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251	Numerical study of hot jet ignition of hydrocarbon-air mixtures in a constant-volume combustor Karimi, Abdullah January 2014 (has links) Indiana University-Purdue University Indianapolis (IUPUI) / Ignition of a combustible mixture by a transient jet of hot reactive gas is important for safety of mines, pre-chamber ignition in IC engines, detonation initiation, and in novel constant-volume combustors. The present work is a numerical study of the hot-jet ignition process in a long constant-volume combustor (CVC) that represents a wave-rotor channel. The mixing of hot jet with cold mixture in the main chamber is first studied using non-reacting simulations. The stationary and traversing hot jets of combustion products from a pre-chamber is injected through a converging nozzle into the main CVC chamber containing a premixed fuel-air mixture. Combustion in a two-dimensional analogue of the CVC chamber is modeled using global reaction mechanisms, skeletal mechanisms, and detailed reaction mechanisms for four hydrocarbon fuels: methane, propane, ethylene, and hydrogen. The jet and ignition behavior are compared with high-speed video images from a prior experiment. Hybrid turbulent-kinetic schemes using some skeletal reaction mechanisms and detailed mechanisms are good predictors of the experimental data. Shock-flame interaction is seen to significantly increase the overall reaction rate due to baroclinic vorticity generation, flame area increase, stirring of non-uniform density regions, the resulting mixing, and shock compression. The less easily ignitable methane mixture is found to show higher ignition delay time compared to slower initial reaction and greater dependence on shock interaction than propane and ethylene. The confined jet is observed to behave initially as a wall jet and later as a wall-impinging jet. The jet evolution, vortex structure and mixing behavior are significantly different for traversing jets, stationary centered jets, and near-wall jets. Production of unstable intermediate species like C2H4 and CH3 appears to depend significantly on the initial jet location while relatively stable species like OH are less sensitive. Inclusion of minor radical species in the hot-jet is observed to reduce the ignition delay by 0.2 ms for methane mixture in the main chamber. Reaction pathways analysis shows that ignition delay and combustion progress process are entirely different for hybrid turbulent-kinetic scheme and kinetics-only scheme. Thermodynamics -- Research Turbulence -- Research -- Testing Reaction mechanisms (Chemistry) Heat -- Transmission Rotors -- Combustion -- Testing Chemical kinetics -- Research -- Testing Internal combustion engines -- Ignition Hydrocarbons -- Research Methane -- Thermal properties Ethylene -- Thermal properties Propane -- Thermal properties Hydrogen -- Thermal properties Jets -- Ignition Shock waves Chemical reactors Materials at high pressures Numerical analysis -- Methodology Air -- Thermal properties
252	Licence to Talk : Sustainability Managers and their Managerial Realities within the Corporate Sustainability Paradox El hajjari Borg, Mounia, Sundberg, Elin January 2021 (has links) While sustainability-dedicated managers and related titles represent a profession that has hardly existed for more than a decade, it is not surprising that the field of research concentrating on these professionals is in itself relatively new. With an increasing demand for corporations to take their social and environmental responsibility, and a corporate sustainability characterized by tension and paradox, we found it of importance to explore the role and entanglements of these professionals. By analysing 17 in-depth interviews with sustainability-dedicated professionals from the private sector in Sweden, our interpretation is that sustainability managers hold the function of selling sustainability, with talk as their main weapon. Expressly, in the intersection between business-case logics and sustainability logics, sustainability managers have to, above all, make a convincing case for sustainability, inwards and outwards. Therefore, they draw dynamically on different narratives which we conceptualise in three roles: the chameleon, the pragmatic, and the nagging manager. Through these roles, we intend to capture the fluidity with which the managers relate and engage with sustainability, and hence we do not mean to ossify a role’s dynamics within a single, static or stereotypical category. We discuss these findings and concepts to the background of previous studies and existing literature. Sustainability managers sustainability-dedicated professionals sustainable development sustainable management corporate sustainability corporate paradox CSR stakeholders governance sustainability strategies communication strategic communication sustainability reporting non-financial disclosure private sector in Sweden paradox approach paradox perspective business case social and environmental responsibility organizations multinationals MNC Nils Brunsson organizational theory organizational hypocrisy neo-institutionalism organizational individuals decision-making action business operations isomorphism institutional logics market logics reporting frameworks GRI global reporting initiative walk the talk change making change agent systemic change behaviour and human resources identity work organizational sociology legitimacy Hållbarhetschefer hållbarhetsrelaterade roller hållbar utveckling hållbar ledning hållbarhet paradox CSR intressenter styrning hållbarhetsstrategier kommunikation strategisk kommunikation hållbarhetsrapportering icke-finansiell information privat sektor i Sverige paradox perspektiv affärsstrategi socialt och miljöansvar organisationer multinationella företag MNC Nils Brunsson organisationsteori organizational hypocrisy hyckleri neo-institutionalism organisatoriska individer individnivå beslutsfattande affärsverksamhet isomorfism institutionell logik marknadslogik rapporteringsramverk GRI global reporting initiativ walk the talk förändringsarbete förändringsagent systemförändring beteende och mänskliga resurser identitetsarbete organisatorisk sociologi legitimitet externa och interna påtryckningar. Social Sciences Samhällsvetenskap

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Numerical study of hot jet ignition of hydrocarbon-air mixtures in a constant-volume combustor

Licence to Talk : Sustainability Managers and their Managerial Realities within the Corporate Sustainability Paradox