Experimental Analysis of different shaped ribs on heat transfer and fluid flow characteristics

There are number of applications such as gas turbines, solar air heating, electronics cooling and heat exchangers, where internal cooling passage is observed. For heat transfer augmentation inside these cooling passages different techniques are used like dimpled surface, wings and ribs. Ribs are used in most of the devices for internal cooling. The ribs disturb the boundary layer and increase the turbulent kinetic energy which enhances the heat transfer rate. Most of the researchers concentrate on square and rectangular shaped ribs. The cross section of the rib plays important role in the production of flow field. The shape of ribs affects on boundary layer separation, attachment and hot spots created. In the present paper heat transfer and fluid flow characteristics from rib roughened rectangular duct with different shapes of ribs were investigated. The experimental set up consists of rectangular channel of aspect ratio 4. The pitch to width ratio was varied as 5, 7.5 and 10 respectively. The Reynolds number was varied as 6000 to 30000. The ribs used for the investigations were square, house and boot shaped. From the investigations it is observed that boot shaped rib is having higher thermal performance than other two geometrie

The influence of coolant on tool deterioration of uncoated carbide tools in endmilling hardened inconel 718plus nickel based superalloy

Acritical reviewhas been carried out in the literature in order to investigate the impact of the coolant in machining hardened nickel-based superalloy; however little has been found. The increase in strength of a workpiece material generates a high cutting force during the material removal process, therefore reduce the tool life. As a result of limited knowledge addressing the role of coolant in enhancing the life of the cutting tool, this research intends to investigate the influence of coolant on tool deterioration of a hardened nickel-based superalloy. Milling experiments were conducted a hardened state of Inconel 718Plus nickel-based superalloy with uncoated carbide tools in dry and wet conditions. Experimental results showed that on average, both dry and wet conditions allowed for four passes (Npass) before the end of tool life