Analysis Of Temperature Field Research Articles

Finite Element Numerical Simulation and Repair Process of Laser Cladding Repair of Surface Cracks on Mechanical Parts

This study focuses on the planetary gear reducer and employs ANSYS 13.0 software to perform thermo-mechanical coupled simulations for the laser cladding repair process, aiming to address gear failure caused by cracks. The optimal theoretical repair parameters were determined based on temperature and stress field analyses, and performance testing of the cladding layer was conducted to validate the feasibility of the selected parameters. The results suggest that a laser power of 140 W and a scanning speed of 8 mm/s represent the optimal theoretical parameters for the laser cladding repair of the gear workpiece. Tensile strength tests revealed that the cladding layer’s maximum tensile strength reached 1312.80 MPa, which was 1.22 times higher than that of the substrate material. Additionally, the wear resistance tests indicated that the wear loss of the cladding layer under the optimized parameters reduced from 9.3 mg for the base material to 0.5 mg, demonstrating excellent wear resistance. Thus, the mechanical properties of the cladding layer were significantly enhanced compared to the base material under these theoretical process parameters.

Dynamics of lead selenide films modification by laser annealing

The paper considers the modification of the structure and optical properties of chalcogenide films of lead selenide (PbSe) as a result of exposure to a continuous wave (CW) laser with 405 nm wavelength. The mechanisms of oxide layer formation and the accompanying changes in the optical properties of films during laser exposure were considered. Based on the measured reflection and transmission spectra of film regions modified by laser radiation with different exposure times (1–12 s), the extinction coefficient and refractive index were calculated. The study reveals significant modifications in the films' optical constants during the early stages of laser irradiation, leading to oxidation and melting, which are further stabilized by phase transitions. Additionally, temperature field analysis showed that the film's surface temperature in the laser spot's center is strongly influenced by the time-dependent absorption capacity, especially from the 3rd second of exposure onward.

Multifunctional Thermal Imaging Complex for Medical Diagnostics

Introduction. Recent developments in the field of thermal imaging technology and the accumulated experience in instrumental analysis of thermal processes in the patient’s body indicate the prospects of developing new medical thermal imaging systems (thermal imagers).Aim. Creation of a low-budget domestic thermal imaging system for medical diagnostics with expanded functionality.Materials and methods. The distribution of temperature over the surface of the human body depends on its internal state and external environment. For each person, this distribution has its own physiological characteristics, the study and interpretation of which can be significant for diagnosing specific pathologies or assessing the general (psychophysical) state of the patient. Analysis of temperature fields on the surface of the human body makes it possible to diagnose various pathological processes manifested in the form of local temperature changes in individual areas. The proposed method for thermal diagnostics involves measuring the temperature at each point of such an area simultaneously (statically) or over a period of time (dynamically). In comparison with conventional approaches, two thermal imaging sensors are used for this purpose. These include a small-sized matrix (thus being low cost) and a point sensor. Such a combination of sensors provides for the necessary discretization of the temperature field image of sufficiently large areas of the surface of the human body, when shooting from a distance significantly reduced compared to the conventional approach.Results. A conceptual electrical circuit and a layout of a modern thermal imaging system are developed. The advantages of the proposed thermal imager over similar devices are assessed. A method for recording and analyzing temperature in a certain point and temperature fields of both separate areas and large areas on the surface of the human body is proposed and tested.Conclusion. The conducted testing of a material model of the proposed thermal imaging system using the facilities of large medical institutions in St. Petersburg showed its wide functionality along with simplicity and convenience.

