scholarly journals Experimental Research on the Hydration Heat Temperature Field of Hollow Concrete Piers

2014 ◽  
Vol 8 (1) ◽  
pp. 482-487 ◽  
Author(s):  
Jun Peng ◽  
Chunping Tang ◽  
Liangliang Zhang ◽  
Ayad Thabit Saeed
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Hydration Heat ◽  
Maximum Temperature ◽  
Concrete Bridge ◽  
Central Temperature ◽  
Heat Temperature ◽  
Surface Cracking ◽  
Removal Time ◽  
Short Period

Measuring points were observed continuously to reveal the hydration heat temperature distribution of hollow concrete bridge pier. The results showed that as the thickness of the pier increased, the central temperature of the pier increased significantly due to hydration and the heat was difficult to be dissipated. The hydration temperature accounted for up to 70% of the maximum temperature rise during 20 h and reached the maximum temperature at 24 h after pouring the concrete. There was a jump value between the central temperature and surface temperature in a short period after removing the framework. The jumping was the most dangerous moment for the cracking of pier surfaces. Therefore, the formwork removal time has to be determined prudently and corresponding measures have to be conducted to reduce the possibility of pier surface cracking.

scholarly journals Two-channel time-optimal control of induction heating process with maximum temperature constraint

2020 ◽  
Vol 28 (2) ◽  
pp. 41-58
Author(s):  
Natalya A. Il`ina
Keyword(s):  
Optimal Control ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Induction Heating ◽  
Time Optimal Control ◽  
Maximum Temperature ◽  
Heating Process ◽  
Problem Of Time ◽  
Control Actions ◽  
Time Optimal

The formulation and method of solution of the problem of time-optimal control of induction heating process of an unlimited plate with two control actions on the value of internal heat sources with technological constraint in relation to a one-dimensional model of the temperature field are proposed. The problem is solved under the conditions of a given accuracy of uniform approximation of the final temperature distribution over the thickness of the plate to the required. The method of finite integral transformations is used to search for the input-output characteristics of an object with distributed parameters with two control actions. The preliminary parameterization of control actions based on analytical optimality conditions in the form of the Pontryagin maximum principle is used. At the next stage reduction is performed to the problem of semi-infinite optimization, the solution of which is found using the alternance method. The alternance properties of the final resulting temperature state at the end of the optimal process lead to a basic system of relations, which, if there is additional information about the shape of the temperature distribution curve, is reduced to a system of equations that can be solved. An example of solving the problem of time-optimal control of temperature field of an unlimited plate with two offices is carried out in two stages. At first stage the case of induction heating without maximum temperature constraints is considered, at the second stage is carried out on the basis of the results of the first stage to obtain the solution subject to the limitation on the maximum temperature of the heated billet.

Study on Electromagnetic Heating Process of Wind Power Gear: Temperature Morphology and Evolution

2020 ◽  
Vol 13 (3) ◽  
Author(s):  
Huaiyu Wen ◽  
Yi Han ◽  
Xiaobo Zhang ◽  
Feng Liu ◽  
Hongwang Zhang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Wind Turbine ◽  
Tooth Profile ◽  
Maximum Temperature ◽  
Heating Process ◽  
Central Section ◽  
Maximum Temperature Difference ◽  
Constant Change ◽  
Boltzmann Function

Abstract As a key component of wind turbine, the surface strengthening treatment of wind turbine gear is crucial to enhance its performance and service life. In the process of tooth-by-tooth induction heating, clear temperature distribution and process evolution could realize the lean control of heating effect and quality. In this article, the tooth-by-tooth heating process under the v-shaped inductor was studied to analyze the temperature field morphology and its evolution process. The results show that in the tooth profile region, the boundary morphology of the temperature field near the central section of the heating region conforms to the Boltzmann function, while the far sections conform to the normal distribution. At the end of heating, from the surface to the depth of the heating layer and from the heating center to both sides, both the maximum temperature difference and the distribution temperature are reduced. Meanwhile, the maximum temperature point near the central section is offset during the evolution of the temperature field morphology. The change of physical properties of materials and induced eddy distribution caused by involute structure and the constant change of temperature gradient are the fundamental reasons for the appearance of nonuniform temperature field and temperature excursion. The spatiotemporal variation of the hottest point was found, and the temperature morphology and evolution were revealed, which would provide a theoretical basis for adjusting the temperature distribution of tooth profile according to the requirements of different heating layers.

