Boundary Layers Refractory/Glass Melt and Glass Defects

2008 ◽  
Vol 39-40 ◽  
pp. 601-606 ◽  
Author(s):  
Michael Dunkl
Keyword(s):  
Boundary Layer ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Boundary Layers ◽  
Corrosion Behaviour ◽  
The Other ◽  
Glass Melts ◽  
Good Corrosion Resistance ◽  
Protection Layer ◽  
The One

In this paper the formation of boundary layers and their behaviour regarding corrosion and glass defect potential of different refractory/glass melt combinations will be discussed. The reaction between refractories and glass melts is determined by the diffusion of the different ions from the glass melt into the refractory material and vice versa. The connected solution reactions lead to the formation of a saturation boundary layer, which influences the corrosion behaviour and the glass defect potential. The behaviour of the boundary layers of various refractory/glass melt types are partly complete different. On the one side there are refractory/glass melt combinations which form a relative thick reaction layer, on the other side there are refractory/glass melt combinations with very thin boundary layers. Thick reaction layers affect in the most cases like a protection layer with a good corrosion resistance, but there can be a relative high glass defect potential at operation changes. Thin reaction layers have for the most cases a low glass defect potential, but partly a higher corrosion rate.

CLC 18.10LN

Alloy Digest ◽  
2006 ◽  
Vol 55 (1) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Shear Strength ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Stainless Steels ◽  
The Other ◽  
Low Carbon ◽  
Good Corrosion Resistance ◽  
Temperature Performance

Abstract CLC 18.10LN is an austenitic stainless steel with 18% Cr, 9.5% Ni, and 0.14% N to provide good corrosion resistance at strengths above the other low-carbon stainless steels. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and shear strength as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, machining, and joining. Filing Code: SS-950. Producer or source: Industeel USA, LLC.

An example of steady laminar flow at large Reynolds number

1960 ◽  
Vol 9 (4) ◽  
pp. 593-602 ◽  
Author(s):  
Iam Proudman
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Boundary Layers ◽  
Tangential Velocity ◽  
Fluid Flows ◽  
The Other ◽  
Large Reynolds Number ◽  
Rotational Flows ◽  
Flow Domain ◽  
Source Of Information

The purpose of this note is to describe a particular class of steady fluid flows, for which the techniques of classical hydrodynamics and boundary-layer theory determine uniquely the asymptotic flow for large Reynolds number for each of a continuously varied set of boundary conditions. The flows involve viscous layers in the interior of the flow domain, as well as boundary layers, and the investigation is unusual in that the position and structure of all the viscous layers are determined uniquely. The note is intended to be an illustration of the principles that lead to this determination, not a source of information of practical value.The flows take place in a two-dimensional channel with porous walls through which fluid is uniformly injected or extracted. When fluid is extracted through both walls there are boundary layers on both walls and the flow outside these layers is irrotational. When fluid is extracted through one wall and injected through the other, there is a boundary layer only on the former wall and the inviscid rotational flow outside this layer satisfies the no-slip condition on the other wall. When fluid is injected through both walls there are no boundary layers, but there is a viscous layer in the interior of the channel, across which the second derivative of the tangential velocity is discontinous, and the position of this layer is determined by the requirement that the inviscid rotational flows on either side of it must satisfy the no-slip conditions on the walls.

Annulus Wall Boundary-Layer Measurements in a Four-Stage Compressor

1986 ◽  
Vol 108 (1) ◽  
pp. 2-6 ◽  
Author(s):  
N. A. Cumpsty
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Layer Thickness ◽  
Boundary Layers ◽  
Boundary Layer Thickness ◽  
Tip Clearance ◽  
The Other ◽  
Wall Boundary Layer ◽  
Multistage Compressors ◽  
Full Design

There are few available measurements of the boundary layers in multistage compressors when the repeating-stage condition is reached. These tests were performed in a small four-stage compressor; the flow was essentially incompressible and the Reynolds number based on blade chord was about 5 • 104. Two series of tests were performed; in one series the full design number of blades were installed, in the other series half the blades were removed to reduce the solidity and double the staggered spacing. Initially it was wished to examine the hypothesis proposed by Smith [1] that staggered spacing is a particularly important scaling parameter for boundary layer thickness; the results of these tests and those of Hunter and Cumpsty [2] tend to suggest that it is tip clearance which is most potent in determining boundary-layer integral thicknesses. The integral thicknesses agree quite well with those published by Smith.

scholarly journals Effect of Additives on Electrodeposition of Zinc-Nickel Alloy On Mild Steel

2019 ◽  
Vol 31 (4) ◽  
pp. 891-895
Author(s):  
Dinesh Kumar Chelike ◽  
K. Juliet Gnana Sundari
Keyword(s):  
Corrosion Resistance ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Alloy Coating ◽  
Complexing Agent ◽  
Tafel Polarization ◽  
Good Corrosion Resistance ◽  
Ni Alloy ◽  
Strong Candidate

Considering the good corrosion resistance of Zn-Ni alloy, it is selected in the present study to be the protective coating on mild steel and it is considered as a strong candidate for the replacement of environmentally hazardous cadmium. Zn-Ni alloy coating is applied by electrodeposition at optimum temperature, current density and time. The bath solution used is consisting of EDTA as complexing agent. The electrodeposition is also carried out with tartaric acid and benzaldehyde additives to have good corrosion resistance and brightness. The electrodeposits obtained with and without additives are examined for nature and alloy composition. The corrosion behaviour of the electrodeposits is studied by Tafel polarization and electrochemical impedance spectroscopy.