Research on the Geosynthetic-Encased Gravel Pile Composite Highway Foundation in Low-Temperature Stable Permafrost Regions

In low-temperature stable permafrost regions, both active and passive cooling measures are commonly employed to ensure the long-term stability of highway structures. However, despite adopting these measures, various types of structural issues caused by permafrost degradation remain prevalent in high-grade highways. This indicates that in addition to preventing permafrost melting, structural reinforcement of the foundation is still necessary. Based on the analysis of the long-term foundation temperature field and settlement using the finite element method, which was validated through an indoor top-down freeze–thaw cycle test, this paper explores, for the first time, the feasibility of applying geosynthetic-encased gravel pile composite highway foundations—previously commonly used for permafrost destruction—in low-temperature stable permafrost areas where permafrost protection is the primary principle. By analyzing the long-term temperature field, settlement behavior, and pile–soil stress ratios of permafrost foundations influenced by both the highway structure and composite foundation, it was found that when the pile diameter is 0.5 m, pile spacing is 2 m, and pile length is 11 m, the mean monthly ground temperature of the permafrost foundation will not be significantly affected. Therefore, the properly designed geosynthetic-encased gravel pile composite highway foundation can be adopted in low-temperature stable permafrost regions where permafrost protection, rather than destruction, is required.

Optimization of Hemolytic Performance for Blood Pump Based on Temperature Field Analysis and Three Control Strategies

Optimization of Hemolytic Performance for Blood Pump Based on Temperature Field Analysis and Three Control Strategies

Analysis of transient temperature field of five-phase induction motor with composite winding under different operating conditions

Temperature rise of the multiphase motor is closely related to its operating condition and winding connection mode. When the motor is in overload and fault-tolerant operation, the unbalanced winding current may lead to the local overheating of the winding, which threatens the safe operation of the motor. In order to reveal the heating state in the five-phase induction motor with compound winding under different operating conditions, a new star-pentagon compound winding was constructed based on the conventional single-winding structure, and the electromagnetic loss of the studied motor with compound winding was calculated under different operating conditions by the field-circuit coupling method. On this basis, the three-dimensional fluid-thermal coupling model of the motor was established to calculate the transient temperature rise of the motor under normal working conditions and typical fault conditions of the winding. The temperature rise of the new five-phase induction motor with compound winding under different working conditions were determined, and the influence of operating conditions on the thermal performance of the motor were also obtained. The research results lay a theoretical foundation for the optimal design of multiphase motors and for further fault-tolerant control.

Temperature field analysis and compensation improvement of load cell

During the operation of load cell, heat is generated by the strain gauge and the electronics on the PCB board, which leads to temperature gradients within the sensor itself. These temperature gradients are unstable at different ambient temperatures. Compensation inaccuracies can also occur when compensating for sensor measurements at different temperatures This paper proposes a method to change the position of temperature compensation resistors to address errors caused by the temperature field effect of the strain gauge sensor itself. Without affecting the sensor’s strain measurement, the correctness of the proposed method is demonstrated through steady-state thermal simulation results in ANSYS and experimental results, effectively addressing errors caused by unstable temperature gradients during the operation of strain gauge sensors.

Profile design of grinding wheel and temperature field analysis of internal gear with parabola curve configuration

Profile design of grinding wheel and temperature field analysis of internal gear with parabola curve configuration

Research on Regulation Method of Variable-Air-Volume Air Conditioning System with “Personal Space”

In large public facilities, such as airport terminals or open-plan office spaces, the HVAC system typically consumes substantial amounts of energy. However, individuals often gather at specific areas while other zones are occupied by transient or occasional users. To minimize operational energy usage, this paper aims to reduce thermal comfort demands in non-targeted areas. This paper introduces a method for regulating the thermal environment around occupants exclusively in the variable-air-volume (VAV) air conditioning running mode. The investigation utilizes Airpak modeling and experimental verification techniques. Additionally, an analysis of temperature field and velocity field distributions within the room under the “personal space” operation mode is presented. The results suggest that adjusting the numbers of air vents, openings, airflow velocities, and air supply orientations can establish a comfortable thermal environment for inhabitants and reduce the overall ADPI value. The combined air supply mode leads to a 16.7% reduction in power usage compared to traditional full-space operation.

