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Biomass to energy conversion is particularly attractive on the microscale were internal combustion engines such as microturbines may be utilized coupled to an indirect gasification system. The authors have developed the IPRP technology based on rotary kiln pyrolisys and a pilot plant was built in Italy powered by an 80 kWEl microturbine fired by pyrolysis biomass syngas. This paper describes CFD numerical investigations carried out to study the combustion process occurring inside the annular rich-quick-lean combustion chamber of the given microturbine. A RANS analysis has been performed in...
Two rectangular cavity configurations at Mach 0.85 are investigated with the objective of assessing the extent to which 3D CFD with advanced turbulence modeling is capable of predicting narrowband and broadband flow noise. A non-linear, two-equation, eddy-viscosity model run in unsteady mode (URANS) is compared with Detached Eddy Simulation (DES) on a cavity with a L/D ratio of 5, representing cavity flow in so-called shear layer mode. Detailed experimental data for this cavity, configured with and without doors, provides a valuable opportunity to compare predictions of the spectra at many...
The paper presents the results of preliminary investigation of the effectiveness of using the vortex generators for improving the wake flow of large merchant ships. The idea of vortex generators is based on that from aerospace industry, where the vortex generators are used to prevent the flow separation on the suction side of the airplane’s wing – the vortices introduced to the boundary layer are attaching to the wing surface. It is expected that it is also possible to take advantage of this effect in ship design, by reducing the boundary layer thickness and reducing the areas of separated...
Mixing and separation of materials in multiphase flows are extremely common and frequent operations in chemical and process engineering. For example, stirred reactor is used to give good mixing and uniform dispersion of catalyst particles in the reactor to ensure uniform quality product is produced. At the end of the process, the catalyst particles may need to be recovered and removed from the product by separation equipment such as a settling tank. The commonly asked questions by plant operators in relation to these processes are: (a) What is the optimum rotating speed should be set for the...
In this thesis a numerical model for predicting areas with high risk of corrosion in biomass fired boilers has been developed. The model was developed through a literature study and tested in a full scale CFD analysis of the second boiler at Verdo heat and power plant. STAR-CCM+ was used for the CFD calculations. The model is based on the metal temperature of heat transfer surfaces in the boiler and the concentrations of potassium chloride(KCl) and oxygen(O2). A series of preliminary analyses of the used models were conducted in order to validate the simulation of the combustion processes...
This project is one component of a broader effort whose ultimate goal is to provide CFD-based tools that can be used to optimize the design of urea SCR NOx aftertreatment systems for heavy-duty diesel engines. Here the focus is on predicting the distributions of key chemical species (ammonia, in particular) at the inlet to the catalysts. Two aspects of the physical models have been emphasized: the multi-phase models, and the gas-phase chemistry models. A hierarchy of four simplified geometric configurations has been used for model development and parametric studies, and to establish the...
In this study, we use CFD simulations to model a fully nonlinear water wave tank. Firstly, for validation purpose, regular waveswith different wave steepness are simulated and the results are compared with the second-order potential flow solution for the free surface displacement time history at fixed locations, the instantaneous free surface spatial profiles, and the velocity and pressure fields under the free surface. It is shown that for small wavesteepness, the CFD solutions agree very well with the second-orderpotential flow solutions while for large wave steepness, apparent differences...
Three-dimensional computational fluid dynamics (CFD) method was used to model the boiling two-phase flow in one of the PSBT 5-by-5 rod bundle tests. The rod bundle with all the spacers was modeled explicitly using unstructured computational grids. The “six-equation, two-fluid model” with the wall boiling model were used to model the boiling two-phase flows in the bundle. The computed void fractions compare well with the measured data at the measuring plane. In addition to the averaged void data, the CFD results give a very detailed picture of the flow and void distributions in the bundle and...
Unsteady numerical simulations of air flow, mixed with micron particles, through a human lung conducting zone during inhalation have been performed. The process included importing images from a high resolution CT-Scan into a CFD software, generation of the CFD model and then CFD simulation over a 4 seconds cycle (2 seconds for inhalation and 2 seconds for exhalation). The inlet diameter was 11 mm and the flow rates were 5, 7.5, and 15 liters/ min. Only results for the highest flow rate are presented. The implicit-unsteady Reynolds Average Navier-Stokes equations with the Wilcox K-ω turbulence...

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