scholarly journals NUMERICAL METHOD FOR DETERMINING TEMPERATURE FIELD OF A LINEAR OBJECT UNDER EXTERNAL THERMAL INFLUENCE

2020 ◽  
Vol 20 (3) ◽  
pp. 49-58
Author(s):  
N.M. Yaparova ◽  
◽  
T.P. Gavrilova ◽  
Keyword(s):  
Thermal State ◽  
Initial Conditions ◽  
Heat Transfer Process ◽  
Temperature Measurements ◽  
Temperature Fields ◽  
Automated Control ◽  
Use Of Data ◽  
Measurement Results ◽  
Linear Object ◽  
Thermal Influence

The use of data analysis technologies for processing the temperature measurement results is aimed at solving the problems of controlling the parameters of controlling thermal modes, monitoring the thermal state of the main industrial equipment, as well as issues of integrity and availability of data circulating in automated control systems for technological processes.The article is devoted to the problem of determining non-stationary temperature fields in-side an object from the noisy results of surface temperature measurements and the parameters of external thermal effect on its surface. Mathematically, the heat transfer process is represent-ed by a parabolic equation, includes initial conditions, as well as boundary conditions formed from temperature measurements on the object’s surface and in accordance with the character-istics of the external thermal regime.

Thermal Wake of a Single Rising Air Bubble in a Large Body of Stagnant Liquid

2007 ◽  
Author(s):  
Majid Molki ◽  
Bahman Abbasi
Keyword(s):  
High Speed ◽  
Thermal Field ◽  
Large Body ◽  
Heat Transfer Process ◽  
Computational Effort ◽  
Temperature Fields ◽  
High Speed Photography ◽  
Three Dimensional Model ◽  
Surrounding Water ◽  
Air Bubble

A computational effort was undertaken to study the thermal field behind a slowly rising solitary air bubble. Starting from rest, the bubble moves upward in water due to buoyancy force in the gravitational field and induces both internal and external motion. The bubble, being colder than the surrounding water, is heated by water. The upward motion deforms the shape of the bubble and generates a convective heat transfer process. Variation of temperature at the gas-liquid interface causes a local variation of surface tension. Although the problems of this type have been generally treated by the axisymmetric assumption, the present work employs a three-dimensional model that captures the azimuthal variation of flow parameters. High-speed photography was employed to visualize the bubble evolution from the onset until the bubble reached a certain velocity. The computations were performed using the finite-volume and Volume of Fluid (VOF) techniques. The shape and evolution of the bubble as predicted by the computations are compared with those captured on the high-speed photographs. The computations revealed details of the pressure and temperature fields inside and outside the bubble. They also indicated the thermal field in the wake region behind the bubble.

Passive Absorption/Emission Spectroscopy for Gas Temperature Measurements in Gas Turbine Engines

2011 ◽  
Author(s):  
Hejie Li ◽  
Guanghua Wang ◽  
Nirm Nirmalan ◽  
Samhita Dasgupta ◽  
Edward R. Furlong
Keyword(s):  
Gas Turbine ◽  
Emission Spectroscopy ◽  
Gas Absorption ◽  
Temperature Measurements ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Gas Temperature ◽  
Measurement Results ◽  
Passive Absorption ◽  
Hot Surface

A novel technique is developed to simultaneously measure hot surface and gas temperatures based on passive absorption/emission spectroscopy (PAS). This non-intrusive, in situ technique is the extension of multi-wavelength pyrometry to also measure gas temperature. The PAS technique uses hot surface (e.g., turbine blade) as the radiation source, and measures radiation signals at multiple wavelengths. Radiation signals at wavelengths with minimum interference from gas (mostly from water vapor and CO2) can be used to determine the hot surface temperature, while signals at wavelengths with gas absorption/emission can be used to determine the gas temperature in the line-of-sight. The detection wavelengths are optimized for accuracy and sensitivity for gas temperature measurements. Simulation results also show the effect of non-uniform gas temperature profile on measurement results. High pressure/temperature tests are conducted in single nozzle combustor rig to demonstrate sensor proof-of-concept. Preliminary engine measurement results shows the potential of this measurement technique. The PAS technique only requires one optical port, e.g., existing pyrometer or borescope port, to collect the emission signal, and thus provide practical solution for gas temperature measurement in gas turbine engines.

