Coordination Funds

5595研究单元的主要目标是基于新颖的微观和宏观实验和模拟方法，为旋转正排量压缩机（RPDC）中油-制冷剂混合物的多相喘振和间隙流动开发一个有效的计算模型。该模型开发的一个关键先决条件是了解发生的流动模式（例如气泡流、浪涌流、雾流），这在很大程度上取决于流体混合物的热物理性质和操作边界条件。与移动间隙边界有关的小间隙高度（< 0.3 mm）使得需要将实验和数值流动分析结合起来。在圆柱形玻璃壳体内旋转体的通用实验模型上，测试了一种用于时空分辨测量两相气涌和间隙流动的新型激光光学框架，并与高分辨率流动模拟进行了比较。在此基础上，建立了带移动边界的窄间隙多相流的计算模型。所使用的油-冷媒混合物表现出强烈的不对称混合行为。对于这种混合物，首次系统准确地测量了相关的热物理性质，并将其转换为精确的状态方程和输运性质模型。模型的结构被设计成可转移到其他强不对称混合物中。此外，为了将模型应用于流动模拟，还需要注意可接受的计算速度。流体混合物热物理特性的新模型，以及多相涌流和间隙流的新计算方法，将有助于改进未来油-冷媒混合物高效RPDC的设计，从而有助于减少资源消耗。

The main objective of the Research Unit FOR 5595 is to develop a valid calculation model for multiphase surge and gap flows for oil-refrigerant mixtures in rotary positive displacement compressors (RPDC) based on novel microscopic and macroscopic approaches for experiments and simulations. A crucial prerequisite for this model development is the knowledge of the occurring flow patterns (e.g., bubbly, surge, mist flow), which depend significantly on the thermophysical properties of the fluid mixtures and operating boundary conditions. The small gap heights (< 0.3 mm) in connection with moving gap boundaries make a combined experimental and numerical flow analysis necessary. On the generic experimental model of a rotating body in a cylindrical glass housing, a new laser-optical framework for the spatially and temporally resolved measurement of the two-phase surge and gap flow is tested and compared with high-resolution flow simulations. Based on this, a calculation model for multiphase flow in narrow gaps with moving boundaries is developed. The oil-refrigerant mixtures used exhibit a strongly asymmetric mixing behavior. For such mixtures, the relevant thermophysical properties are measured systematically and accurately for the first time and are transferred into precise equations of state and transport property models. The structure of the models is designed to be transferable to other strongly asymmetric mixtures. Moreover, in order to apply the models in flow simulation, attention is paid to acceptable computational speed. The new models for the thermophysical properties of the fluid mixtures together with the new calculation approaches for the multiphase surge and gap flows will enable an improved design of efficient RPDC for oil-refrigerant mixtures in the future and, thus, contribute to the reduction of the consumption of resources.