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A 3D numerical analysis on an adiabatic flat plate for multi-hole trench cooling with forward, backward and mixed injection holes is performed in the current investigation. The numerical setup is validated before the performances of different cooling configurations are compared. The effect of three different multi-hole trench arrangements, square-diamond, long-diamond, and super-long-diamond with constant perforated percentage (3.27%), on film cooling performance is studied at blowing ratio 1.0. The row-to-row interaction between coolant jets and mainstream is analysed, and lateral film cooling effectiveness is calculated downstream. The dimensionless temperature contour overlaid with streamlines concluded that the SLD trench hole arrangement with forward injection forms a developed effusion layer due to counter-rotating vortex pairs, which helps in proper mixing of coolant jets into the mainstream and improves film cooling effectiveness in lateral as well as in longitudinal direction. It is observed that super-long-diamond arrangement with forward injection provides the highest film cooling effectiveness than square-diamond and long-diamond arrangements and favours early development of the coolant film layer. [ABSTRACT FROM AUTHOR]

The present study performed a three-dimensional numerical analysis on an adiabatic flat plate with forward injection holes for multi-zone film cooling. The cooling holes were divided into three-zone, and the cold air was supplied from cylindrical holes at a velocity ratio of 0.5 and 1.5 with 30° inclination to the primary flow. The effect of multi-zone arrangement in film cooling effectiveness is studied, and a comparison between two-zone and three-zone arrangement has been made. Results show that the three-zone arrangement helps achieve better film cooling effectiveness than the two-zone arrangement due to the uniform flow of coolant at a higher velocity ratio. It also reduces the mass flow rate of secondary flow by decreasing the number of cylindrical holes in the perforated plate. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Artillery projectile 155mm high explosive (HE) extended range full bore boat tail (ERFB BT) and its components experience a high pressure loading of the propellant during gun launch. Mechanical properties of an engineering material are measured using quasi-static tensile test at room temperature. The materials of the projectile and its components are expected to survive time dependent propellant pressure loading inside the gun, which lasts for few microseconds. To investigate dynamic mechanical properties of the projectile and its components at medium strain rates and elevated temperature, the experimental analysis is undertaken. This research paper aims to examine the effect of medium strain rates and elevated temperatures on flow properties of the materials used in the projectile. The uniaxial tensile tests at the medium strain rates between 0.01 s-1 to 1 s-1 and at elevated temperatures ranging between 150 °C to 500 °C are performed separately. The Considére criterion was applied to evaluate strain hardening exponent of the materials. Values of strain hardening exponents of shell body and boat tail materials are less than that of driving band material. Strain rate sensitivity of the materials is observed to be very low, thus indicating a good resistance to plastic deformation. The yield strength and true yield strength of the materials fall with increase in temperature. [ABSTRACT FROM AUTHOR]

The igniter in the rocket motor is used to give sustained combustion to the propellant. This research paper focused on experimental and numerical investigation of effect of the igniter mass on the maximum pressure rise in single grain solid propellant rocket motor. Experiments are carried out with varying igniter mass by approximately ±15 % of calculated igniter mass. The experimental results are in good agreement and compared with numerical results. A linear relationship between igniter mass and maximum pressure is also established numerically. The present investigation reveals that, the igniter mass contributes in maximum pressure rise along with propellant. The maximum pressure can be retained within required range by optimizing the igniter mass for safe working with rocket motor. [ABSTRACT FROM AUTHOR]

Incorporation of fine nanoparticles and cationic surfactant (Aliquat 336) within an ENi–P matrix has given a new dimension to the field of nanocomposite coatings. It describes the surface engineering processes currently used for the protection of AZ91 magnesium alloy surface against wear, including electroless nano-composite coatings. The present work aims to investigate the influence of Aliquat 336 cationic surfactant on the microhardness and tribological properties of electroless (Ni–P–ZnO) ternary alloy nanocomposite coatings on AZ91 magnesium alloy substrate from acidic bath. The results revealed that there was a significant improvement in the microhardness and wear resistance of the coated surface by the addition of cationic surfactant at a concentration of 1.5 g/L as compared to the coating obtained without the addition of cationic surfactant in the chemical bath. These results are thus clearly indicative of the fact that the component of life of members made from substrate subjected to nanocomposite coatings with varying the concentration of surfactant can be greatly improved, thereby preventing early or regular failures, and increasing service life. [ABSTRACT FROM AUTHOR]