Investigation of Filtered Rayleigh Scattering Techniques for Rig Testing Diagnostics

2014 ◽  
Author(s):  
Jordi Estevadeordal ◽  
Dmitry Opaits ◽  
Chiranjeev Kalra
Keyword(s):  
Rayleigh Scattering ◽  
High Pressures ◽  
Imaging Techniques ◽  
Mixing Layer ◽  
Temperature Measurements ◽  
Temperature Fields ◽  
Gas Temperature ◽  
Iccd Camera ◽  
Gas Molecules ◽  
Combustion Tests

A laboratory investigation of Filtered Rayleigh Scattering (FRS) techniques for high-resolution and high-accuracy temperature measurements in rig tests with high pressures and temperatures and combustion is presented. Imaging techniques based on filtered Rayleigh scattering have the potential for two-dimensional (2D) and near wall measurement of gas velocity and temperature fields among other properties. For gas temperature measurements, laser Rayleigh scattering from gas molecules are typically captured with an ICCD camera and temperature can be inferred from the number density measured from the image intensities. The accuracy challenges associated with property spatial variations, gas composition, and pressure and temperature conditions are investigated for the rig test environments. Representative examples including mixing layer, jet and vortex flows and flame and combustion tests are presented.

scholarly journals MEASUREMENT OF THERMAL EFFICIENCY OF HEATING BOILER WITH FURNACE WALL WATERFLOW

2019 ◽  
pp. 169-176
Author(s):  
A. S. Klimov ◽  
R. T. Emelyanov ◽  
A. F. Aleksandrov ◽  
V. A. Taranov
Keyword(s):  
Thermal Efficiency ◽  
Lower Boundary ◽  
Heating Surface ◽  
Large Error ◽  
Furnace Wall ◽  
Temperature Fields ◽  
Thermal Probe ◽  
Local Coefficients ◽  
Measurement Results ◽  
Boiler Design

This article deals with the improvement of thermal efficiency of heating boilers with furnace wall waterflow. During one cycle in a PK-38 boiler the average level of the heat flow decreases by 25–30 %. The incident heat flux is measured with a thermal probe which, however, gives a large error in the measurement results. Experiments show that the error depends on the penetration of the thermal probe into the outer surface of thermal zone as well as on cavities in sealing the thermal probe, and different thermophysical properties of the latter and metal material of the heating surface. The accuracy of the measured parameters is affected by the thermal probe sealing. It is found that the distortion of temperature fields is more significant at the lower boundary of the thermal probe junction at frequently used sealing. Studies show that the waterflow leads to the restoration of local coefficients of thermal efficiency to the previous values. The obtained results can be used in boiler design and allow improving the measurement methods for thermal efficiency of heating boilers with furnace wall waterflow.

scholarly journals Thermal Conductivity of High Performance Concrete in Wide Temperature and Moisture Ranges

10.14311/174 ◽  
2001 ◽  
Vol 41 (1) ◽  
Author(s):  
J. Toman ◽  
R. Černý
Keyword(s):  
Thermal Conductivity ◽  
High Performance ◽  
Room Temperature ◽  
High Performance Concrete ◽  
Measuring Method ◽  
Point Of View ◽  
Temperature Measurements ◽  
Temperature Fields ◽  
Measured Temperature ◽  
Hot Wire

The thermal conductivity of two types of high performance concrete was measured in the temperature range from 100 °C to 800 °C and in the moisture range from dry material to saturation water content. A transient measuring method based on analysis of the measured temperature fields was chosen for the high temperature measurements, and a commercial hot wire device was employed in room temperature measurements of the effect of moisture on thermal conductivity. The measured results reveal that both temperature and moisture exhibit significant effects on the values of thermal conductivity, and these effects are quite comparable from the point of view of the magnitude of the observed variations.

Analysis of the Influence of Transient State of the Overhead Pipeline Placed in an Open-Air Space on the Accuracy of its Insulation Assessment Based on the Results of Outer Shell Thermovision Diagnostics

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Tadeusz Kruczek
Keyword(s):  
Thermal Insulation ◽  
Thermal Protection ◽  
Thermal State ◽  
Infrared Camera ◽  
Transient State ◽  
Weather Conditions ◽  
Heat Losses ◽  
Energy Accumulation ◽  
Measurement Results

Abstract The proper thermal diagnostics of pipeline insulation is an important problem. The heat losses from the pipelines depend distinctly on the quality of this insulation. Changes in weather conditions cause transient accumulation of energy in the pipeline insulation and may cause difficulties during evaluation of the quality of the pipeline thermal insulation. Generally, the goal of this investigation was to identify the scale of energy accumulation inside thermal insulation. This is important because during the calculation of heat losses from thermal pipelines on the basis of infrared camera temperature measurement results usually a steady thermal state inside the insulation is assumed. In order to determine the distributions of the temperature inside the insulation, the calculations of the temperature changes inside the pipeline insulation for real changeable meteorological conditions with the use of software ansys-fluent and others have been carried out. Both the heat transfer between the inner pipeline tube and outer pipeline shell and energy accumulation inside the pipeline elements were considered. For the pipeline insulation evaluation purpose, different coefficients for the analysis of energy accumulation scale were defined and used. The measurement results of the temperature of inner pipeline tube and outer pipeline shell gathered during the operation of the special experimental rig were used as input data for the aforementioned numerical simulations. In these calculations, they constituted the first (Dirichlet's) boundary condition. The conclusions resulting from this work are useful for specialists involved in the technical evaluation of the thermal protection features of pipelines.

