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Full-Text Articles in Mechanical Engineering
Aerodynamic Performance And Shedding Characteristics On A Swept-Back Wing, Shun-Chang Yen
Aerodynamic Performance And Shedding Characteristics On A Swept-Back Wing, Shun-Chang Yen
Journal of Marine Science and Technology
A NACA 0012 finite swept-back wing with a sweep-back angle of 15° was utilized to investigate the effects of angle of attack (α) and the chord Reynolds number (Rec) on the vortex shedding and aerodynamic coefficients. A hot-wire anemometer was applied to measure the vortex-shedding frequency. The projected Strouhal number (Std) at various angles of attack was determined and discussed. The relationship between Std and α is regressed as: Std = -0.0008 α + 0.209, for 22° < α < 90°. Four characteristic surface-flow patterns: separation bubble, leading-edge bubble, bubble burst, and turbulent separation were classified by changing α and Re. The behavior of surface-flow structures significantly affects the lift, drag, and moment coefficients. The lift coefficient (CL) increases with α in the separation bubble and leading-edge bubble regimes. The maximum increase rate of CL with respect to α (d(CL)/dα) is 1.52 π/rad. Occurring in the leadingedge bubble regime. However, the maximum increase rate of drag coefficient (CD) with respect to α (d(CD)/dα) is 0.49 π/rad. Occurring in the bubble-burst regime. The steep-drop of moment coefficient at stall in the unswept-wings is not observed in the swept-back wings.
Dislocation Substructures Of Interstitial-Free Steel Subjected To Low Cycle Fatigue At Various Strain Amplitude, Shih-Wei Mao, Wen-Chun Lo, Hsing-Lu Huang, New-Jin Ho
Dislocation Substructures Of Interstitial-Free Steel Subjected To Low Cycle Fatigue At Various Strain Amplitude, Shih-Wei Mao, Wen-Chun Lo, Hsing-Lu Huang, New-Jin Ho
Journal of Marine Science and Technology
The aim of this wok is to study the fatigue properties in relation to the microstructures of interstitial-free (IF) steel, a representative of body center cubic (BCC) materials, subjected to low cycle periodic stress. In order to compare the grain size effect on dislocation development, we used samples of two distinctive grain sizes, 70 µm and 210 µm, prepared by different thermo-mechanical processes. We found (1) there was an initial softening when the stain amplitude was lower than 1.6% and the microstructure of the fatigued samples are cellular independent of the grain sizes and the amplitude of strain. (2) A …
Deformation Of Rolling Shutters Under Uniform Wind Pressure, Nan-Nong Huang, San-Ming Chang
Deformation Of Rolling Shutters Under Uniform Wind Pressure, Nan-Nong Huang, San-Ming Chang
Journal of Marine Science and Technology
In this study, a model is developed to analyze the structural behaviors of rolling shutters subjected to wind pressure. In the current shutter theory, the elastic properties of shutters are characterized by two bending rigidities, which can be determined from the flexural tests of slats and shutters. Close form solutions can be obtained for the deflection of shutters with two opposite simply supported edges. To assess the validity of the present theory, rolling shutters with various sizes and supporting conditions under various magnitudes of loadings are tested. It is noted that the deflections and axial displacements based on the current …
Hydrogen Absorption/Desorption In A Metal Hydride Reactor Accounting For Varied Effective Thermal Conductivity, Chih-Yuan Wang, Hwa-Chong Tien, San-Der Chyou, Nang-Nong Huang, Shing-Hoa Wang
Hydrogen Absorption/Desorption In A Metal Hydride Reactor Accounting For Varied Effective Thermal Conductivity, Chih-Yuan Wang, Hwa-Chong Tien, San-Der Chyou, Nang-Nong Huang, Shing-Hoa Wang
Journal of Marine Science and Technology
This paper investigates the effect of varied effective thermal conductivity on the hydrogen absorption/desorption in a metal hydride (MH) reactor. The effective thermal conductivity of a metal hydride bed was measured by performing steady-state experiment and then compared with the results obtained by employing an existing model. Good agreement was found. Next, numerical simulation on the performance of hydrogen absorption/desorption of the MH reactor was conducted by assuming either varied or constant effective thermal conductivity. Corresponding hydrogen absorption/desorption experiment was performed for comparison. It was found that numerical simulation accounting for varied effective thermal conductivity agrees with the experimental data …