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Visar resultat 1 - 5 av 28 avhandlingar som matchar ovanstående sökkriterier.

1. 1. A Realizable Hybrid Mixture-Bubble Model for Cavitating Flows

   Författare :Ebrahim Ghahramani; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Multi-scale model; Homogeneous mixture model; Cavitation; Disperse multiphase flow; Eulerian-Lagrangian model; OpenFOAM;

   Sammanfattning : Cavitating multi-phase flows include an extensive range of cavity structures with different length scales, from micro bubbles to large sheet cavities that may fully cover the surface of a device. To avoid high computational expenses, incompressible transport equation models are considered a practical option for simulation of large scale cavitating flows, normally with limited representation of the small scale vapour structures. LÄS MER

3. 2. Numerical simulation and analysis of multi-scale cavitating flows using a hybrid mixture-bubble model

   Författare :Ebrahim Ghahramani; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Homogeneous mixture model; Lagrangian bubble model; CFD; Cavitation; OpenFOAM; Multiphase flow; Hybrid model; Multi-scale;

   Sammanfattning : The aim of this research is to model and analyse multi-scale cavitating flows with a certain emphasis on small sub-grid vapour structures. Cavitating flows include vapour structures with different length scales, from micro-bubbles to large cavities. LÄS MER

4. 3. Model-Based Control of Gasoline Partially Premixed Combustion

   Författare :Gabriel Ingesson; Institutionen för reglerteknik; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Pressure-Sensor Feedback; Model Predictive Control; Model-Based Controller Design; Partially Premixed Combustion;

   Sammanfattning : Partially Premixed Combustion (PPC) is an internal combustion engine concept that aims to yield low NOx and soot emission levels together with high engine efficiency. PPC belongs to the class of low temperature combustion concepts where the ignition delay is prolonged in order to promote the air-fuel-mixture homogeneity in the combustion chamber at the start of combustion. LÄS MER

5. 4. The Effective Convectivity Model for Simulation and Analysis of Melt Pool Heat Transfer in a Light Water Reactor Pressure Vessel Lower Head

   Författare :Chi Thanh Tran; Tomas Lefvert; Harri Tuomisto; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; light water reactor; hypothetical severe accident; accident progression; accident scenario; core melt pool; heat transfer; turbulent natural convection; heat transfer coefficient; phase change; mushy zone; crust; lower plenum; analytical model; effective convectivity model; CFD simulation; Thermal energy engineering; Termisk energiteknik;

   Sammanfattning : Severe accidents in a Light Water Reactor (LWR) have been a subject of intense research for the last three decades. The research in this area aims to reach understanding of the inherent physical phenomena and reduce the uncertainties in their quantification, with the ultimate goal of developing models that can be applied to safety analysis of nuclear reactors, and to evaluation of the proposed accident management schemes for mitigating the consequences of severe accidents. LÄS MER

7. 5. Homogeneous Ignition - Chemical Kinetic Studies for IC-Engine Applications

   Författare :Per Amnéus; Förbränningsfysik; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Skeletal mechanism; Mechanism reduction; n-heptane; iso-octane; formaldehyde; methane; Motors and propulsion systems; Motorer; framdrivningssystem; Physics; Fysik; Detailed chemistry; Kinetic calculations; Engine knock; Homogeneous charge compression ignition; HCCI; Fysicumarkivet A:2002:Amnéus;

   Sammanfattning : Calculations on a Homogeneous Charge Compression Ignition (HCCI) engine have been performed. Zero-dimensional models were used. The simplest model compressed the gas to auto-ignition, using temperature and pressure at a certain crank angle position obtained from engine experiments. LÄS MER