Free vibration response of the single-walled carbon nanotubes (SWCNTs) is investigated using molecular dynamics simulation. Vibrational analysis is performed to study the effects of various defect parameters such as aspect ratio, chirality, presence of vacancy defects, numbers of defects and their position along the length of the SWCNT. The effects of these features on the natural vibration of SWCNTs are studied by determining the change in fundamental natural frequencies due to these features. Dynamics simulations are performed for cantilever boundary condition. Vibrational response obtained through molecular dynamic simulations indicates that shorter tubes offer higher vibrational sensitivity. Chirality effect is found to diminish with the increase in the length of tube. It is also found that the number of defects and their position along the tube affect greatly the natural frequency of the SWCNT. This study will provide invaluable input to the designers and users of carbon nanotube in the field of high-sensitive sensor application.
In the present work, a three-dimensional numerical analysis of multi-hole film cooling on an adiabatic flat plate with combined backward and forward injection holes is carried out at varying velocity ratios from 0.5 to 2.5. The effect of three different multi-hole arrangements, square-diamond, long-diamond, and super-long-diamond with constant perforated percentage (3.27%), on film cooling performance is studied. Combining backward and forward injection holes help in achieving higher velocity boundary layer thickness in the multi-hole arrangement. It is observed that super-long-diamond arrangement provides the highest film cooling effectiveness than square-diamond and long-diamond arrangements and favours early development of coolant film layer.
Present work describes the experimental analysis of unsteady state heat transfer of different solid geometries. Heat transfer process in considered as a function of time only i.e. solid body behave as ‘Lumped’ means there is uniform temperature with in the body and having negligible internal thermal conduction resistance. The lumped analysis is done with cylindrical, conical and mixed geometry of cylinder and cone of two different materials. Specimens are heated in water ant cooled in air to estimate the heat transfer response of geometries in same ambient conditions MATLAB programming is done for calculation to obtain good and accurate results and to estimate heat transfer response of different geometries used in many engineering application.
Characteristics of full coverage film cooling of an adiabatic flat plate are studied for opposite injection of coolant at different angles. Two in-line adjacent rows of cooling holes injecting in opposite directions are considered in this study. The cooling performance is compared with the configurations having forward and reverse injecting holes at similar injection angles. The holes are arranged in an array of 20 rows with equal spacing both span-wise and stream-wise. Computational analyses are carried out over a wide range of velocity ratios (VR) of practical importance ranging from 0.5 to 2.0 at density ratio of about 1.0. Injection angle and velocity ratio are found to have strong influence on film cooling effectiveness of opposite injection. At low velocity ratio of VR=0.5, film cooling performance of opposite injection at 45° is found better than at other angles, i. e. 30° and 60°. At higher velocity ratios, injection at 30° is found superior. Film cooling effectiveness becomes insensitive to velocity ratios at higher range for 45° and 60° injections. Evolution of effusion film layer and interaction between coolant and primary flow is also studied in this paper.
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