abstract:Blade vibration parameters are crucial for influencing the operational efficiency and safety of major rotating equipment such as aero?engines and gas turbines. The blade vibration measurement method based on blade tip timing has become a standard technology for monitoring the health status of rotating blades. This article introduces the principle of blade tip timing measurement, describes the typical structure of the system and common measurement processes, and summarizes four key technologies of blade tip timing measurement, including high?precision extraction of blade arrival time, high signal?to?noise ratio blade vibration displacement measurement, extremely under?sampled blade vibration parameter identification, and blade fault diagnosis based on small?sample tip timing signals. It analyzes in detail the significant progress made in blade tip timing measurement methods in terms of blade tip timing sensing technology, vibration parameter identification technology, and blade fault diagnosis technology. It proposes the development trend and prospects of blade tip timing technology, and summarizes the future key research directions in the field of non?contact blade vibration measurement from four aspects: sensing signal multiplexing, uncertainty analysis and calibration, on?board application of systems, digital twin and intelligent operation and maintenance. It is expected to provide important references for the scientific development and engineering application of blade tip timing measurement technology.

Abstract:The article reviews the key parameter testing technologies for air?breathing pulse detonation engines under unsteady combustion conditions. It elaborates on the methods for measuring detonation wave pressure and gas velocity, explores the research status of piezoelectric and piezoresistive sensors as well as optical technologies, and analyzes the challenges faced by these technologies in high?temperature and high?frequency environments. The current state of the research on the measurement of pressure ratio and combustion efficiency is analyzed, and high?precision measurement schemes based on the mass?weighted average method and optical technologies are discussed. Dynamic testing methods for turbine speed and efficiency are introduced, the reasons for turbine efficiency decline under unsteady conditions are analyzed, and the design optimization suggestions are proposed. The latest advancements in thrust measurement technologies are summarized, and the high?precision thrust measurement methods based on dynamic system parameter identification and deconvolution techniques are elaborated. Finally, the future development directions of unsteady parameter testing technologies for pulse detonation boosted engines are envisioned, including improving the anti?interference capability of sensors and optical devices, optimizing combustion chamber design, developing dynamic testing systems with higher temporal and spatial resolution, and researching more intelligent multi?parameter integrated measurement systems. These efforts aim to further enhance the accuracy and reliability of unsteady parameter testing technologies for pulse detonation boosted engines and promote their engineering applications.

Abstract:A thin film strain gauge fabrication method was proposed based on high?temperature inorganic glue flattening treatment, magnetron sputtering technology and atomic layer deposition (ALD), aiming at solving the problem of high?temperature strain measurement on the surface of C / SiC composite materials. The surface of the C / SiC composite material was flattened by brushing inorganic glue, and then a thin film strain gauge consisting of a Pt sensitive layer and a composite insulating layer was prepared using magnetron sputtering and atomic layer deposition technology. Specifically, the Pt sensing layer was prepared by direct current (DC) sputtering through complex surface patterning technology with a hard?mask, achieving a resistance of 75 Ω and a thickness of 450 nm. For the insulating layers, three types of composite insulating layers (YSZ / Al?O?, Al?O??YSZ / Al?O?, and HfO??YSZ / Al?O? composite layers with a thickness of 1.2 μm) were prepared via DC sputtering and atomic layer deposition. A comparative study was emphatically conducted to evaluate the high?temperature insulation performance of the three insulating layers. The results indicated that the HfO??YSZ / Al?O? composite insulating layer exhibited the best performance, with an insulation resistance of 32.94 kΩ at 950 ℃ after multiple thermal cycles. Strain testing under a temperature range from room temperature to 600 °C revealed that the Pt strain gauge fabricated based on HfO??YSZ / Al?O? composite insulation layer achieved a maximum gauge factor (GF) of 2.93. The minimum and maximum measurement errors were 0.01% (600 °C, 133.2 με) and 6.49% (200 °C, 133.2 με), respectively. The strain gauge exhibited superior high temperature stability and strain response. The research results provide a new technical solution for high?temperature strain measurement on the surface of C / SiC composite materials, which possessed positive significance for promoting the development of high?precision strain measurement technology for thermal structural components of hypersonic vehicles.

Abstract:Due to the strong background radiation inside the aero engine, there is a large deviation between the temperature value obtained by measuring the surface of the turbine blade using the conventional radiation temperature measurement system and the actual temperature value. To address this issue, a new generation of turbine blade surface temperature measurement system was developed based on the principle of multispectral temperature measurement. The system uses movable mirror probes and fixed mirror probes to achieve high?reliability scanning, realizes efficient signal acquisition and precise control of equipment through high?speed multi?channel synchronous signal acquisition and control system, and realizes online measurement and reconstruction of three?dimensional temperature field on the blade surface by using multispectral temperature measurement modeling in complex thermal environment, multi?view three?dimensional temperature field reconstruction and other technologies. The performance indexes of the multispectral turbine blade surface temperature field measurement system were tested by using a blackbody radiation source and a dynamic calibration device, and the results showed that the system could achieve real?time online measurement of the surface temperature of turbine blades at 550 ~ 1 500 ℃, and the maximum allowable error did not exceed ± 7.5 ℃, which met the temperature measurement requirements of turbine blades. The research results provide strong support for promoting the development of thermal parameter testing technology for aeroengine turbine blades in high?temperature and complex environments.

Abstract:In order to solve the problem of low recognition accuracy of aero?engine lockwire caused by factors of the complex background, uneven illumination and small percentage of the target region, this paper proposes an improved mask region?based convolutional neural network (Mask R?CNN) model for lockwire instance segmentation. Firstly, the gamma corrections of R, G and B channels with different degrees were carried out to transform the lockwire image into pseudo?color image and enhance the contrast. Then, the dynamic snake?shaped convolution was incorporated into Resnet, the backbone network of Mask R?CNN, to make the network to adaptively focus on the slender and curved local structure during feature extraction. Then, based on the geometric features of the fuse's slender curve, dynamic snake convolution was integrated into the backbone network Resnet of Mask R?CNN, allowing the network to adaptively focus on the local structure of the slender curve during feature extraction. Finally, the CBAM attention mechanism was introduced in the feature fusion phase to retain the shallow features of small target, so as to improve the perception ability of the network on small target. The experimental results showed that the A_AP50 of the improved module mask reached 82.54%, which was improved by 5.83% compared to basic mode. This study provides strong support for digital and intelligent detection of aero?engine lockwire.

Abstract:When using pressure pipeline for measuring high?temperature pulsating pressure in aircraft engines, high?temperature condensed water may cause a state of "gas mixed with liquid" in the pressure pipeline, and using traditional dynamic models of gas medium pressure pipeline for analysis may result in significant errors. In response to this issue, a transfer function of the pressure pipeline under the condition of "gas mixed with liquid" was established based on a compressible fluid pressure pipeline system model. Pressure pipelines of the same length but different inner diameters were selected, and experimental research was conducted under different gas?liquid mixing states by adjusting pressure and gas?liquid ratio. The relationship between the dynamic characteristics of the pressure pipeline and gas?liquid ratio was obtained, and the differentiated features of the dynamic characteristics of the pressure pipeline after gas?liquid mixing under different pipe diameters were obtained. This lays the foundation for the subsequent research on the dynamic characteristics of the pressure pipeline under other complex medium conditions, and provides technical reference for improving the accuracy of dynamic pressure testing of aviation engines.

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