scholarly journals Analysis of Sunshine Temperature Field of Steel Box Girder Based on Monitoring Data

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Hailin Lu ◽  
Jing Hao ◽  
Jiwei Zhong ◽  
Yafei Wang ◽  
Hongyin Yang
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Maximum Temperature ◽  
Temperature Model ◽  
Bridge Site ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Box Girder ◽  
Steel Box Girder

In this study, based on the recorded meteorological data of the bridge site, a spatial-temporal temperature model of a 3-span steel box girder is developed through applying the thermal analysis software TAITHERM. Firstly, the rationality and dependability of the proposed spatial-temporal temperature model are adequately verified by means of implementing the comparison with the measurement data. Then the temperature distribution of the steel box girder is analyzed and discussed in detail. The analytical results show that the time of the bottom of pavement reaching the daily maximum temperature lags behind the top of pavement by 2 or 3 hours due to the thermal insulation effect of pavement, and the maximum vertical temperature gradient of the structure exceeds the existing standards. Moreover, with the help of the analytical model, a parametric study of comprehensively meteorological factors is also performed. The results of the sensitivity analysis indicate that solar radiation is the most significant factor affecting the maximum vertical temperature gradient of the steel box girder, followed by air temperature and wind speed. After that, with the representative values of the extreme meteorological parameters during 100-year return period in Wuhan City in China being considered as the thermal boundary conditions, the temperature distribution of the steel box girder is further studied for investigation purpose. The results demonstrate that the heat conduction process of the steel box girder has distinct “box-room effect,” and it is of great necessity to consider both the actual weather conditions at the bridge site and the “box-room effect” of steel box girder when calculating thermal behaviors of bridge structures. Finally, it is related that the particular method proposed in this paper possesses a satisfactory application prospect for temperature field analysis upon various types of bridges in different regions.

Study on Hydrated Heat Temperature Field of Thick Raft Concrete Foundation Using FEM Analysis

2013 ◽  
Vol 838-841 ◽  
pp. 65-68
Author(s):  
Zhen Xiao Xue ◽  
Yu Wen Ju
Keyword(s):  
Temperature Field ◽  
Temperature Rise ◽  
Fem Analysis ◽  
Maximum Temperature ◽  
Element Analysis ◽  
Solidification Temperature ◽  
Adiabatic Temperature Rise ◽  
Heat Temperature ◽  
Measurement Systems ◽  
Massive Concrete

Based on a wind turbine thick concrete raft foundation for the engineering background, through the adiabatic temperature rise test, the datum of the hydration heat of concrete are obtained; and concrete solidification temperature field numerical simulation and analysis are conducted by finite element analysis software ANSYS; by means of the temperature sensor measurement systems, the foundation concrete pouring process variation of the temperature field is obtained by real-time monitoring. Studies show that: the temperature rise inside the concrete points has the same trend, but the peak and the peak of the age are different. The maximum temperature inside the concrete is mostly shown in the initial 3-5d of concreting; temperature gradient along the thickness direction of the foundation is obvious; massive concrete is significantly affected by the outside temperature.

Numerical Simulation of Temperature Field in the Cyclone

2012 ◽  
Vol 614-615 ◽  
pp. 208-211
Author(s):  
Zhen Wei Zhang ◽  
Ying Yu ◽  
Jie Leng ◽  
Su Juan Zhang
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Turbulence Model ◽  
Temperature Difference ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Inlet Tube ◽  
Higher Temperature ◽  
Air Compression

The temperature distribution of the cyclone was analyzed in the presented work, which was imitated by using RSM turbulence model of software FLUENT. Temperature difference in different regions is less than one centigrade degree with the maximum temperature in the cone part and the minimum temperature in inlet tube and cylinder part of the cyclone, what’s more, the temperature is relatively higher near the wall. The air compression can lead the higher temperature in the lower part, so the cone part has the maximum temperature. The higher temperature near the wall is caused by the friction between the wall and flow.

