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Effect of Lattice Strain on Measured Thermal Properties of Fe Nanoparticles - An X-ray Diffraction Study
Issue:
Volume 5, Issue 3, September 2019
Pages:
63-66
Received:
7 April 2019
Accepted:
19 July 2019
Published:
6 August 2019
Abstract: In this paper, nano Fe particles have been produced by ball milling process. Fe powder was ball milled in an argon inert atmosphere Ball milling was carried out for the total duration of 20 hours. The sample was taken out after every 4 hours of milling and it was characterized for its particle size, lattice strain, and Debye-Waller factor, root mean square amplitudes of vibration by X-ray powder diffraction. The high-energy ball milling of Fe after 20 hours resulted in particle size of 39.44 nm and lattice stain 0.68 Lattice strains in Fe powder produced by milling have been analyzed by X-ray powder diffraction. The lattice strain (e) and Debye-Waller factor (B) are determined from the half-widths and integrated intensities of the Bragg reflections. Debye-Waller factor is found to increase with the lattice strain. From the correlation between the strain and effective Debye-Waller factors have been estimated for Fe. The variation of energy of vacancy formation as a function of lattice strain has been studied. The lattice strain (e) and Debye-Waller factor (B) are determined from the half-widths and integrated intensities of the Bragg reflections. In Fe, the Debye-Waller factor is found to increase with the lattice strain. From the correlation between the strain and effective Debye-Waller factor, the Debye-Waller factors for zero strain have been estimated for Fe. The variation of energy of vacancy formation as a function of lattice strain has been studied. As grinding time increases energy of vacancy formation decreases. However, the milling produces lattice strain and also enhances the effective Debye-Waller factor. By an extrapolation of the plot between the Debye-Waller factor and the lattice strain, the zero strain Debye-Waller factors are obtained for Fe. The variation of energy of vacancy formation as a function of lattice strain has been studied.
Abstract: In this paper, nano Fe particles have been produced by ball milling process. Fe powder was ball milled in an argon inert atmosphere Ball milling was carried out for the total duration of 20 hours. The sample was taken out after every 4 hours of milling and it was characterized for its particle size, lattice strain, and Debye-Waller factor, root mea...
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On Plane Motion of Incompressible Variable Viscosity Fluids with Moderate Peclet Number in Presence of Body Force Via Von-Mises Coordinates
Issue:
Volume 5, Issue 3, September 2019
Pages:
67-74
Received:
13 March 2019
Accepted:
22 July 2019
Published:
10 August 2019
Abstract: The aim of this article is to use von-Mises coordinates to find a class of new exact solutionsof the equations governing the plane steady motion with moderate Peclet number of incompressible fluid of variable viscosity in presence of body force. An equation relating a differentiable function and a stream function characterizes the class under consideration. When the differentiable function is parabolic and when it is not, in both the cases, it finds exact solutions for given one component of the body force. This discourse shows an infinite set of streamlines and the velocity components, viscosity function, generalized energy function and temperature distribution for moderate Peclet number in presence of body force. Moreover, for parabolic case, it obtains viscosity as a function of temperature distribution for moderate Peclet number.
Abstract: The aim of this article is to use von-Mises coordinates to find a class of new exact solutionsof the equations governing the plane steady motion with moderate Peclet number of incompressible fluid of variable viscosity in presence of body force. An equation relating a differentiable function and a stream function characterizes the class under consi...
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On Two-Dimensional Variable Viscosity Fluid Motion with Body Forcefor Intermediate Peclet Number Via von-Mises Coordinates
Issue:
Volume 5, Issue 3, September 2019
Pages:
75-81
Received:
13 March 2019
Accepted:
26 July 2019
Published:
26 August 2019
Abstract: This article uses von-Mises coordinates to present a class of new exact solutions of the system of partial differential equations for the plane steady motion of incompressible fluid of variable viscosity in presence of body forcefor moderate Peclet number. This communication applies successive transformation technique and characterizes streamlines through an equation relating a differentiable function f(x) and a function of stream function. Considering the function of stream function satisfies a specific relation, the exact solutions for moderate Peclet number with body force are determined for given one component of the body force when f(x) takes a specific value and when it is not. In both the cases, it shows an infinite set of streamlines, the velocity components, viscosity function, generalized energy function and temperature distribution for intermediate Peclet number in presence of body force. When f(x) takes a specific value, a relation between viscosity and temperature function is observed.
Abstract: This article uses von-Mises coordinates to present a class of new exact solutions of the system of partial differential equations for the plane steady motion of incompressible fluid of variable viscosity in presence of body forcefor moderate Peclet number. This communication applies successive transformation technique and characterizes streamlines ...
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Research on Flow Characteristics of Upstream Cavity with Labyrinth Seals in Axial Compressor
Xin Fu,
Yingying Xu,
Yan Zhang
Issue:
Volume 5, Issue 3, September 2019
Pages:
82-90
Received:
13 July 2019
Accepted:
10 September 2019
Published:
23 September 2019
Abstract: The sealing between rotating components and stator components has become one of the main issues to be studied in the compressor. The mixing of stator root leakage flow and the mainstream can seriously affect the performance of the compressor. This article does a series of work on numerical calculation of plane diffuser cascade with the stator cavity and three-stage labyrinth seal. It also analyzes the details of the flow structure on upstream cavity. In this paper, the 3D streamlines distribution of the cascade corner region is studied, respectively for the no leakage case and the mixing mechanism of the secondary flow and mainstream with leakage. On this basis, the upstream cavity configuration is optimized and some results are obtained as fellows. The mainstream in the blade leading edge into the upstream cavity comes into being the secondary flow, which similar to leakage flow. It can affect the highest 80% leaves of the high range. Leakage flow is mainly influence on the performance of the blade root flow field and weakly of next to casing area. Compared to no leakage case, angular separation position ahead of time and range increased when there is leakage. Thus, added rib on both sides of the vessel wall can reduce the total pressure loss of the S3 section, and the relative position of ribbed effect significantly. The research shows that first layer of rib is better when set on the hub wall surface, the total pressure loss coefficient decreased by 3.49%.
Abstract: The sealing between rotating components and stator components has become one of the main issues to be studied in the compressor. The mixing of stator root leakage flow and the mainstream can seriously affect the performance of the compressor. This article does a series of work on numerical calculation of plane diffuser cascade with the stator cavit...
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