In power engineering, analysis of the thermal behavior of steam turbine and development of control strategies depend on online evaluations of the temperature fields of in-service components. Due to ...the complexity of structure and the variability of operating conditions, an online reconstruction technique fused with proper orthogonal decomposition (POD) and sparse sensor data is described herein to monitor the three-dimensional (3D) transient temperature fields of a steam turbine casing. The POD-based reduced order approach was driven by the high-fidelity data of the steam turbine under several start-up conditions, and the POD was used to extract a reduced set of vectors in the orthogonal basis to capture the spatial distribution modes of 3D temperature field. As a result, the temperature fields of steam turbine casing can be reconstructed using the reduced set of vectors in the orthogonal POD basis and the corresponding coefficients, and then it is feasible to online monitor the global temperature distribution by minimizing deviations between the predicted and measured temperatures. The feasibility and accuracy of the reconstruction approach were demonstrated using two numerical examples in comparison with high fidelity data. Finally, real sensor-measured sequential temperatures were used to dynamically determine the real temperature field of the casing. Notably, the reconstructed temperatures were highly consistent with the sensor-measured temperatures, and the time delay of almost every reconstruction process was less than 0.02 s. This proposed reconstruction approach can provide reliable online monitoring for the transient temperature fields of a 3D complex component based on sparse sensors, and it will provide effective support for the design, operation and maintenance.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The ventilated disc brake of vehicles was selected as the objective of this study, which was built on 3D modeling technology. Through establishing thermo-structural coupling model, this study ...analyzed the transient temperature field of automobile brake under the condition of hard braking. Meanwhile, the test of hard braking was carried out on professional platform of vehicle test bench in this paper, and temperature curves of brake disc in radial and circumferential directions were obtained. By comparison, the experimental values and simulation values were basically equal. The rationality of the selected finite element analysis (FEA) was attributed, which provided a better theoretical basis for further experimental analysis.
•Study on temperature field of brake disc under the condition of hard braking by transient thermal-structural direction coupling method.•The experimental was carried out on professional platform of vehicle test bench under the condition of hard braking.•By comparing, the fitting degree of the experimental results and the simulation values is further linearized.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Laser protection for optical components, particularly those in high-power laser systems, has been a major concern. La1-xSrxTiO3+δ with its good optical and thermal properties can be potentially ...applied as a high-temperature optical protective coating or high-reflectivity material for optical components. However, the high-power laser ablation behavior of plasma-sprayed La1-xSrxTiO3+δ (x = 0.1) coatings has rarely been investigated. Thus, in this study, laser irradiation experiments were performed to study the effect of high-intensity continuous laser on the ablation behavior of the La1-xSrxTiO3+δ coating. The results show that the La1-xSrxTiO3+δ coating undergoes three ablation stages during laser irradiation: coating oxidation, formation and growth of new structures (columnar and dendritic crystals), and mechanical failure. A finite-element simulation was also conducted to explore the mechanism of the ablation damage to the La1-xSrxTiO3+δ coating and provided a good understanding of the ablation behavior. The apparent ablation characteristics are attributed to the different temperature gradients determined by the reflectivity and thermal diffusivity of the La1-xSrxTiO3+δ coating material, which are critical factors for improving the antilaser ablation property. Now, the stainless steel substrate deposited by it can effectively work as a protective shield layer against ablation by laser irradiation.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
In this paper, the transient temperature field and thermal stress of the slagging-off robot arm were analyzed by finite element method, the temperature distribution and change of the robot arm in one ...working cycle were determined, and the thermal stress and thermal deformation of the slag-scraping plate after the skimming was completed were solved. The results show that the temperature of the equipment in the slagging-off process can reach 206 °C, and the heat can be transferred to the position of 200mm, which will not affect the key parts in the manipulator. Due to the direct contact with molten iron, the heat stress and deformation of the slag-scraping plate are large, which may result in the high melt loss rate of the slag-scraping plate.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Objective In order to predict the development of the frozen wall before the frozen method construction and validate the rationality of the design, providing a scientific guidance for engineering ...construction, it is necessary to study the temperature field development law of frozen method construction for Shanghai Metro link passages in soft soil stratum, and propose evaluation and economic indicators. Method Taking an interval of Shanghai Rail Transit Line 15 as engineering background, the frozen wall thickness, soil temperature, brine temperature, and freezing process are analyzed. A three-dimensional numerical model of the entire stratum is established using ABAQUS finite element software to predict the development characteristics of the frozen temperature field and verify it with field-measured temperature data. Result & Conclusion The average development speed of the clay layer frozen curtain is 54.535 mm/day, while the average development speed of the silty clay layer frozen curtain is 52.450 mm/da
Accurate short-term prediction of transient temperature field (TTF) variation is crucial for the effective thermal management and safe operation of permanent magnet synchronous machine (PMSM) in ...electric drive gearbox. In this work, a novel short-term prediction method of TTF is introduced, which unifies both, thermal network topology (TNT) graph construction, and modified relational graph convolutional thermal neural network (RGCN) with supervised machine learning. First, the thermal network model of PMSM with composite cooling type is established based on lumped parameter thermal network (LPTN). Furthermore, the thermal network model is simplified as <inline-formula><tex-math notation="LaTeX">n</tex-math></inline-formula>-node TNT through loss analysis. Second, ordinary least square (OLS) is used to estimate the main components' temperatures. Considering the TNT, and integrating modified RGCN, the TTF variation prediction model of the spatial-temporal relational graph convolutional thermal neural network based on OLS (OLS-RGCN) is constructed. Finally, the accuracy of OLS-RGCN is verified by using a water-cooled PMSM dataset and a self-measured oil-cooled PMSM dataset. Experimental results show that OLS-RGCN exhibits better comprehensive prediction performance compared with the other two methods during the two datasets. Meanwhile, the global temperature errors are controlled within 5.88 <inline-formula><tex-math notation="LaTeX">^\circ \rm {C}</tex-math></inline-formula> and 2.6<inline-formula><tex-math notation="LaTeX">\,^\circ \rm {C}</tex-math></inline-formula>, respectively, when prediction time is 10 s, indicating the successful applicability of OLS-RGCN for different PMSM.
The unpredictable power fluctuation due to severe heating has been demonstrated to be a critical bottleneck technique restricting the application of magnetorheological (MR) clutches in vehicle ...industry. The aim of this study is to introduce a low-cost transient simulation approach for evaluating the heat build-up and dissipation of a liquid-cooled MR vehicle clutch. This paper firstly performs a detailed description of the developed MR clutch in terms of operation principle, material selection and configuration. Subsequently, transient temperature simulations are carried out under various conditions to reveal the distribution, variation and impact factors of the transient temperature field. Following these, an experimental setup is established for heating tests of the clutch prototype. Experimental results concerning the temperature variation of magnetorheological fluids and the maximum allowable transient slip power of the clutch prototype are presented, which in return verify the correctness and feasibility of the simulation.
