Practical applications of temperature distribution sensing by Raman backscattering in optical fibers

1993 ◽  
Author(s):  
Ryozo R. Yamauchi ◽  
Alan T. Shiota
Keyword(s):  
Temperature Distribution ◽  
Optical Fibers ◽  
Practical Applications

Heat transfer from a rotating disk

1956 ◽  
Vol 236 (1206) ◽  
pp. 343-351 ◽  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Laminar Flow ◽  
Turbulent Flow ◽  
Outer Part ◽  
Rotating Disk ◽  
Friction Torque ◽  
Practical Applications ◽  
A Value ◽  
Flow Heat

The flow due to a disk rotating in its own plane has been investigated theoretically by von Kármán, Goldstein, and others, but little has been published on the heat transfer. For laminar conditions theoretical solutions have been given by Millsaps & Pohlhausen and by Wagner, but for conditions when the flow is turbulent over the outer part of the disk there is no previous information. The present paper describes an experimental investigation of the heat transfer for a range of conditions from entirely laminar flow to conditions when the outer 80% of the disk area is under turbulence. For laminar flow the heat transfer agrees with Wagner’s results, but Millsap’s theory is found to give too low values and an explanation is given. For the turbulent case, which occurs in most practical applications, values are given for the heat transfer which is found to approach the expression N = 0∙015 R 0∙8 for all-turbulent flow. An attempt is made to deduce the turbulent flow heat transfer theoretically by assuming a 1/7 power law of temperature distribution, but this gives too low a value. Some measurements of the velocity and temperature profiles both for laminar and for turbulent conditions are given. For laminar flow these show fair agreement with the theoretical values. For turbulent flow the temperature ratios are higher than those of velocity, which explains the low heat transfer values calculated assuming a 1/7 power temperature distribution. The relation between heat transfer and friction torque is also discussed.

scholarly journals A New Algorithm for Reconstructing Two-Dimensional Temperature Distribution by Ultrasonic Thermometry

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Xuehua Shen ◽  
Qingyu Xiong ◽  
Weiren Shi ◽  
Shan Liang ◽  
Xin Shi ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Ultrasound Velocity ◽  
Least Square Method ◽  
Reconstruction Algorithm ◽  
Industrial Applications ◽  
Least Square ◽  
Distribution Models ◽  
Practical Applications ◽  
Reconstruction Performance ◽  
Reconstructed Temperature

Temperature, especially temperature distribution, is one of the most fundamental and vital parameters for theoretical study and control of various industrial applications. In this paper, ultrasonic thermometry to reconstruct temperature distribution is investigated, referring to the dependence of ultrasound velocity on temperature. In practical applications of this ultrasonic technique, reconstruction algorithm based on least square method is commonly used. However, it has a limitation that the amount of divided blocks of measure area cannot exceed the amount of effective travel paths, which eventually leads to its inability to offer sufficient temperature information. To make up for this defect, an improved reconstruction algorithm based on least square method and multiquadric interpolation is presented. And then, its reconstruction performance is validated via numerical studies using four temperature distribution models with different complexity and is compared with that of algorithm based on least square method. Comparison and analysis indicate that the algorithm presented in this paper has more excellent reconstruction performance, as the reconstructed temperature distributions will not lose information near the edge of area while with small errors, and its mean reconstruction time is short enough that can meet the real-time demand.

scholarly journals Truly Distributed Optical Fiber Sensors for Structural Health Monitoring: From the Telecommunication Optical Fiber Drawling Tower to Water Leakage Detection in Dikes and Concrete Structure Strain Monitoring

2010 ◽  
Vol 2010 ◽  
pp. 1-13 ◽  
Author(s):  
Jean-Marie Henault ◽  
Gautier Moreau ◽  
Sylvain Blairon ◽  
Jean Salin ◽  
Jean-Robert Courivaud ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Optical Fibers ◽  
Brillouin Scattering ◽  
Optical Fiber Sensors ◽  
Leakage Detection ◽  
Strain Sensing ◽  
Water Leakage ◽  
Fiber Sensors ◽  
Practical Applications ◽  
Water Leakage Detection

Although optical fiber sensors have been developed for 30 years, there is a gap between lab experiments and field applications. This article focuses on specific methods developed to evaluate the whole sensing chain, with an emphasis on (i) commercially-available optoelectronic instruments and (ii) sensing cable. A number of additional considerations for a successful pairing of these two must be taken into account for successful field applications. These considerations are further developed within this article and illustrated with practical applications of water leakage detection in dikes and concrete structures monitoring, making use of distributed temperature and strain sensing based on Rayleigh, Raman, and Brillouin scattering in optical fibers. They include an adequate choice of working wavelengths, dedicated localization processes, choices of connector type, and further include a useful selection of traditional reference sensors to be installed nearby the optical fiber sensors, as well as temperature compensation in case of strain sensing.

