NOPR Collection:

Flow resistance network analysis of the back-pressure of automotive mufflers

2013-11-09T16:32:43Z

Title: Flow resistance network analysis of the back-pressure of automotive mufflers Authors: Munjal, M L; Vijayasree, N K; Chaitanya, P Abstract: Complexity of mufflers generally introduces considerable pressure drop, which affects the engine performance adversely. Not much literature is available for pressure drop across perforates. In this paper, the stagnation pressure drop across perforated muffler elements has been measured experimentally and generalized expressions have been developed for the pressure loss across cross-flow expansion and cross-flow contraction elements. A flow resistance model available in the literature has been made use of to analytically determine the flow distribution and thereby the pressure drop of mufflers. A generalized expression has been derived here for evaluation of the equivalent flow resistance for parallel flow paths. Expressions for flow resistance across perforated elements, derived by means of flow experiments, have been implemented in the flow resistance network. The results have been validated with experimental data. Thus, the newly developed integrated flow resistance networks would enable us to determine the normalized stagnation pressure drop of commercial automotive mufflers, thus enabling an efficient flow-acoustic design of silencing systems. Page(s): 339-349

Hydrothermal ageing effects on flexural properties of GFRP composite laminates

2013-11-08T16:33:40Z

Title: Hydrothermal ageing effects on flexural properties of GFRP composite laminates Authors: Rao, P Sampath; Hussain, M Manzoor Abstract: The usage and replacement of conventional materials with polymer composite materials for engineering applications is always questioned by the end user, unless otherwise the research oriented reliable supporting certification is made available. The reinforcement materials are highly hygroscopic; the matrix material provides protection to the reinforcement. Since the composite component’s edges are exposed to environment, water molecules travel along the reinforcement, that may cause damage to the interfacial bonding, further the performance of the composite laminate may get affected. This study of resistance of glass fiber reinforced polymer composite (GFRP) subjected to hydrothermal ageing and their flexural behavior under different temperature and exposure time. GFRP samples were prepared by using resin transfer molding (RTM) process and samples were exposed to different environmental conditions. Three point bending test is conducted and the test results indicate reduction in flexural modulus due to the degradation of GFRP under the environmental hydrothermal ageing conditions at 45°C strength decreases 23% to 70% and at 60°Cand 75°C strength decreases 50% to 77% over exposure period of 60 days. The results show that strength degradation by moisture absorption and temperature effect over the lifecycle impacts of GFRP composite exposed to water and temperature for long period of time. The performances of test results have been predicted by mathematical modeling. Page(s): 415-424

Solidification of heavy metal sludge using cement, fly ash and silica fume

2013-11-09T16:33:58Z

Title: Solidification of heavy metal sludge using cement, fly ash and silica fume Authors: Chindaprasirt, Prinya; Sinsiri, Theerawat; Napia, Chuwit; Jaturapitakkul, Chai Abstract: In this paper, the properties of solidified waste using ordinary Portland cement (OPC) containing silica fume (SF) and fly ash (FA) as a binder are reported. Silica fume and fly ash are used to partially replace ordinary Portland cement by 10% and 30% by weight, respectively. Plating sludge is used of 40, 50 and 60% by weight of the binder. A water to binder (w/b) ratio of 0.40 is used for all of the mixtures. The compressive strength of the solidified wastes is investigated. The leachability of heavy metals is determined by TCLP and XRD, and XRF is used to study the chemical properties, while the fractured surfaces are studied by SEM, and the pore size distribution is studied by MIP. The test results show that the setting time of the blended cement increased as the amount of plating sludge in the mix increased. In addition, the compressive strength of the blended cement increased with increasing curing duration time but at a decreasing rate. The compressive strengths at 28 days of the SF solidified waste mixes are 12.4, 2.7, 1.34 MPa and those of FA solidified waste mixes are 1.1, 1.0, 0.5 MPa at the plating sludge of 40, 50 and 60% by weight of the binder, respectively. The quality of the solidified waste containing SF and FA is better than that with OPC alone in terms of the effectiveness in reducing the leachability. The concentrations of heavy metals in the leachates are within the limits specified by the US EPA. Page(s): 405-414

DC conductivity studies of doped polyaniline tungsten oxide nanocomposites

2013-11-08T16:34:04Z

Title: DC conductivity studies of doped polyaniline tungsten oxide nanocomposites Authors: Sastry, D Nagesa; Revanasiddappa, M; Basavaraja, C; Suresh, T; Raghavendra, S C Abstract: Camphor sulfonic acid (CSA) doped polyaniline (PANI) and tungsten oxide (WO₃) composites (PANI/CSA/WO₃) have been prepared by in situ deposition technique by placing different wt% of fine grade nano powder of WO₃(PANI/CSA/WO₃ -10, -20, -30, -40 and -50%) during polymerization of polyaniline. The polymerization of aniline is carried by using ammonium peroxydisulfate as oxidizing agent. The composites are characterized by various physical methods such as Fourier transform infrared spectra (FTIR), X-ray diffractogram (XRD), thermo-gravimetric analysis (TGA), scanning electron micrograph (SEM) and transmission electron micrographs (TEM). The FTIR spectral data shows the homogeneous distribution of WO₃ nano particles in PANI/CSA polymer matrix. The TGA reveals that PANI interacted strongly with the WO₃-SO₃H, enhancing the thermal stability of polyaniline. The SEM images indicate that increase of WO₃ wt% in PANI/CSA/WO₃ composites, enhances the compactness of the matrix. The TEM image clearly shows the size distribution of WO₃ nanoparticles formed during the reaction and ranges from 150 to 200 nm. The temperature dependent DC conductivity of PANI/CSA/WO₃ composites is studied in the temperature range 308-433 K. The results of PANI/CSA/WO₃ indicate strong interaction of PANI/CSA with WO₃ in the composites. The study of DC conductivity shows an evidence for the transport properties of the composites. Due to the positive temperature coefficient of resistance of WO₃, these composites can signify in development of new materials in temperature dependent applications. Page(s): 435-442