Abstract

Finite volume methods were used to study the process of gas expansion in the stage of a turboexpander unit (TEU) in a three-dimensional, nonstationary setting. The main objectives of the work are to verify the calculation methodology based on a real experiment, to obtain a qualitative and quantitative agreement of data for further studies of the processes occurring in the flow path of the stage of a turboexpander unit, namely, phase transitions during condensation of impurities in the bulk. Due to the fact that the experiment is only preliminary tests, there is no reliable data on the intermediate values of the macroparameters; therefore, the verification of the proposed method was carried out only in terms of the temperature at the outlet from the diffuser and the isentropic efficiency. The calculation technique used in this work, thanks to the use of sliding interfaces, made it possible to study the turboexpander unit not in parts but with the help of a unified calculation model, taking into account the leaks and overflows of the working fluid (helium). In the course of calculations, the fields of velocity, pressure, and temperature were obtained in the longitudinal and cross sections of the turboexpander unit as well as on its walls. A simplified h, s-process diagram, and the values of isentropic efficiency are determined for several points. The proposed calculation method, applied for a specific model of a turboexpander unit, can be extrapolated to other variants of the flow paths of microturbine expander units for boundary conditions and operating modes close to the original variant. To prepare an extended calculation method, it is necessary to carry out additional studies as well as to establish the limits of applicability of the finite volume method on a larger data set.

中文翻译：

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透平膨胀机装置气体膨胀过程的有限体积法数值模拟

摘要

有限体积方法用于研究涡轮膨胀机 (TEU) 阶段在三维非固定环境中的气体膨胀过程。这项工作的主要目标是验证基于实际实验的计算方法，获得定性和定量数据的一致性，以进一步研究涡轮膨胀机单元级流路中发生的过程，即相变在大量杂质的冷凝过程中。由于实验只是初步测试，宏观参数的中间值没有可靠的数据；因此，仅在扩散器出口处的温度和等熵效率方面对所提出的方法进行了验证。在这项工作中使用的计算技术，由于使用了滑动界面，因此可以在统一计算模型的帮助下研究涡轮膨胀机单元，而不是部分研究，同时考虑到工作流体（氦气）的泄漏和溢出。在计算过程中，获得了透平膨胀机机组纵向和横截面及其壁上的速度场、压力场和温度场。一个简化的h、s 过程图和等熵效率的值由几个点确定。所提出的计算方法适用于涡轮膨胀机单元的特定模型，可以外推到微涡轮膨胀机单元流动路径的其他变体，以获得接近原始变体的边界条件和操作模式。为了准备扩展的计算方法，有必要进行额外的研究，并在更大的数据集上建立有限体积方法的适用范围。