Investigation of vortex ring-like structures in internal combustion engines, taking into account thermal and confinement effects

这一建议是有关的非平凡的推广以前开发的模型，以分析多相涡旋环状结构考虑热，旋流和约束效应。热效应包括在载流子相中存在热梯度，以及液滴的加热和蒸发。约束效应将考虑到外壳中墙壁的贡献，这在内燃机建模过程中尤为重要。将使用三种建模方法：直接数值模拟（DNS），全拉格朗日方法（Osiptsov-Lagrangian方法）和渐近/解析模型。迄今为止，所有这些模拟涡环结构的方法的发展主要集中在可以忽略上述热效应和约束效应的情况下。在本项目中，上述三种方法都将加以推广，以考虑热效应和约束效应。这种推广不是微不足道的，特别是在完整的拉格朗日和渐近/解析方法的情况下，据我们所知，没有人试图这样做。建模将特别侧重于可燃气体和汽油内燃机，但预计将开发的方法可以推广到更广泛的应用范围。该项目的建模工作将由上述发动机中涡环状结构的实验研究补充。直接喷射气体和液体燃料喷雾（LPG/CNG和汽油发动机）和连续相的运动将在一个封闭的静态观察室内使用基于激光的测量技术进行研究。将获得描述注入速度分布和液滴浓度的新数据，以支持建模方法。实验研究将考虑加热和限制。工作的初始阶段将集中在可燃气体内燃机上，这将使我们能够将分析限制在单相流上，使用DNS和渐近/分析方法。在这个阶段考虑的主要新效应将是在外壳、漩涡和内墙中存在的温度梯度。在下一阶段，上述模型将被推广，以考虑到外壳中液体喷雾的影响。这种多相流建模的新方法将结合先前EPSRC项目EP/F069855/1所开发的射流和液滴破裂模型。在适当的情况下，由完整拉格朗日模型和解析/渐近模型得出的预测将与基于瞬态涡旋环状结构的DNS模拟的预测进行比较。我们还将研究将完整拉格朗日模型和解析/渐近模型纳入研究CFD代码KIVA 3和商业CFD代码VECTIS和FLUENT的可行性。数值和分析模型的预测将与在可燃气体和类似汽油发动机条件下获得的内部实验结果进行验证。将研究结果对这些发动机过程优化的适用性。这将是一个由外部访问研究人员参与的合作项目，他们的专业知识主要集中在数值和解析/渐近涡旋环模型的发展以及完整的拉格朗日方法。该项目将确保物理和数学模型的质量达到新的水平，正如之前资助的EPSRC项目EP/E047912/1和目前正在进行的项目EP/K005758/1所开发的那样。预计该项目的工作与目前正在进行的EPSRC项目EP/K005758/1之间的时间重叠将确保该方向研究的连续性。

This proposal is concerned with the non-trivial generalisation of previously-developed models for the analysis of multi-phase vortex ring-like structures to take into account thermal, swirl and confinement effects. Thermal effects include the presence of thermal gradients in the carrier phase, and heating and evaporation of droplets. Confinement effects will take into account the contribution of walls in the enclosure, which are particularly important in the case of modelling processes in internal combustion engines. Three modelling approaches will be used: Direct Numerical Simulation (DNS), the full Lagrangian approach (the Osiptsov-Lagrangian method) and asymptotic/analytical models. Development of all these approaches for modelling vortex ring-like structures has so far been mainly focused on cases when the contribution of the above-mentioned thermal and confinement effects can be ignored. In the present project, all three above-mentioned approaches will be generalised to take thermal and confinement effects into account. This generalisation is not trivial, especially in the case of the full Lagrangian and asymptotic/analytical approach, and nobody, to the best of our knowledge, has attempted to do this. Modelling will be specifically focused on combustible gas and gasoline internal combustion engines, but it is expected that the methods to be developed could be generalised to a much wider range of applications. Modelling work on the project will be complemented by experimental studies of vortex ring-like structures in the above-mentioned engines. The direct injection of gas and liquid fuel sprays (LPG/CNG and gasoline engines) and the motions of the continuous phase will be studied in a closed, quiescent observation chamber using laser-based measurement techniques. New data to describe the injection velocity profile and droplet concentration will be acquired to support the modelling approaches. The experimental study will take into account heating and confinement. The initial stage of the work will be focused on combustible gas internal combustion engines, which will allow us to restrict our analysis to a one-phase flow, using the DNS and asymptotic/analytical approach. The main new effect taken into account at this stage will be the presence of temperature gradients in the enclosure, swirl and the presence of interior walls. At the next stage the above model will be generalised to take into account the effects of liquid sprays in the enclosure. This new approach to the modelling of multiphase flows will incorporate the jet and droplet break-up models developed as a result of work on the previous EPSRC project EP/F069855/1. Where appropriate, predictions resulting from the full Lagrangian and analytical/asymptotic models will be compared with predictions based on DNS simulations of transient vortex ring-like structures. We will also investigate the feasibility of incorporating of the full Lagrangian and analytic/asymptotic models into the research CFD code KIVA 3 and commercial CFD codes VECTIS and FLUENT. Predictions from numerical and analytical models will be validated against in-house experimental results obtained in combustible gas and gasoline engine-like conditions. The applicability of the results to the optimisation of processes in these engines will be investigated. This will be a collaborative project involving external visiting researchers whose expertise is mainly focused on the development of the numerical and analytical/asymptotic vortex ring models and the full Lagrangian method. This project will ensure a qualitatively new level of physical and mathematical models, as developed in the previously-funded EPSRC project EP/E047912/1, and the currently active project EP/K005758/1. The anticipated overlap in time between the work on this project and currently active EPSRC project EP/K005758/1 will ensure the continuity of research in this direction.