FOR 2687: Cyclic variations in highly optimized hydrogen-fueled spark-ignition engines: experiment and simulation of a multi-scale causal chain

FOR 2687：高度优化的氢燃料火花点火发动机的循环变化：多尺度因果链的实验和模拟

• 批准号: 349537577
• 金额: --
• 依托单位: Lehrstuhl für Thermodynamik mobiler Energiewandlungssysteme (TME)
• 依托单位国家: 德国
• 项目类别: Research Units
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/349537577?language=en
• 关键词: 2687; Cyclic; variations; highly; optimized

The goal of the Research Unit FOR 2687 is to understand the cause-and-effect chain that leads to cyclic variations in highly optimized spark-ignition engines. In the first funding period, conventional gasoline-type fuels where investigated. The second funding period will exclusively consider hydrogen as a fuel. The very different physical-chemical properties of hydrogen require significant advances in the methods and models that were successfully developed in the first funding period. In spark-ignited engines, the cylinder pressure traces exhibit seemingly random variations from cycle to cycle, and thus characteristic metrics like peak pressure, heat release rate and mean effective pressure all vary. Combustion anomalies like misfire, pre-ignition and knocking also can be understood as extreme forms of cyclic variations. They are fundamental limitations for optimizing engine efficiency. The variations in the combustion result from the interaction of various extrinsic and intrinsic phenomena, whose connection in time and space is analyzed here in a cause-and-effect chain. The overarching goal of the FOR 2687 is to develop a better understanding, and through this better models and simulation methods, for this chain. Compared to the hydrocarbons considered thus far, hydrogen has very different physical-chemical properties. In particular, its flammability limits are extremely wide, the density and the minimum ignition energy are low, and premixed hydrogen flame have strong thermo-diffusive instabilities. These properties significantly impact the cause-and-effect chain leading to cyclic variations, which is to be investigated in the second funding period. To this end the Research Unit utilizes experiments and simulations. The former mainly are optical imaging diagnostics that capture phenomena like flow, hydrogen injection, mixing and combustion with high spatio-temporal resolution. The experiments are performed in optically accessible research engines and in a high-pressure cell. Large eddy simulation (LES) and direct numerical simulation (DNS) are used with suitable chosen and purpose-developed numerical schemes and models. This is augmented by lower-dimensional models. Based on the experimentally validated results, the causality of cyclic variations is traced back in time. For this, novel methods for analyzing partially coherent complex flows are developed. Energy process engineering is a research focus in all four locations of this Research Unit, RWTH Aachen, U .Duisburg-Essen, TU Darmstadt, and U. Stuttgart. The rich opportunities afforded by this to young scientists are complemented by a number of networking and professional-development events organized by the Research Unit that also actively supports efforts towards equal opportunities for all scientists.

研究单位FOR 2687的目标是了解导致高度优化的火花点火发动机循环变化的因果链。在第一个供资期间，对常规汽油类燃料进行了调查。第二个供资期将专门考虑将氢作为燃料。氢的物理化学性质非常不同，需要在第一个供资期成功开发的方法和模型方面取得重大进展。在火花点火式发动机中，气缸压力迹线从一个循环到另一个循环表现出看似随机的变化，因此，诸如峰值压力、放热率和平均有效压力的特征度量都变化。燃烧异常，如失火，提前点火和爆震也可以被理解为极端形式的循环变化。它们是优化发动机效率的基本限制。燃烧中的变化是各种外在和内在现象相互作用的结果，在此以因果链分析其在时间和空间上的联系。FOR 2687的总体目标是更好地理解这条链，并通过更好的模型和模拟方法。与迄今为止所考虑的碳氢化合物相比，氢具有非常不同的物理化学性质。特别是其可燃极限极宽，密度和最小点火能量低，预混氢火焰具有很强的热扩散不稳定性。这些特性对导致周期性变化的因果链产生重大影响，将在第二个供资期对此进行调查。为此，研究股利用实验和模拟。前者主要是光学成像诊断，以高时空分辨率捕获流动，氢气喷射，混合和燃烧等现象。实验在光学可访问的研究引擎和高压细胞中进行。大涡模拟（LES）和直接数值模拟（DNS）使用合适的选择和专门开发的数值方案和模型。这是由低维模型增强。基于实验验证的结果，周期变化的因果关系追溯到时间。为此，开发了分析部分相干复杂流动的新方法。 能源过程工程是该研究单位的四个研究中心的研究重点，RWTH亚琛，U .Duisburg-Essen，TU达姆施塔特和U.斯图加特。这为青年科学家提供了丰富的机会，研究股还组织了一些网络和专业发展活动，积极支持为所有科学家提供平等机会的努力。