Dual Wavelength Temperature Monitoring of TBC Coated Alstom 13E2 Turbine Blades

2003 ◽  
Author(s):  
R. A. Rooth ◽  
W. Hiemstra
Keyword(s):  
Temperature Measurement ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Temperature Measurements ◽  
Primary Interest ◽  
Long Wavelength ◽  
Work Related ◽  
Fiber Technology ◽  
Measurement Results ◽  
First Time

Through rapid developments in fiber technology and data acquisition technology, pyrometry has become a successful tool for the measurement of gas turbine blade temperatures. The technology enables gas turbine owners and operators to monitor the blades and to optimise the exploitation of their assets in terms of efficiency and maintenance. With the application of thermal barrier coatings on turbine blades, pyrometry faces a new challenge as these coatings are not opaque at commonly used wavelengths. The application of TBC’s to protect the metal blades allows an increase of the firing temperature, increasing the efficiency of the installation, but is potentially an additional cause of locally overheating blades in the case the coating comes off. The present paper reports on the results of experimental work related to the temperature measurement on an in service Alstom 13E2 turbine with TBC coated first stage blades. Temperature measurements have been performed with both short- and long wavelength instruments (1 μm and 10 μm). The optical characteristics of ZrO2 material at a range of temperatures have been determined. These characteristics are important in the implementation of an algorithm that calculates the metal temperature from the temperature measurement results. These metal temperatures are of primary interest, This is the first time that experimental radiation temperature measurements on an industrial turbine, using both 1 and 10 μm technology, are reported. As the measurement trace over the turbine airfoil consists of areas on the blade that are covered with TBC as well as uncovered areas, a very interesting comparison on the merits of the various systems can be presented.

Heat Transfer Process Computer Simulation and Microstructure Prediction During Crystallization of Metal Alloys

2013 ◽  
Vol 43 (1) ◽  
pp. 71-78
Author(s):  
Georgi Evt. Georgiev ◽  
Sasho Popov ◽  
Valentin Manolov ◽  
Rositsa Dimitrova ◽  
Pavel Kuzmanov
Keyword(s):  
Heat Transfer ◽  
Computer Simulation ◽  
Cast Iron ◽  
Aluminum Alloys ◽  
Transfer Process ◽  
Heat Transfer Process ◽  
Metal Alloys ◽  
Temperature Fields ◽  
Microstructure Prediction ◽  
Process Computer

Abstract Processes of crystallization during casting formation from aluminum alloys, steel and cast iron have been studied using 3-D com- puter simulation. Temperature fields of castings have been obtained and the microstructure distribution of these castings has been predicted. A comparison between numerical results and experimental measurement has been performed. It is proved, that the proposed approach is suitable for investigation and analysis of casting technologies.

Elastoplastic Wave Propagation in a Rate-Sensitive Finite Rod Having a Thermal Gradient

1970 ◽  
Vol 37 (2) ◽  
pp. 315-323 ◽  
Author(s):  
P. H. Francis
Keyword(s):  
Wave Propagation ◽  
Thermal State ◽  
Nonlinear Problems ◽  
Temperature Fields ◽  
Computational Technique ◽  
Viscoplastic Material ◽  
Strong Discontinuities ◽  
Elastoplastic Wave ◽  
Propagation Of Waves ◽  
Increasing Temperature

In this paper, the problem of one-dimensional wave propagation in a bar of a thermally sensitive viscoplastic material is considered. A constitutive equation is developed which explicitly accounts for the thermal state in both the elastic and inelastic components of the strain rate. A computational technique is proposed for solving the governing hyperbolic system of equations. This technique is a synthesis of the finite-difference method and the method of characteristics, and utilizes the most attractive features of both for solving nonlinear problems involving the propagation of strong discontinuities. Some results are shown for the propagation of waves through both decreasing and increasing temperature fields.

scholarly journals How sensitive are modeled contemporary subsea permafrost thaw and thickness of the methane clathrates stability zone in Eurasian Arctic to assumptions on Pleistocene glacial cycles?

2016 ◽  
Author(s):  
Valentina V. Malakhova ◽  
Alexey V. Eliseev
Keyword(s):  
Time Scales ◽  
Thermal State ◽  
Initial Conditions ◽  
Single Point ◽  
Ice Core ◽  
Oceanic Water ◽  
Stability Zone ◽  
Glacial Cycles ◽  
The Impact ◽  
Subsea Permafrost

Abstract. Single-point simulations with a model for thermal state of subsea sediments driven by the forcing constructed from the ice core data show that the impact of initial conditions is lost after ~ 100 kyr. The time scales of temperature propagation in sediments and respective permafrost response are ~ 10–20 kyr which is longer than the present interglacial. The timings of shelf exposure during oceanic regressions and flooding during transgressions are important for representation of sediment thermal state and hydrates stability zone (HSZ). These timings should depend on the contemporary shelf depth (SD). During glacial cycles temperature at the top of sediments is a major driver of HSZ vertical boundaries change for SD of few tens of meters, while the pressure exerted by oceanic water becomes more important for larger SD. Thus, even the existence of HSZ and its disappearance might not be easily tied to oceanic transgressions and regressions.

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