Analysis of the Sutton Model for Aero-Optical Properties of Compressible Boundary Layers

2005 ◽  
Vol 128 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Eric Tromeur ◽  
Eric Garnier ◽  
Pierre Sagaut
Keyword(s):  
Boundary Layer ◽  
Density Field ◽  
The Other ◽  
Navier Stokes ◽  
Eddy Simulation ◽  
Compressible Boundary Layers ◽  
Optical Effects ◽  
Large Eddy ◽  
The One ◽  
Reference Tool

In order to assess the capability of the Sutton model to evaluate aero-optical effects in a turbulent boundary layer, large-eddy simulation (LES) evolving spatially and Reynolds averaged Navier-Stokes (RANS) computations are carried out at Mach number equal to 0.9. First aerodynamic fields are proved to compare favorably with theoretical and experimental results. Once validated, the characteristics of the boundary layer allow us to obtain information concerning optical beam degradation. On the one hand, the density field is used to compute phase distortion directly and, on the other hand, by means of the Sutton model. Therefore, LES and RANS simulations allow us to study optical models and the validity of their assumptions. Finally, LES is proved to be considered as a reference tool to evaluate aero-optical effects.

scholarly journals Effect of Minor Alloying Elements on the Corrosion Behavior of Fe40Al in NaCl-KCl Molten Salts

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
G. Salinas ◽  
J. G. Gonzalez-Rodriguez ◽  
J. Porcayo-Calderon ◽  
V. M. Salinas-Bravo ◽  
M. A. Espinoza-Medina
Keyword(s):  
Weight Loss ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Molten Salts ◽  
Electrochemical Techniques ◽  
The Other ◽  
Type Stainless Steel ◽  
Waste Gasification

The hot corrosion behavior of Fe40Al intermetallic alloyed with Ag, Cu, Li, and Ni (1–5 at.%) in NaCl-KCl (1 : 1 M) at 670°C, typical of waste gasification environments, has been evaluated by using polarization curves and weight loss techniques and compared with a 304-type stainless steel. Both gravimetric and electrochemical techniques showed that all different Fe40Al-base alloys have a much higher corrosion resistance than that for stainless steel. Among the different Fe40Al-based alloys, the corrosion rate was very similar among each other, but it was evident that the addition of Li decreased their corrosion rate whereas all the other elements increased it. Results have been explained in terms of the formation and stability of an external, protective Al2O3layer.

scholarly journals On the identification of well-behaved turbulent boundary layers

2017 ◽  
Vol 822 ◽  
pp. 109-138 ◽  
Author(s):  
C. Sanmiguel Vila ◽  
R. Vinuesa ◽  
S. Discetti ◽  
A. Ianiro ◽  
P. Schlatter ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Velocity Profile ◽  
Skin Friction ◽  
Boundary Layers ◽  
Shape Factor ◽  
Outer Region ◽  
The Other ◽  
Diagnostic Plot ◽  
Other Hand

This paper introduces a new method based on the diagnostic plot (Alfredsson et al., Phys. Fluids, vol. 23, 2011, 041702) to assess the convergence towards a well-behaved zero-pressure-gradient (ZPG) turbulent boundary layer (TBL). The most popular and well-understood methods to assess the convergence towards a well-behaved state rely on empirical skin-friction curves (requiring accurate skin-friction measurements), shape-factor curves (requiring full velocity profile measurements with an accurate wall position determination) or wake-parameter curves (requiring both of the previous quantities). On the other hand, the proposed diagnostic-plot method only needs measurements of mean and fluctuating velocities in the outer region of the boundary layer at arbitrary wall-normal positions. To test the method, six tripping configurations, including optimal set-ups as well as both under- and overtripped cases, are used to quantify the convergence of ZPG TBLs towards well-behaved conditions in the Reynolds-number range covered by recent high-fidelity direct numerical simulation data up to a Reynolds number based on the momentum thickness and free-stream velocity $Re_{\unicode[STIX]{x1D703}}$ of approximately 4000 (corresponding to 2.5 m from the leading edge) in a wind-tunnel experiment. Additionally, recent high-Reynolds-number data sets have been employed to validate the method. The results show that weak tripping configurations lead to deviations in the mean flow and the velocity fluctuations within the logarithmic region with respect to optimally tripped boundary layers. On the other hand, a strong trip leads to a more energized outer region, manifested in the emergence of an outer peak in the velocity-fluctuation profile and in a more prominent wake region. While established criteria based on skin-friction and shape-factor correlations yield generally equivalent results with the diagnostic-plot method in terms of convergence towards a well-behaved state, the proposed method has the advantage of being a practical surrogate that is a more efficient tool when designing the set-up for TBL experiments, since it diagnoses the state of the boundary layer without the need to perform extensive velocity profile measurements.

