The measurement of droplet velocities in Diesel sprays close to the nozzle is important because of the complexity of in-nozzle flow, spray break-up and evaporation. However, the measurement of droplet velocities in th...The measurement of droplet velocities in Diesel sprays close to the nozzle is important because of the complexity of in-nozzle flow, spray break-up and evaporation. However, the measurement of droplet velocities in the dense region of Diesel sprays is very difficult or impossible by means of widely used laser diagnostic techniques, in particular under engine-like high-pressure and high-temperature conditions. The limitations of phase Doppler anemometry （PDA） and particle image velocimetry （PIV） prevent the application to the ultra-dense region of the spray. It was demonstrated that these problems can be greatly reduced by the laser flow tagging （LFT） technique. It was also demonstrated recently that LFT measurements can be conducted in clustered Diesel jets with improved spatial resolution and increased number of simultaneous measurements in the near-nozzle region. In the present work, the nozzle design, the temperature and pressure of the ambient air, and the fuel rail pressure are varied, in order to investigate the influence on the near-nozzle jet velocity and the underlying physical mechanisms.展开更多
Abstract： In the light of an increasing software complexity, many product variants and challenging market conditions, the automotive industry focuses two mitigation approaches： development processes and SW （softwar...Abstract： In the light of an increasing software complexity, many product variants and challenging market conditions, the automotive industry focuses two mitigation approaches： development processes and SW （software） architecture are standardized while model-driven software development technologies are progressively applied for series development. However, software architecture is subject to a continuous shift of requirements and boundary conditions. At the same time, process standards ensure necessary quality but also cause a dramatic increase of the SW development effort. There exists a methodical gap between process and market requirements on one hand and reusable standardized software functions with a high quality on the other. In this paper, an approach is presented that aims for the continuous extension of powertrain control software with increasing quality based on existing boundary conditions and a consequent methodical extension of existing technical concepts. We address this by the development of a sustainable software architecture which enables the safeguarding of consistent design principles and thus higher development efficiency. Moreover, it opens the door to a comprehensive quality assurance concept based on the agile software development principle Continuous Integration. Finally, the feasibility of this approach and software quality assessment results are shown by the application for a gasoline engine in the vehicle.展开更多
Modern diesel passenger cars already fulfill high demands regarding the reduction in NOx emissions through complex exhaust aftertreatment systems.With the consideration of real driving emissions,the reduction in NOx e...Modern diesel passenger cars already fulfill high demands regarding the reduction in NOx emissions through complex exhaust aftertreatment systems.With the consideration of real driving emissions,the reduction in NOx emissions in high transient engine operation becomes even more challenging.Apart from increasing the complexity of exhaust aftertreatment systems,internal engine measures play a major role.The approach to reducing NOx emissions described in this paper uses the precise control of the combustion.For this purpose,the method of digital combustion rate shaping control is applied,which allows the realization of a predefined combustion by automatically adapting the injection profile during operation.Within this work,this controller is extended in order to control the predefined combustion trace based on target NOx values.First,the working principal of the state-of-the-art digital combusting rate shaping controller is explained.In the next step,the design and strategy of the extended control approach are explained and validated.Finally,its potential to reduce engine-out NOx emissions during transient driving situations is evaluated based on simulations of the WLTC.It is shown that the control concept fulfills the requirements and is able to effectively reduce high NOx peaks during transient operation.展开更多
文摘The measurement of droplet velocities in Diesel sprays close to the nozzle is important because of the complexity of in-nozzle flow, spray break-up and evaporation. However, the measurement of droplet velocities in the dense region of Diesel sprays is very difficult or impossible by means of widely used laser diagnostic techniques, in particular under engine-like high-pressure and high-temperature conditions. The limitations of phase Doppler anemometry （PDA） and particle image velocimetry （PIV） prevent the application to the ultra-dense region of the spray. It was demonstrated that these problems can be greatly reduced by the laser flow tagging （LFT） technique. It was also demonstrated recently that LFT measurements can be conducted in clustered Diesel jets with improved spatial resolution and increased number of simultaneous measurements in the near-nozzle region. In the present work, the nozzle design, the temperature and pressure of the ambient air, and the fuel rail pressure are varied, in order to investigate the influence on the near-nozzle jet velocity and the underlying physical mechanisms.
文摘Abstract： In the light of an increasing software complexity, many product variants and challenging market conditions, the automotive industry focuses two mitigation approaches： development processes and SW （software） architecture are standardized while model-driven software development technologies are progressively applied for series development. However, software architecture is subject to a continuous shift of requirements and boundary conditions. At the same time, process standards ensure necessary quality but also cause a dramatic increase of the SW development effort. There exists a methodical gap between process and market requirements on one hand and reusable standardized software functions with a high quality on the other. In this paper, an approach is presented that aims for the continuous extension of powertrain control software with increasing quality based on existing boundary conditions and a consequent methodical extension of existing technical concepts. We address this by the development of a sustainable software architecture which enables the safeguarding of consistent design principles and thus higher development efficiency. Moreover, it opens the door to a comprehensive quality assurance concept based on the agile software development principle Continuous Integration. Finally, the feasibility of this approach and software quality assessment results are shown by the application for a gasoline engine in the vehicle.
基金This work is part of the Excellence Cluster“Tailor-made fuels from biomass,”which is funded by the Excellence Initiative of the Federal Government to promote science and research at German universities.
文摘Modern diesel passenger cars already fulfill high demands regarding the reduction in NOx emissions through complex exhaust aftertreatment systems.With the consideration of real driving emissions,the reduction in NOx emissions in high transient engine operation becomes even more challenging.Apart from increasing the complexity of exhaust aftertreatment systems,internal engine measures play a major role.The approach to reducing NOx emissions described in this paper uses the precise control of the combustion.For this purpose,the method of digital combustion rate shaping control is applied,which allows the realization of a predefined combustion by automatically adapting the injection profile during operation.Within this work,this controller is extended in order to control the predefined combustion trace based on target NOx values.First,the working principal of the state-of-the-art digital combusting rate shaping controller is explained.In the next step,the design and strategy of the extended control approach are explained and validated.Finally,its potential to reduce engine-out NOx emissions during transient driving situations is evaluated based on simulations of the WLTC.It is shown that the control concept fulfills the requirements and is able to effectively reduce high NOx peaks during transient operation.