Electrically Assisted Aerosol Reactors using Ring Electrodes

1998 ◽  
Vol 520 ◽  
Author(s):  
H. Briesen ◽  
A. Fuhrmann ◽  
S. E. Pratsinis
Keyword(s):  
Particle Size ◽  
Electric Fields ◽  
Optical Fibers ◽  
Total Production ◽  
Electrical Fields ◽  
Synthesis Of Nanoparticles ◽  
Practical Applications ◽  
Electrically Assisted ◽  
Aerosol Reactors ◽  
Electrostatic Dispersion

ABSTRACTNanostructured materials have distinctly different properties than the bulk because the number of atoms or molecules on their surface is comparable to that inside the particles creating a number of new materials and applications. Despite this potential for nanoparticles, very few practical applications have been developed because of the current high cost of these materials ($100/lb). On the other hand, flame aerosol reactors are routinely used for inexpensive production (∼$1/lb) of submicron sized commodities such as carbon blacks, pigmentary titania, fumed silica and preforms for optical fibers in telecommunications. Flame technology can be used also for synthesis of nanoparticles with precisely controlled characteristics. In these reactors, gas mixing is used to widely control the primary particle size and crystallinity of product powders while electric fields can be used to narrowly control the primary, and aggregate particle size and crystallinity. Here the application of axial electrical fields on a silica producing flame using hexamethyldisiloxane (HMDS) as precursor is presented. Experiments varying the precursor delivery rate corresponding to total production rates of 10, 20 and 30 g/h are presented. Electric fields decreased the particle size by electrostatic dispersion and repulsion of charged particles and by the reduced particle residence time inside the flame.

scholarly journals A Mobile Detector for Muon Measurements Based on Two Different Techniques

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
B. Mitrica ◽  
D. Stanca ◽  
M. Petcu ◽  
I. M. Brancus ◽  
R. Margineanu ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Wave Length ◽  
Light Output ◽  
Environmental Studies ◽  
Muon Flux ◽  
Practical Applications ◽  
Cosmic Muon ◽  
Flux Measurements ◽  
Comparative Results ◽  
Set Up

Precise measurements of the muon flux are important for different practical applications, both in environmental studies and for the estimation of the water equivalent depths of underground sites. A mobile detector for cosmic muon flux measurements has been set up at IFIN-HH, Romania. The device is used to measure the muon flux on different locations at the surface and underground. Its first configuration, not used in the present, has been composed of two 1 m2scintillator plates, each viewed by wave length shifters and read out by two Photomultiplier Tubes (PMTs). A more recent configuration, consists of two 1 m2detection layers, each one including four 1 · 0,25 m2large scintillator plates. The light output in each plate is collected by twelve optical fibers and then read out by one PMT. Comparative results were obtained with both configurations.

Fictive temperature distribution in highly Ge-doped multimode optical fibers

2007 ◽  
Vol 353 (5-7) ◽  
pp. 473-476 ◽  
Author(s):  
M. Lancry ◽  
I. Flammer ◽  
D. Simons ◽  
B. Poumellec ◽  
C. Depecker ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Optical Fibers ◽  
Fictive Temperature

Modeling of Advanced Melting Zone for Manufacturing of Optical Fibers*

2004 ◽  
Vol 126 (4) ◽  
pp. 750-759
Author(s):  
Zhiyong Wei ◽  
Kok-Meng Lee ◽  
Zhi Zhou ◽  
Siu-Ping Hong
Keyword(s):  
Temperature Distribution ◽  
Radiative Transfer ◽  
Optical Fibers ◽  
Feed Rate ◽  
Melting Zone ◽  
Transient Temperature ◽  
Drawing Process ◽  
Fiber Drawing ◽  
Thermally Induced ◽  
Transient Temperature Distribution

Optical fibers are drawn from preforms (fused silica glass rods) typically made up of two concentric cylinders (the core rod and the clad tube), which are usually joined in a separate fusion process. The setup time and hence manufacturing cost can be significantly reduced if the two cylinders can be joined in the same furnace in which the fiber is drawn. A good understanding of the transient temperature distribution is needed for controlling the feed rate to avoid thermally induced cracks. Since direct measurement of the temperature fields is often impossible, the geometrical design of the preform and the control of the feed rate have largely been accomplished by trials-and-errors. The ability to predict the transient temperature distribution and the thermally induced stresses will provide a rational basis to design optimization and feed rate control of the process. In this paper, we present an analytical model to predict the transient conductive-radiative transfer as two partially joined, concentric glass cylinders with specular surfaces are fed into the furnace. Finite volume method (FVM) is used to solve the radiative transfer equation (RTE). The specular surface reflectivity is obtained by the Fresnel’s law and the Snell’s law. The boundary intensities are obtained through the coupling of the interior glass radiative transfer and the exterior furnace enclosure analysis. The model has been used to numerically study the transient conductive-radiative transfer in the advanced melting zone (AMZ) of an optic fiber drawing process. This problem is of both theoretical and practical interest in the manufacture of optical fibers. The computational method for the radiation transfer developed in this paper can also be applied to the simulation of the fiber drawing process and other glass-related manufacturing processes.

Paper 7: The Prediction of Diesel Engine Performance and Combustion Chamber Component Temperatures Using Digital Computers

1967 ◽  
Vol 182 (12) ◽  
pp. 58-70 ◽  
Author(s):  
M. S. Janota ◽  
A. J. Hallam ◽  
E. K. Brock ◽  
S. G. Dexter
Keyword(s):  
Diesel Engine ◽  
Temperature Distribution ◽  
Boundary Conditions ◽  
Combustion Chamber ◽  
Engine Performance ◽  
Practical Applications ◽  
Medium Speed ◽  
Turbo Charger ◽  
Engine Components ◽  
Surrounding Fluid

The development of digital programs for predicting the performance of multi-cylinder, turbo-charged diesel engines, and the temperature distribution in engine components is described. The performance program incorporates the relatively simple ‘filling and emptying’ method, with the turbo-charger compressor and turbine as boundary conditions, to calculate transient gas conditions. In the second part of the paper a description is given of the metal temperature program assumptions and use, including the deduction of the surrounding fluid conditions. The accuracy and limitations of the performance program is demonstrated by comparing predictions and measurements on an experimental 2-stroke single cylinder diesel engine operating under simulated turbo-charged conditions. The practical applications of the programs to medium speed 2- and 4-stroke engines are illustrated, and the economics of their use as a design aid are discussed.

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