Experimental investigation on in-situ laser-assisted machining of single crystal silicon based on response surface methodology

Abstract In this paper, Response Surface Methodology (RSM) was utilized as a robust and convenient predictive tool to establish the correlation between process parameters in in situ laser-assisted machining and the surface roughness of single-crystal silicon. An optimized design of the diamond tool, a novel temperature field analysis method, and Response Surface Methodology (RSM) were utilized. The contribution rate of each process parameter on surface roughness was laser power > rotation speed > cutting depth > feed rate. The optimal process parameter combination is: rotation speed as 1001 r min−1, feed rate as 4.9 μm/r, cutting depth as 7.55 μm, and laser power as 28.81 W. Experimental validation of these optimal parameters compared surface roughness values obtained experimentally with those predicted. The surface roughness model showed a maximum relative error of 5.2%, with an average error of 4.8% across three experimental sets. These errors are within acceptable limits, indicating an alignment between predicted and experimental results.

Simulation and clinical validation of the breast temperature field based on a multi-point heat source model

To investigate the relationship between cell metabolism heat production and breast diseases, and to differentiate the benign and malignant nature of breast tumors based on this foundation, this study established a refined three-dimensional model of the breast suitable for analyzing the temperature field of the breast, based on the anatomical structure and physiological characteristics of the breast, using the Pennes bio-heat transfer equation. Compared to traditional breast models, this model closely approximates the physiological structure of the breast, thereby enabling a more accurate simulation of the temperature distribution within the breast for both normal and embedded tumors. This study obtains the heat production of the corresponding position of the lesion area in patients with breast tumors through the multi-point heat source model. The heat production is embedded in the breast model containing the tumor. Then, the temperature field analysis is conducted on the normal breast model and the breast model with malignant and benign tumors. Finally, the obtained temperature values are compared. The analysis reveals that the temperature values in the malignant tumor regions are higher than those in the benign tumor regions. Furthermore, based on the distribution of temperature fields, tumor sizes are estimated and compared with those observed in ultrasound images, demonstrating a close correspondence between the results. Therefore, this paper provides an essential novel analytical approach for distinguishing between benign and malignant breast cancer.

Multi-Fidelity Modelling of the Effect of Combustor Traverse on High-Pressure Turbine Temperatures

As turbine entry temperatures of modern jet engines continue to increase, additional thermal stresses are introduced onto the high-pressure turbine rotors, which are already burdened by substantial levels of centrifugal and gas loads. Usually, for modern turbofan engines, the temperature distribution upstream of the high-pressure stator is characterized by a series of high-temperature regions, determined by the circumferential arrangement of the combustor burners. The position of these high-temperature regions, both radially and circumferentially in relation to the high-pressure stator arrangement, can have a strong impact on their subsequent migration through the high-pressure stage. Therefore, for a given amount of thermal power entering the turbine, a significant reduction in maximum rotor temperatures can be achieved by adjusting the inlet temperature distribution. This paper is aimed at mitigating the maximum surface temperatures on a high-pressure turbine rotor from a modern commercial turbofan engine by conducting a parametric analysis and optimization of the inlet temperature field. The parameters considered for this study are the circumferential position of the high-temperature spots, and the overall bias of the temperature distribution in the radial direction. High-fidelity unsteady (phase-lag) and conjugate heat transfer simulations are performed to evaluate the effects of inlet clocking and radial bias on rotor metal temperatures. The optimized inlet distribution achieved a 100 K reduction in peak high-pressure rotor temperatures and 7.5% lower peak temperatures on the high-pressure stator vanes. Furthermore, the optimized temperature distribution is also characterized by a significantly more uniform heat load allocation on the stator vanes, when compared to the baseline one.

