An adaptive projection method for the modeling of unsteady, low-Mach number combustion

In this paper the authors present an adaptive projection method for modeling unsteady, low-Mach reacting flow in an unconfined region. The equations they solve are based on a model for low-Mach number combustion that consists of the evolution equations for density, species concentrations, enthalpy, and momentum coupled with a constraint on the divergence of the flow. The algorithm is based on a projection methodology in which they first advance the evolution equations and then solve an elliptic equation to enforce the divergence constraint. The adaptive mesh refinement (AMR) scheme uses a time-varying, hierarchical grid structure composed of uniform rectangular grids of varying resolution. The integration scheme on the grid hierarchy is a recursive procedure in which a coarse grid is advanced, fine grids are advanced multiple steps to reach the same time as the coarse grid, and the coarse and the fine grids are synchronized. The method is valid for multiple grids on each level and multiple levels of refinement. The method is currently implemented for laminar, axisymmetric flames with a reduced kinetics mechanism and a Lewis number of unity. Two methane-air flames, one steady and the other flickering, are presented as numerical examples

Toksikokinetika prometrina u mozgu miševa

Prometryne is a methylthio-s-triazine herbicide. Signifi cant trace amounts are found in the environment, mainly in water, soil, and food plants. The aim of this study was to establish brain and blood prometryne levels after single oral dose (1 g kg-1) in adult male and female mice. Prometryne was measured using the GC/MS assay at 1, 2, 4, 8, and 24 h after prometryne administration. Peak brain and blood prometryne values were observed 1 h after administration and they decreased in a time-dependent manner. Male mice had consistently higher brain and blood prometryne levels than female mice. The observed prometryne kinetics was similar to that reported for the structurally related herbicide atrazine.Prometrin je metiltio-s-triazinski herbicid. Značajne količine prometrina zaostaju u tragovima u okolišu, poglavito u vodi, tlu i biljkama koje rabimo za prehranu. Cilj je rada izmjeriti količinu prometrina koja se apsorbira u mozgu i krvi nakon primijenjene akutne oralne doze (1 g kg-1 tjelesne mase) u odraslih miševa obaju spolova. Razine prometrina u mozgu i krvi izmjerene su GC/MS-om tijekom 1., 2., 4., 8. i 24. sata nakon izlaganja. Utvrđeno je da je udio prometrina koji se zadržava u živčanom tkivu relativno nizak ali detektabilan u odnosu na koncentraciju u krvi i koncentraciju primijenjene doze. Najviše koncentracije u krvi i maseni udjeli u mozgu zabilježeni su tijekom 1. sata nakon izlaganja, a s vremenom izmjerene vrijednosti značajno opadaju. Uočena je značajna razlika između mužjaka i ženki pri čemu mužjaci imaju značajno više razine prometrina u mozgu i krvi nego ženke. Opisana toksikokinetika prometrina pokazuje sličnosti s otprije opisanom i poznatom toksikokinetikom strukturalno sličnog herbicida atrazina

Como a Numerical Model for Predicting Furnace Performance in Axisymmetric Geometries

A computer code is being developed to model steady-state, swirling, natural gas or pulverized coal combustion. This computer program is based on fundamental physics and chemistry and is uniquely organized into independent modules that model the various interacting processes which occur during combustion: flow, heterogeneous and homogeneous chemical reaction, and heat transfer. As models are improved or as new ones are developed, this modular structure allows portions of the program to be updated with minimal impact on the remainder of the program. These models will eventually assist combustion designers in the understanding of the complex combustion processes. In this paper, swirling methane combustion and nonswirling pulverized coal combustion are investigated. Numerical results for flow, heat transfer, and chemistry are presented for each case and compared with available data and predictions. These initial studies have been useful in providing additional insight into the understanding of these complex combustion processes

Furmo A Numerical Model for Predicting Performance of Three-Dimensional Pulverized-Fuel Fired Furnaces

A numerical furnace model (FURMO) was developed to model steady-state, three-dimensional pulverized-fuel combustion in practical furnace geometries. This model is based on a fundamental description of various interacting processes which occur during combustion: turbulent flow, heterogeneous and homogeneous chemical reaction and heat transfer. The detailed analysis achieved by the method is useful for evaluating furnace performance and in the interpretation of laboratory, intermediate and utility test data. In this paper, three-dimensional pulverized coal combustion is investigated for a 560 MW Utility Boiler. Numerical results for flow, heat transfer and chemistry are presented. Contour maps are exhibited to describe these complex three-dimensional interactions