scholarly journals Effect of Sr and Ti Addition on the Corrosion Behaviour of Al-7Si-0.3Mg Alloy

2017 ◽  
Vol 17 (2) ◽  
pp. 125-130 ◽  
Author(s):  
M. Uludağ ◽  
M. Kocabaş ◽  
D. Dışpınar ◽  
R. Çetin ◽  
N. Cansever
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Potentiodynamic Polarization ◽  
Corrosion Test ◽  
Corrosion Behaviour ◽  
Tensile Tests ◽  
Nacl Solution ◽  
Cyclic Potentiodynamic Polarization ◽  
Ti Addition

AbstractIn the present study, the corrosion behaviour of A356 (Al-7Si-0.3Mg) alloy in 3.5% NaCl solution has been evaluated using cyclic/potentiodynamic polarization tests. The alloy was provided in the unmodified form and it was then modified with AlTi5B1 for grain refinement and with AlSr15 for Si modifications. These modifications yield to better mechanical properties. Tensile tests were performed. In addition, bifilm index and SDAS values were calculated and microstructure of the samples was investigated. As a result of the corrosion test, the Ecorr values for all conditions were determined approximately equal, and the samples were pitted rapidly. The degassing of the melt decreased the bifilm index (i.e. higher melt quality) and thereby the corrosion resistance was increased. The lowest corrosion rate was founded at degassing and as-received condition (3.9x10-3mm/year). However, additive elements do not show the effect which degassing process shows.

scholarly journals A Three-Step Method for Estimating the Mixing Height Using Ceilometer Data from the Helsinki Testbed

2012 ◽  
Vol 51 (12) ◽  
pp. 2172-2187 ◽  
Author(s):  
Noora Eresmaa ◽  
Jari Härkönen ◽  
Sylvain M. Joffre ◽  
David M. Schultz ◽  
Ari Karppinen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Vertical Profile ◽  
The Other ◽  
Vertical Profiles ◽  
Backscattering Coefficient ◽  
Mixing Height ◽  
Step Method ◽  
Profile Method ◽  
One Step ◽  
The One

AbstractA new three-step idealized-profile method to estimate the mixing height from vertical profiles of ceilometer backscattering coefficient is developed to address the weaknesses found with such estimates that are based on the one-step idealized-profile method. This three-step idealized-profile method fits the backscattering coefficient profile of ceilometer measurements into an idealized scaled vertical profile of three error functions, thus having the potential to determine three aerosol layers (one for the surface layer, one for the mixing height, and one for the artificial layer caused by the weakened signal). This three-step idealized-profile method is tested with ceilometer and radiosounding data collected during the Helsinki Testbed campaign (2 January 2006–13 March 2007). Excluding cases with low aerosol concentration in the boundary layer, cases with clouds present, and cases with precipitation present, the resulting dataset consists of 97 simultaneous backscattering coefficient profiles and radiosoundings. The three-step method is compared with the one-step method and other commonly employed algorithms. A strong correlation (correlation coefficient r = 0.91) between the mixing heights as determined by the three-step method using ceilometer data and those determined from radiosoundings is an improvement over the same correlation using the one-step method (r = 0.28), as well as the other algorithms.

Corrosion Behaviour of Structural Ceramics in Supercritical Water

2006 ◽  
Vol 45 ◽  
pp. 173-177 ◽  
Author(s):  
Masahiro Nagae ◽  
Tetsuo Yoshio ◽  
Kohei Oda
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Supercritical Water ◽  
Intergranular Corrosion ◽  
Corrosion Behaviour ◽  
Impurity Content ◽  
Amorphous Layer ◽  
Structural Ceramics ◽  
Alumina Ceramics

The corrosion behavior of Si3N4, SiC, mullite, alumina and sapphire was investigated in supercritical water at 450 °C and 45MPa for 2 to 50h. Corrosion resistance for the ceramics was as follows in the order; Si3N4 < SiC < mullite < alumina < sapphire. Pitting corrosion with formation of amorphous layer and intergranular corrosion due to dissolution of additives were observed in PLS-Si3N4 and PLS-SiC, respectively. The corrosion behavior of mullite was characterized by dissolution of SiO2 and formation of boehmite residue layer. High purity alumina ceramics showed the highest corrosion resistance in the ceramics. Intergranular corrosion proceeded in the alumina ceramics and its corrosion rate was strongly dependent on the impurity content.

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