Symmetrical Martensite Distribution in Wire Using Cryogenic Cooling

This article presents the results of research on a new combined process involving multi-cycle wire-drawing and subsequent cryogenic cooling after each deformation stage. For theoretical research, modeling in the Deform software was performed. The analysis of temperature fields and the martensitic component in all models showed that for both considered thicknesses, the most effective option is a low deformation velocity and the conduct of a process without heating. The least effective option is to use an increased thickness of the workpiece at an increased deformation velocity and the conduct of a process without of heating to ambient temperature, which acts as a local cooling of the axial zone of the workpiece with an increase in the workpiece thickness. An analysis of laboratory studies on this combined process revealed that in the absence of intermediate heating of a wire between deformation cycles, 100% martensite is formed in the structure. However, if intermediate heating to 20 °C between deformation cycles is carried out, a gradient distribution of martensite can be obtained. And, since the wire has a circular cross-section, in all cases, martensite is distributed symmetrically about the center of the workpiece.

Effect of temperature on braking performance of the comb-type disc magnetorheological brake

To investigate the effect of internal temperature variation of the comb-type disc magnetorheological brake on braking performance, firstly we simulate the temperature field analysis of magnetorheological brake by using the finite element method, and verify the reasonableness of the simulation using experiments. Secondly, the temperature variation of comb magnetorheological brakes during intermittent 5 min braking and continuous braking and the effect of temperature on the braking torque were investigated experimentally. The experimental results show that as the number of braking increases, the maximum temperature inside the brake increases until saturation, while the braking torque decreases. This research helps to enhance the realization of braking stability over the effective operating temperature range.

Temperature field analysis in tunnel construction ventilation with emphasis on duct leakage and thermal conductivity

Mechanical ventilation is the primary measure for cooling during construction of high geo-temperature tunnel. Based on heat transfer theory and characteristics of press-in ventilation, a comprehensive calculation model considering the influence of construction process is proposed, and the reliability of the model is verified by on-site test. The effects of duct leakage rate and thermal conductivity of different excavation length on temperature field distribution during construction ventilation were analyzed based on the prediction model. The following conclusions are drawn: As the excavation length increases, the duct outlet temperature first increases and then decreases. The duct outlet temperature is mainly affected by geo-temperature and boundary control temperature of working face, the air leakage rate and excavation length are not the main factors. The highest temperature in the duct is about 40 °C. The distance between the position of highest temperature and working face increases with the increase of excavation length and decreases with the increase of air leakage rate. With the increase of excavation length, the impact of thermal conductivity on outlet temperature of duct is first enhanced and then stabilized under the same excavation length. The heat-insulated duct can effectively reduce the outlet air temperature and prolong the service life of the duct, while minimizing the air leakage of the duct.

Temperature Extreme Value Evaluation of Composite Beams Based on Copula Functions

The solar temperature field of steel-concrete composite girder bridges has a significant impact on structural stress. To evaluate the distribution of solar temperatures, this paper conducted analyses of the solar temperature field of the Xuefeng Lake Bridge through on-site measurements and numerical simulations. The study investigated the temperature field characteristics of the composite girders according to the temperature data. Based on the numerical simulation results, a finite element computational model for the vertical temperature gradient of the steel-concrete composite girder bridge was established, and the maximum gradient temperature values of the composite girders were calculated by using the 24-year historical data from 2000 to 2023. The extreme value parameters related to the GEV distribution model were determined. Taking into account the correlation between the annual maximum environmental temperature and wind speed, a joint distribution model was established using Copula functions. The results indicate that the average error of the numerical model is within 5%. The wind-temperature joint distribution model, considering the effects of wind speed, tends to provide more conservative results. The calculated extreme values of temperature gradient load show an expanding trend, with the exceedance probabilities for recurrence periods of 100 years, 50 years, 20 years, 10 years, and 5 years being 0.64%, 1.34%, 2.29%, 3.51%, and 7.32%, respectively.

