Predicting ignitions of flammable gas mixtures caused by contact break discharges with dynamic source characteristics

利用动态源特性预测接触断开放电引起的易燃气体混合物的着火

• 批准号: 411446115
• 负责人: Professor Dr. Frank Berger
• 金额: --
• 依托单位: Leibniz-Institut für Plasmaforschung und Technologie e.V. (INP)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/411446115?language=en
• 关键词: Predicting; ignitions; flammable; gas; mixtures

The previous project focused on a multi-physical approach to contact break discharges in H2/air mixtures for constant current sources. An application-oriented model has been developed, which can predict ignition for a reference situation (30 V, 60 mA) in the context of explosion protection. Several experimental and modeling investigations on basic phenomena supported the understanding of underlying mechanisms and are unique in the field of explosion protection. It was shown that, in contrast to spark discharges with minimum ignition energy as ignition criterion, the investigated contact break discharges require a certain power density for a distinct time (ca. 200 µs) for a successful ignition. For this reason with the new project, the investigations are extended to dynamic current sources and the resulting dynamic behavior of the discharge and thus into the ignition-relevant hot gas kernel. The systematic investigation can be performed by varying the power transfer into the discharge and is realized with trapezoidal source characteristics and linear characteristics including a selected set of external circuit parameters. These source types are commonly used in practice. In order to verify the application-oriented model for dynamic source characteristics, it is necessary to analyze and simulate the effects of such characteristics. A 1D collisional radiative model simulation should be extended to a multi-level system of excited states and cadmium should be considered as a fraction in a H2/air mixture. Non-LTE calculations provide thermo-physical data, which will be used as input data in a 2D heat conduction model. This model is going to be extended to moving electrodes and dynamic currents as well and will allow to verify the application-oriented model for more complex situations. Reliability of the models will be further improved by a variation of material parameters using Zn as cathode material. It is also planned to improve the method by a more reliable contact device with drives outside the explosion chamber and an improved optical access for better schlieren diagnostics. The final goal of the project is to adopt the existing application-oriented model to the dynamic behavior of the discharge as well as the above-mentioned model optimizations including a selected set of external circuit parameters.

上一个项目的重点是一个多物理的方法来接触断氢/空气混合物的恒流源放电。一个面向应用的模型已经开发出来，它可以预测点火的参考情况（30 V，60 mA）的背景下，防爆。一些基本现象的实验和建模研究支持了对潜在机制的理解，在防爆领域是独一无二的。结果表明，与以最小点火能量作为点火判据的火花放电相比，所研究的接触断开放电需要一定的功率密度持续不同的时间（约1000 ms）。200 µs），以便成功点火。由于这个原因，在新的项目中，研究扩展到动态电流源和由此产生的放电动态行为，从而进入点火相关的热气核。系统的调查可以通过改变功率转移到放电，并实现了梯形源特性和线性特性，包括一组选定的外部电路参数。这些源类型通常在实践中使用。为了验证面向应用的动态源特性模型，有必要对这些特性的影响进行分析和仿真。一维碰撞辐射模型模拟应扩展到激发态的多能级系统，镉应被视为H2/空气混合物中的一部分。非LTE计算提供热物理数据，这些数据将用作2D热传导模型的输入数据。该模型将扩展到移动电极和动态电流，并将允许验证更复杂情况下的面向应用的模型。采用Zn作为阴极材料，通过改变材料参数，可进一步提高模型的可靠性。还计划改进该方法，在爆炸室外安装一个更可靠的接触装置，并改进光学通道，以更好地进行纹影诊断。该项目的最终目标是采用现有的面向应用的模型的放电的动态行为，以及上述模型的优化，包括一组选定的外部电路参数。