Library

2308 match your search

This paper compares two mean reaction rate closures for turbulent reacting flow: the Stochastic Fields (SF) method and the Direct Quadrature Method of Moments using the Interaction by Exchange with the Mean micromixing model (DQMoM-IEM). The methods have many common features and have received significant attention in recent literature, yet have not been systematically compared. We present both methods in the same mathematical framework and compare their numerical performance. In addition, we introduce antithetic sampling as a variance reduction technique to increase the efficiency of the SF...
A comparative study of predictions obtainable using the conformal and indirect interfaces for Conjugate Heat Transfer (CHT) analysis in an exhaust manifold was undertaken with a view to ascertain the degree of closeness of certain pre-defined physical quantities. The Indirect Mapped Interface feature has been incorporated in the latest release version (V7.02) of the multidisciplinary engineering simulation tool STAR-CCM+ and enables the use of non-conformal mesh at the interface between solid and fluid domains for CHT simulations. A steady-state analysis was performed for base mesh size...
A comparative study of predictions obtainable using the conformal and indirect interfaces for Conjugate Heat Transfer (CHT) analysis in an exhaust manifold was undertaken with a view to ascertain the degree of closeness of certain pre-defined physical quantities. The Indirect Mapped Interface feature has been incorporated in the latest release version (V7.02) of the multidisciplinary engineering simulation tool STAR-CCM+ and enables the use of non-conformal mesh at the interface between solid and fluid domains for CHT simulations. A steady-state analysis was performed for base mesh size...
This study examines the accuracy of solving the multi-component equations for a Proton Exchange Membrane Fuel Cell (PEMFC) by using a Computational Fluid Dynamics (CFD) technique. This technique uses an approximated multi-component (AMC) model with a correction term that guarantees the overall mass balance. Accuracy is assessed by comparing the species concentration computed with the Maxwell–Stefan and the corrected AMC models. This comparison is important because the structure of some CFD programs does not permit the direct use of the Maxwell–Stefan equations and this leads to confusion in...
Stringent emissions standards (Euro 6 and Tier2Bin5) lead to the use of nitrogen oxides (NOx) after treatment. One of the most widespread technical solutions able to meet these legislations is Urea Selective Catalytic Reduction (Urea SCR). A urea aqueous solution is introduced into the exhaust system in order to reduce NOx over SCR catalyst. Before reaching the catalyst, the aqueous solution has to be transformed into ammonia. Current serial applications need long distances (>400 mm) from injection point to SCR catalyst and a mixer apparatus to ensure sufficient mixing between exhaust gas...
The combustion chemistry of the two butane isomers represents a subset in a comprehensive description of C1–C4 hydrocarbon and oxygenated fuels. A critical examination of combustion models and their capability to predict emissions from this class of fuels must rely on high-quality experimental data that address the respective chemical decomposition and oxidation pathways, including quantitative intermediate species mole fractions. Premixed flat low-pressure (40 mbar) flames of the two butane isomers were thus studied under identical, fuel-rich ( ϕ =1.71) conditions. Two independent molecular-...
In its global development process GM-Powertrain follows a consequent “Road to Lab to Math” strategy, substituting road and laboratory tests with virtual tests. Hence simulation increasingly becomes a central aspect in the vehicle development process. With increasing accuracy of the single tools and a smart combination of different tools the credibility of the whole simulation chain comes closer to testing results. Furthermore the simulation gives us the possibility to change early and easily the product attributes in regard to functionality, robustness, comfort etc.. The enormous product cost...
In-cylinder air flow structures are known to play a major role in mixture preparation and engine operating limits for DISI engines. In this paper PIV was undertaken on in-cylinder flow fields for three different planes of measurement in the intake and compression strokes of a DISI engine for a low-load engine operating condition at 1500 RPM, 0.5 bar inlet plenum pressure (World Wide Mapping Point). One of these planes was vertical, cutting through the centrally located spark plug (tumble plane); the other two planes were horizontal, one close to TDC (10 mm below fire face) and the other one...
Lifeboats are important for the safety of crew on oil platforms and marine vessels. Their design has so far been mostly based on experimental studies. However, the large number of factors which influence the loads on the lifeboat structure and its occupants makes optimization studies by experimental means both time-consuming and expensive. Besides, many effects cannot be studied at laboratory scale due to the inability to match all similarity parameters, and certain conditions cannot be realized in a laboratory. Numerical simulations based on modern computational fluid dynamics (CFD) methods...
Trawlers account for the largest percentage of fishing vessels in Galicia. This kind of ships needs to provide high thrust at low advance ratios (it's usual operating velocities are around 3.5kn when the ship is towing the fishing net);because of this fact generally their propulsion units consist on ducted propellers. This paper summarizes some of the CFD calculations performed as starting point for trawler ducted propeller studies and highlights the capabilities of CFD as a valuable tool for the prediction of propulsive factors for ducted propellers. The calculations have been performed for...

Pages