Improvement of normalized prediction model of soil thermal conductivity

Soil thermal conductivity (k) is an important parameter for geotechnical engineering temperature field analysis and energy pile design. It is affected by various factors such as degree of saturation, dry density, and mineral composition. Due to the nonlinear correlation between k and these influencing factors, accurate prediction of k is of great significance to guide practical engineering. In this paper 337 soil thermal conductivity data were collected and the intrinsic correlations between k and the influencing factors were systematically analyzed. Based on the Johansen model, a new predictive model was developed by the multivariate probability distribution (MPD) method. The proposed model was also verified by making a comparative analysis with the empirical ones. The results show that the Johansen model has a superior performance in predicting k after the improvement of MPD analysis, in which the correlation coefficient R2 increases from 0.641 to 0.961. The prediction accuracy of the improved model is significantly better than the traditional empirical relationship models. It is recommended to use the Ke - {n, γd, Sr, Cq, Cc, Csi, Csa} model to predict the k when the soil parameters are clear.

Comparative Study of Simulation of Temperature Rise in Ring Main Unit.

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact internal structure and high current load, heat dissipation issues are particularly prominent. To address this problem, this study innovatively proposes a simplified RMU model, employing finite element simulation methods to accurately solve for the ohmic losses of conductors under actual operating conditions and obtain ohmic loss data for various components. This is the first in-depth investigation of the RMU's temperature rise problem using such a comprehensive approach. Subsequently, the temperature field was solved using two different temperature field analysis modules, with a detailed comparison and analysis of the simulation results to identify similarities, differences, and trends in temperature distribution. The results indicate that the temperature field solution model, which considers convective heat transfer, is more accurate and aligns with actual operating conditions. This research provides an innovative approach and practical solutions for the design and optimization of RMUs. Future research can further explore multiphysics coupling analysis methods to address structural design and mandatory validation issues for high and ultra-high voltage RMUs and other electrical equipment, thereby providing important insights for engineering design.

Research on temperature distribution in container ship with Type-B LNG fuel tank based on CFD and analytical method

The liquefied natural gas (LNG) fuel tank in a large container ship is loaded with liquid LNG at an ultra-low temperature (-163°C), there is a significant temperature difference in the cargo hold area where the entire fuel tank is located, which will have an important impact on the steel grade design and structural safety of the cargo tank in container ship. This paper develops two heat transfer models using Computational Fluid Dynamics method (CFD method) and an analytical method to analyze the temperature distribution in a large container ship equipped with Type-B LNG fuel tank. These models incorporate the arrangement and heat transfer characteristics of LNG fuel tanks. The temperature field analysis is conducted under typical the environmental conditions specified in the Code for the Construction and Equipment of Ships Transporting Liquefied Gas in Bulk (IGC Code) and the United States Coast Guard Code (USCG Code), based on the CFD method and the analytical method, and the results of temperature field distribution are compared. Additionally, a parametric analysis of the hull temperature field is further carried out, the results show that the thermal conductivity of the insulation layer in LNG storage tanks and the types of the loaded liquid cargo have a limited impact on the final temperature field distribution in hull structure. However, the selection of steel grade in the local structure of the cargo hold, especially in the inner hull part, may lead to significant changes.

Temperature field analysis and prediction of winter construction warm shed method based on hot air heating

The warm shed method is commonly employed in concrete construction during winter as an effective technique. This study aims to investigate the impact of different sizes and heating methods on the temperature inside the shed and the concrete through scale model testing. The hot air heating method is simulated using finite element software, and a prediction model is developed. The findings reveal an inverse relationship between the size of the warm shed and its heat preservation effect. When utilizing hot air, both the maximum temperature inside the warm shed and at the center of the concrete increase by 15.5 °C and 25.2 °C respectively compared to when employing a point heat source, resulting in earlier stabilization times of 390 min and 1000 min respectively, as well as a more uniform temperature distribution across all parts. Based on finite element simulation results, an optimal wind speed μ is proposed along with a corresponding prediction model.