Numerical Simulation of Temperature Field in the Cyclone

2012 ◽  
Vol 479-481 ◽  
pp. 462-466
Author(s):  
Ping Yang Xiao ◽  
Zhen Wei Zhang
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Turbulence Model ◽  
Temperature Difference ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Inlet Tube ◽  
Higher Temperature ◽  
Air Compression

This paper mainly focuses on the numerical simulation of temperature field in the cyclone separation. The authors took advantage of RSM turbulence model of software FLUENT to imitate the temperature field. This thesis puts forward the temperature distribution of the cyclone, and figures out that the overall temperature is 373°C. Temperature difference in different region is less than one centigrade degree with the maximum temperature in the cone part and the minimum temperature in inlet tube and cylinder part of the cyclone, what’s more, the temperature is relatively higher near the wall. The air compression can lead the higher temperature in the lower part, so the cone part has the highest temperature. The higher temperature near the wall is caused by the friction between the wall and flow.

scholarly journals Non-Uniform Temperature Field of Spatial Grid Structure under Construction Induced by Solar Radiation

2020 ◽  
Vol 10 (7) ◽  
pp. 2445
Author(s):  
Deshen Chen ◽  
Hongliang Qian ◽  
Huajie Wang ◽  
Wucheng Xu ◽  
Jingfang Li
Keyword(s):  
Numerical Simulation ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Solar Radiation ◽  
Test Data ◽  
Maximum Temperature ◽  
Uniform Temperature ◽  
Grid Structure ◽  
Spatial Grid ◽  
Under Construction

The temperature of spatial structures under construction can have a significant non-uniform distribution induced by intense solar radiation. This temperature distribution affects the component assembly and results in closure difficulties, potentially causing safety hazards. A spatial grid structure model was designed and subjected to temperature field test under sunlight to study the temperature distribution of the structure and for comparison with numerical simulation methods. The distribution characteristics and the time-varying laws were analyzed based on the test data. Then, the ray-casting algorithm was introduced to analyze the shadow influence between members, so that the temperature distribution of the model was simulated accurately, which was verified by the test data. The results show that the spatial grid structure had an obvious non-uniform temperature distribution, with a maximum temperature rise of 16 °C when compared with ambient temperature and a maximum temperature difference between members of 11 °C. The variation laws were gained both from the test and the numerical simulation. The numerical simulation method proposed herein can be used to calculate the shadow distribution and the temperature field of the structure effectively. The research methods and conclusions can provide valuable references for thermal design, monitoring, and control of spatial grid structures.

scholarly journals Study of Temperature Field Distribution in Topographic Bias Tunnel Based on Monitoring Data

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1492
Author(s):  
Tao Zhang ◽  
Lei Nie ◽  
Min Zhang ◽  
Shulin Dai ◽  
Yan Xu ◽  
...  
Keyword(s):  
Temperature Field ◽  
Heat Of Hydration ◽  
Surrounding Rock ◽  
Maximum Temperature ◽  
Rock Temperature ◽  
Topographic Bias ◽  
Short Period ◽  
Annual Minimum Temperature ◽  
Triangular Function ◽  
Secondary Lining

In recent decades, numerous tunnels have been built in the cold region of China. However, the temperature field of topographically biased tunnels in the monsoon freeze zone has not been sufficiently studied. In this study, we monitored the temperature of the surrounding rock in two topographic bias sections of the Huitougou Tunnel and analyzed the results by fitting them to the monitoring results. The results showed that the temperature of the surrounding rock on both sides after tunnel excavation varied periodically in an approximate triangular function. As the distance from the cave wall increased, the annual average temperature of the surrounding rock did not change significantly, the amplitude decreased, and the delay time increased, while the annual maximum temperature decreased, and the annual minimum temperature increased. The heat generated by blasting, the heat of hydration of the primary and secondary lining, and the decorated concrete all caused a significant increase in the temperature of the surrounding rock within 4 m for a short period of time. Both construction and topographic factors led to asymmetry in the distribution of the surrounding rock temperature in different ways. The results of this paper are intended as a reference for other studies on temperature in deviated tunnels.

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