Application of Innovative Cost effective flow resistivity measurement system for Acoustic Performance Analysis of Natural fibers

In design of the interior of car, workplace and companies, acoustic material plays very important role. To attenuate unwanted noise, passive noise control technique using acoustic material is used extensively. The non-biodegradable synthetic acoustic material, which are used nowadays cause environmental pollution. This environmental pollution motivates researchers to find eco-friendly and sustainable acoustic materials as an alternative sound absorber. Research is going on to find new acoustic materials for many industrial and domestic applications. The value of sound absorption coefficient has correlation with frequency of sound. Hence, it would be very helpful if the characteristic acoustic properties of these materials are known prior using them for a particular application. This paper presents the utilization of new flow resistivity measurement set up. This flow resistivity set up is developed as per ASTM C522-03 standard. Delany-Bazley model can be used to predict sound absorption coefficient using flow resistivity values. The numerical analysis using MATLAB program based on Delany-Bazley models is made to determine sound absorption coefficient of material prepared from natural fibers of sugarcane waste, wheat straw and PU foam, Glass wool. The sound absorption coefficients of all four materials are also obtained by experimental investigation using impedance tube as per ASTM E 1050 standard. Comparisons of the experimental and the numerical results confirm that the sound absorption coefficients of all material are well corroborated

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