The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
C S Shin - One of the best experts on this subject based on the ideXlab platform.
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evaluating fatigue crack propagation properties using a Cylindrical Rod specimen
International Journal of Fatigue, 2007Co-Authors: C S ShinAbstract:In the evaluation of fatigue crack propagation properties, standard specimens such as the compact tension (CT) or center cracked specimens are commonly employed. However, these specimens are not applicable when the available material for testing is of a long axial length but small cross-sectional area. Surface cracked Rod specimens may be used for this purpose. In the current work, to shed light on their applicability to the evaluation of fatigue crack propagation properties, surface cracked Rod specimens were tested under axial tension. The development of the surface cracks was examined. Fatigue crack propagation data at the surface and in the deepest interior point of the surface cracks in different diameter Rods were obtained. Comparison showed that Rods with diameters of 8 mm and larger give fatigue crack propagation data similar to that given by compact tension specimens. For a 6 mm diameter Rod specimen, growth rates were slightly higher than the standard if correlated in terms of ΔK but, fall in line with the standard, if crack closure was taken into account.
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a normalized area compliance method for monitoring surface crack development in a Cylindrical Rod
International Journal of Fatigue, 2005Co-Authors: C S ShinAbstract:A Normalized Area-compliance method has been shown to be able to predict the depth of an elliptical surface crack in a Cylindrical Rod. The method involves a combination of optical surface crack length measurement and specimen compliance measurement. Finite element analysis was employed to show that the specimen compliance has a one-to-one correspondence with the Normalized Area (NA) or Normalized Harmonic Mean Radius (NHMR) independent of crack depth and crack aspect ratio and with the crack shape and specimen dimension for a range of crack and specimen dimensions. Based on the finite element analysis, master curves of Normalized Compliance versus Normalized Area have been generated for surface-cracked Rod under tension with ends free or constrained from rotation. The accuracy of crack depth prediction using this method has been verified by fractography of fatigue cracked Rods. Moreover, fatigue crack growth behaviour deduced from this crack depth measurement agrees well with the crack growth data obtained from the standard compact tension specimen.
Minho Bang - One of the best experts on this subject based on the ideXlab platform.
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effect of the wake on the heat transfer of a turbine blade endwall according to relative position of the Cylindrical Rod
International Communications in Heat and Mass Transfer, 2018Co-Authors: Seok Min Choi, Minho BangAbstract:Abstract In a turbine passage, the wake, which affects the heat transfer of a turbine blade, occurs periodically due to rotation of the blade. We analyzed the effect of wake on the endwall of the turbine blade according to the relative position of the turbine blade and the vane in a stationary condition. The naphthalene sublimation method was used to measure the heat transfer and detached eddy simulation (DES) was used to analyze flow characteristics. The wake from the vane was simulated by using a Cylindrical Rod upstream of the blade. The Cylindrical Rod was placed in four which positions that were aligned leading edge-to‑leading edge. The pressure and Q criterion distributions varied according to the position of the upstream wake. As the position of the upstream wake changed, the point at which the passage vortex and wake met varied. Wake and passage vortex met at x/Cx = 0.2 in position 1 and at x/Cx = 0.55 in position 2. After the wake and passage vortex had met, the secondary flow scattered. Therefore, the local and averaged heat transfer varied due to flow characteristics. Thus designers of film cooling holes on endwalls should consider these effects to ensure appropriate cooling performance.
L P H De Goey - One of the best experts on this subject based on the ideXlab platform.
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structure and stability of premixed flames stabilized behind the trailing edge of a Cylindrical Rod at low lewis numbers
Proceedings of the Combustion Institute, 2015Co-Authors: V N Kurdyumov, Yuriy Shoshin, L P H De GoeyAbstract:Premixed flames stabilized behind the trailing edge of a semi-infinite Cylindrical Rod placed coaxially in a circular channel were investigated numerically within the diffusive-thermal model. Apart from the inverted flames, or V-flames, widely reported in the literature, the other kind of flames was observed for the Lewis number lower than unity. The main characteristic of such flames is confinement in the interior of a recirculating vortex formed behind the trailing edge. For a fixed Reynolds number, the flames of this kind exist within a finite range of the Damkohler number. Once the Damkohler number is fixed, they are observed for the Reynolds numbers above a critical value with no limit on large Re, assuming that flow remains laminar. Global linear stability analysis of the axisymmetric steady-state solutions of both kinds was performed. The ranges of the parameters where the axisymmetry-breaking bifurcation arises and the oscillatory behavior takes place were found. The results of the stability analysis were successfully compared with the direct two- and three-dimensional numerical simulations.
Seok Min Choi - One of the best experts on this subject based on the ideXlab platform.
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effect of the wake on the heat transfer of a turbine blade endwall according to relative position of the Cylindrical Rod
International Communications in Heat and Mass Transfer, 2018Co-Authors: Seok Min Choi, Minho BangAbstract:Abstract In a turbine passage, the wake, which affects the heat transfer of a turbine blade, occurs periodically due to rotation of the blade. We analyzed the effect of wake on the endwall of the turbine blade according to the relative position of the turbine blade and the vane in a stationary condition. The naphthalene sublimation method was used to measure the heat transfer and detached eddy simulation (DES) was used to analyze flow characteristics. The wake from the vane was simulated by using a Cylindrical Rod upstream of the blade. The Cylindrical Rod was placed in four which positions that were aligned leading edge-to‑leading edge. The pressure and Q criterion distributions varied according to the position of the upstream wake. As the position of the upstream wake changed, the point at which the passage vortex and wake met varied. Wake and passage vortex met at x/Cx = 0.2 in position 1 and at x/Cx = 0.55 in position 2. After the wake and passage vortex had met, the secondary flow scattered. Therefore, the local and averaged heat transfer varied due to flow characteristics. Thus designers of film cooling holes on endwalls should consider these effects to ensure appropriate cooling performance.
V N Kurdyumov - One of the best experts on this subject based on the ideXlab platform.
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structure and stability of premixed flames stabilized behind the trailing edge of a Cylindrical Rod at low lewis numbers
Proceedings of the Combustion Institute, 2015Co-Authors: V N Kurdyumov, Yuriy Shoshin, L P H De GoeyAbstract:Premixed flames stabilized behind the trailing edge of a semi-infinite Cylindrical Rod placed coaxially in a circular channel were investigated numerically within the diffusive-thermal model. Apart from the inverted flames, or V-flames, widely reported in the literature, the other kind of flames was observed for the Lewis number lower than unity. The main characteristic of such flames is confinement in the interior of a recirculating vortex formed behind the trailing edge. For a fixed Reynolds number, the flames of this kind exist within a finite range of the Damkohler number. Once the Damkohler number is fixed, they are observed for the Reynolds numbers above a critical value with no limit on large Re, assuming that flow remains laminar. Global linear stability analysis of the axisymmetric steady-state solutions of both kinds was performed. The ranges of the parameters where the axisymmetry-breaking bifurcation arises and the oscillatory behavior takes place were found. The results of the stability analysis were successfully compared with the direct two- and three-dimensional numerical simulations.
