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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...
A numerical study of the heat transfer from an air-cooled single-cylinder engine has been undertaken using computational fluid dynamics. The variation in heat transfer from and airflow around the cylinder, which was simplified to a stack of annular fins, was observed at different values of fin pitch and length. The simulation results were compared with experimental results obtained previously at Queen's University Belfast (QUB). The CFD prediction of the circumferential temperature distributions had a similar trend to the experimental analysis, offset from the experimental results by...
The aim of this research is to investigate parameters that affect the behaviour of a damaged ship and also to assess the ability of RANS codes to accurately model the physical processes occurring in the flooding of a damaged ship. Initially, the flooding of a damaged ship has been divided into smaller components to assess the accuracy of the predictions for these flow-fields when validated against experiment or other simulation methods. These components are: 1. Violent floodwater motions 2. Modelling a seaway 3. Compartment flooding rates 4. Rigid body motions
Turbomachinery Heat Transfer Analysis and Simulation
As gas turbine operating temperatures increase, thermal management methods become critical. Designing turbine blades and vanes with sufficient cooling is necessary to avoid blade damage and performance degradation. Along with the importance of knowing bulk fluid and solid temperatures, it is also important to characterize complex flow features as well as temperature uniformity and hot-spots. Additionally, blade-row interaction such as wake impingement and thermal stacking must be considered. Multi-physics analysis methods can be used in the design phase to avoid thermal management problems...
Efficient Modeling of Complex Heat Sinks Series 2 Part 1
Heat sinks are the most common heat exchange devices in electronics systems whether the system as a whole utilizes a forced—or natural—convective cooling approach. The effectiveness of the heat sink greatly depends on the material used and the geometry that can be manufactured. In the past decade, manufacturing technology advances have permitted far more complex heat sinks to be cost-effectively made in high volumes. While the increased geometric complexity provides great benefits for the overall thermal system design, the new geometries provide additional challenges to anyone performing...

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