http://nopr.niscair.res.in/handle/123456789/7205 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/7626 Title: A combined CFD and network approach for a simulated turbine blade cooling system <br/> <br/>Authors: Kumar, B V N Rama; Prasad, B V S S S <br/> <br/>Abstract: A combined computational fluid dynamics (CFD) and network analysis is proposed as an approach to solve complex flow and heat transfer problems. Perforated cylindrical passages with impingement and film cooling arrangement in a circular cylinder are considered as an example for demonstrating the methodology and simulated a cooled turbine blade geometry. Two networks namely, flow and thermal networks are developed. CFD calculations are performed to estimate loss factors and thermal resistances, which are used as input to the flow and thermal networks. Iterative procedures are adopted for solving the networks. Results of the pressure and temperature at different nodes, flow rates through the elements and film hole effectiveness in the span-wise and peripheral directions are presented at selected positions for different pressure inlet conditions of coolant. The results indicate that 0.15% increase in coolant to mainstream flow ratio causes 20% reduction in coolant outlet temperature and 25% increment in film cooling effectiveness. <br/> <br/>Page(s): 195-201 Mon, 29 May 2006 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/7557 Title: Predicting adiabatic exponent as one of the important factors in evaluating detonation performance <br/> <br/>Authors: Keshavarz, M H; Pouretedal, H R <br/> <br/>Abstract: A new correlation is given to estimate the Chapman-Jouguet adiabatic (gamma) exponent, <img src='/image/spc_char/gamma.gif' border=0>_CJ, as a criterion for choice among conflicting detonation pressure measurements at any loading densities, greater as well as less than 1 g/cc. The <img src='/image/spc_char/gamma.gif' border=0>_CJ value obtained by new correlation is relatively insensitive to elemental composition and is primarily a function of loading density. Calculated g_CJ by this procedure shows good agreement with respect to corresponding measured values as compared to complicated computer code BKW-EOS as well as reported empirical methods. <br/> <br/>Page(s): 259-263 Mon, 29 May 2006 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/7556 Title: Studies on poly(vinyl chloride)/fatty acid blends as shape-stabilized phase change material for latent heat thermal energy storage <br/> <br/>Authors: Sarı, Ahmet; Kaygusuz, Kamil <br/> <br/>Abstract: The present study aims to prepare novel shape-stabilized phase change materials (PCMs) by using fatty acids [(lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA)] as PCM and poly(vinyl chloride) (PVC) as supporting material, and to determine their thermal properties such as melting temperature and the latent heat storage capacity. The maximum composition ratio of all fatty acids in the shape-stabilized PCMs has been found as 50 wt% in which no leakage of fatty acid is observed over their melting temperatures for several heating cycles. The miscibility of fatty acids with the PVC and the interaction between the blend components which is responsible for the miscibility has been proved by microscopic investigation and Infrared (IR) spectroscopy. The melting temperature and the latent heat of fusion of the shape-stabilized PCMs are measured by differential scanning calorimetry (DSC) analysis method. The melting temperatures and latent heats of the shape-stabilized PVC/LA, PVC/MA, PVC/PA and PVC/SA (50/50 wt%) PCMs are determined as 38.8, 49.2, 54.4 and 64.7^oC and 97.8, 103.2, 120.3 and 129.3 J/g, respectively. The results indicate that the PVC/fatty acids blends as shape-stabilized PCMs have great potential for passive solar thermal energy applications in terms of their satisfactory thermal properties and advantages of easy preparation with desirable dimensions and direct utility in LHTES applications. <br/> <br/>Page(s): 253-258 Mon, 29 May 2006 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/7555 Title: Effects of expanded perlite aggregate and different curing conditions on the drying shrinkage of self-compacting concrete <br/> <br/>Authors: Türkmen, İbrahim; Kantarci, Abdulhamit <br/> <br/>Abstract: Fresh self-compacting concrete (SCC) flows into place and around obstructions under its own weight to fill the formwork completely and self-compact, without any segregation. The present study investigates drying shrinkage of SCC including mixtures of expanded perlite (EPA) and natural aggregates (NA) at six different curing conditions. The binder dosage is kept constant at 450 kg/m³ throughout the study. A superplasticizer is used as 2% (by weight) of Portland cement (PC) to reduce water/cement+mineral (w/cm) ratios and self-compacting. Specimens have been exposed to conditions of lime-saturated water (B1), dry in air (B2), coated with paraffin (B3), three times wetted in a day (B4), under wet-sack (B5) and 100% relative humidity (B6). It has been found that drying shrinkage of concrete is reduced by using EPA. The drying shrinkage of EPA concrete decreases with an increasing moisture content. It is also found that concrete exhibits a lower drying shrinkage in all time periods under the B1 curing conditions. <br/> <br/>Page(s): 247-252 Mon, 29 May 2006 22:58:59 GMT