Anetor L.,Nigerian Defence Academy
Australian Journal of Mechanical Engineering | Year: 2013
A combined study based on laser Doppler velocimetry measurements and numerical simulation was undertaken in order to validate the KIVA II numerical code. A rapid intake and compression machine was used for the experimental studies, while the numerical calculations were performed with the KIVA II computational fluid dynamics code. The k-∈ turbulence model was used to represent the effects of turbulence. The measured mean radial and tangential velocities were found to be generally higher than their computed counterparts. The differences between these velocities range from 3.5% to 7% in magnitude for the re-entrant bowl chamber while they vary from 5% to 11% for the bowl-in-piston combustion chamber configuration. The measured values of the turbulence intensity close to the bowl axis in the re-entrant bowl chamber configuration were fairly accurately predicted, but the quality of the prediction diminishes as the bowl entrance region was approached. The values of the turbulence intensity were however, poorly reproduced near the axis of the bowl-in-piston chamber assembly. The experimental and predicted values of turbulence were found to differ by between 7% to 20% (re-entrant chamber) and 13% to 20% (bowl-in-piston). The results of the experimental data that were obtained from this study show that the random uncertainties in the mean radial and tangential velocities for both chamber configurations range from ±13.2% to ±19.2%, while the uncertainties in the root mean square velocities were about ±14.1%. © Institution of Engineers Australia, 2013.
Ademoh N.A.,Nigerian Defence Academy
International Journal of Physical Sciences | Year: 2010
Defined quantities of the vegetable oil extracted from the seed of neem tree were mixed with each of four commercial grades of Nigerian gum arabic exudates as hybrid binders for foundry sand cores. The cores which were made with silica sand were classified and oven baked at 200°C for 1 - 3 h, oven cooled and then tested for tensile strength using standard universal strength machine to ascertain their level of suitability for industrial casting. The specimens for tensile strength were shaped like figure eight. The result showed that grade 2 gum arabic hybrids with Neem oil offered best economic advantage as it attained required tensile strength after the shortest period of baking. It was followed by the grade 4, grade 1 and then grade 3 gum arabic based hybrids with neem oil in that order. The benefit of hybridizing Nigerian gum arabic exudates with neem oil was more pronounced when cores were baked at about the melting temperature of the grade of gum arabic involved. Baking cores below the melting point marginally improved bond strength while baking them at temperatures well above melting point depressed tensile strength. © 2010 Academic Journals.
Igwilo I.O.,Nnamdi Azikiwe University |
Ogoke T.J.,Nnamdi Azikiwe University |
Ogbu D.O.,Nnamdi Azikiwe University |
Igwilo S.N.,University of Nigeria |
And 2 more authors.
Pakistan Journal of Biological Sciences | Year: 2013
Moringa oleifera is a multipurpose tree, cultivated in the tropics and sub-tropics for its nutritional and therapeutic properties. The raw matured seeds which have been reported to be used as food and clarifying agent of turbid water caused growth retardation in albino rats and this might have been due to its anti-nutritional contents. Owing to these adverse factors, the effect of soaking the seeds for 30 min and then compounding it as feeds was done. Its effect on growth rate and the level of some biochemical parameters on rats were investigated. The Wistar albino rats were fed for 21 days and their weights measured at 2 days interval. Aspartate and Alanine transaminases, Alkaline phosphatase and total bilirubin levels were assayed using Automated Vitros 350 Chemistry Analyzer. The growth rates of rats fed with the commercial rat pellets, Casilan diet and the processed Moringa seed diet had a range of 80.06±3.54 to 100.98±5.37, 66.70±7.54 to 55.23±7.47 and 52.99±4.15 to 35.47±2.26, respectively. The parameters assayed for the group that received the processed Moringa seed diet are 144.00±16.80 (AST), 41.00±7.05 (ALT), 66.50±8.80 (ALP) and 12.45±1.18 (Total Bilirubin). The one-way ANOVA statistical analysis indicated that there was no significant change in the parameters of all the groups at 95% significance level (p<0.05). Hence, the soaked Moringa oleifera seed did not support growth in the animal subjects and also did not pose a threat to the liver. However, it is better to develop more suitable processing methods to improve the seed's nutritional capabilities. © 2013 Asian Network for Scientific Infomation.
Anetor L.,Nigerian Defence Academy |
Osakue E.,Texas Southern University |
Odetunde C.,Texas Southern University
Engineering Journal | Year: 2012
In combustion computational analysis, reduced mechanisms are often used in place of detailed kinetic chemistry. Since the computational costs of including all the species in the reactor model are always prohibitively high, several reduced mechanisms have been developed for propane and other hydrocarbon oxidation. In this study we employed ANSYS Fluent Computational Fluid Dynamics (CFD) package, (hereinafter referred to as Fluent) to analyze propane oxidation mechanism in a conical reactor. The k -scheme was used to model the effects of turbulence. The reaction kinetics employed in this study is that based on the work of Westbrook and Dryer . This simplified model consists of 5 chemical reactions and 12 species, namely, C 3H 8, CO 2, CO, H2O, NO, O 2, O, H, N, OH, N 2 and H 2. The computed mass fractions of the species, C 3H 8, CO 2, CO and H2O were found to be in agreement measured values presented in . The results show that the bulk of the turbulent kinetic energy was produced in the inlet jet. The computed values of were found to confirm that the use of the law-of-the-wall functions was valid and also showed that the computational mesh for the present model was appropriate.
Jonah S.A.,Ahmadu Bello University |
Ibrahim Y.V.,Ahmadu Bello University |
Ajuji A.S.,Ahmadu Bello University |
Onimisi M.Y.,Nigerian Defence Academy
Annals of Nuclear Energy | Year: 2012
Miniature Neutron Source Reactor (MNSR) facilities are equipped with 10 irradiation channels mainly for NAA and limited radioisotope production. A neutronics feasibility study has shown that it would be feasible to convert commercial MNSR from HEU (90.2%) to LEU (∼12.5%) fuel. In this work, the impact of the proposed LEU fuel on neutron spectrum parameters in the irradiation channels has been studied. The MCNP code was used to calculate the neutron flux distribution in 640 neutron energy group structure and the cross section data of monitor reactions also in 640 neutron energy group structure were extracted from ENDF libraries. On the basis of the data, the Cd ratios for Au, Co, Th, and U were computed and used to estimate the thermal-to-epithermal neutron ratio, f, as well as the non-ideality of epithermal neutron spectrum, α. In order to verify the calculations, measured experimental data for the current HEU core are compared with calculations. Results obtained indicate slightly "hardened" neutron spectra distributions in the inner and outer irradiation channels of the proposed LEU core with no significant impact on utilization. © 2011 Elsevier Ltd. All rights reserved.