To develop a non-equilibrium wet steam throughflow calculation method, including modelling of all the loss-generating two-phase phenomena

拟议的项目将建立在阿尔斯通（现为通用电气）在剑桥支持的最新工作的基础上，并与正在进行的未来常规电力研究联盟项目相结合，该项目也有一个位于剑桥的湿蒸汽组件。该项目的目标如下：（a）开发一种非平衡湿蒸汽通流计算方法，包括模拟所有产生损失的两相现象。这项工作的基础将由目前阿尔斯通支持的剑桥博士项目提供，该项目现已接近完成。目前的状况是，非平衡例程和尾流斩波模型已被包括在流线曲率代码，使全球的冷凝涡轮机内的影响进行预测，连同液滴尺寸谱。然而，这种方法是有价值的，在设计阶段和作为一种研究工具，主机的额外的两相现象需要进行建模。其中包括：非均匀凝结的贡献;液滴在涡轮机叶片上的惯性冲击和湍流输送的沉积;在剪切力和离心力作用下的膜迁移;叶片后缘处的粗水形成;计算不同现象之间的损失及其分布，例如热松弛，雾滴阻力，粗水冲击的制动效果等。这些现象中有许多存在模型（特别是由于Gyarmathy的开创性工作[1]），但是有些是基于一维假设的，并且需要扩展和修改以包含到（二维）流线曲率代码中。剑桥在这一领域有相当丰富的经验，包括对注水压缩机中类似现象的建模[2]。(b)通流代码的应用提供了一个全面的研究机器几何形状，操作条件和模型假设如何影响损失的整体大小和它们在不同现象之间的分布。例如，LP涡轮机入口温度的变化可能会改变冷凝的位置，从而使其以非常不同的膨胀率历史发生。这可能对液滴尺寸分布产生重大影响，而液滴尺寸分布又将影响上文（a）中列出的所有其他两相过程。这样的研究将需要与我们的工业合作伙伴进行大量的互动，因此CASE学生奖学金为这项工作提供了一个理想的框架。除了（a）和（B）之外，还打算在工作中增加一个额外的组成部分，其确切性质应取决于博士生的偏好和背景。可能包括（i）在STEAMBLOCK中包含速度滑移建模（剑桥最近开发的三维非定常湿蒸汽代码）和应用于研究各种配置中的惯性弛豫效应（例如，皮托管测量的解释）;（ii）对非均匀效应的作用的综合研究;（iii）基本相变建模（即，成核和液滴生长研究）。参考文献[1] Gyarmathy，G.，1962. Nassdampfturbine的基本理论。博士论文（也是CEGB翻译：“湿蒸汽涡轮机理论的基础”，T。781）。[2]白色，A.J.，Meacock，A. J.，2011. "包括速度滑移效应的湿压缩分析"，J. Eng.燃气轮机动力133（8），081701

The proposed project will build on recent work supported by Alstom (now General Electric) at Cambridge and integrate with the ongoing Future Conventional Power Research Consortium project, which also has a wet steam component based in Cambridge. The objectives of the project are as follows:(a) To develop a non-equilibrium wet steam throughflow calculation method, including modelling of all the loss-generating two-phase phenomena. The basis for this work will be provided by a current Alstom-supported PhD project at Cambridge that is now nearing completion. The current status is that non-equilibrium routines and wake-chopping models have been included within a streamline curvature code, enabling the global effects of condensation within turbines to be predicted, together with droplet size spectra. However, for this method to be of value both at the design stage and as a research tool, a host of additional two-phase phenomena need to be modelled. These include: contributions from heterogeneous condensation; deposition of droplets onto turbine blades by inertial impact and turbulent transport; migration of films under the action of shear and centrifugal forces; coarse water formation at blade trailing edges; computation of losses and their distribution between different phenomena such as thermal relaxation, fog-droplet drag, the braking effect of coarse water impaction etc. Models exist for many of these phenomena (notably due to the pioneering work of Gyarmathy [1]), but some are based on one-dimensional assumptions and require extension and adaption for inclusion into the (two-dimensional) streamline curvature code. Cambridge has considerable experience in this area, including the modelling of similar phenomena in water-injected compressors [2].(b) Application of the throughflow code to provide a comprehensive study of how machine geometry, operating conditions and model assumptions influence the overall magnitude of losses and their distribution between the different phenomena. For example, changes to the LP turbine inlet temperature are likely to change the location of condensation such that it occurs with a very different expansion rate history. This may have a significant effect on the droplet size distribution, which in turn will affect all the other two-phase processes listed in (a) above. Such a study will require significant interaction with our industrial partners, and the CASE studentship thus provides an ideal framework for this undertaking.In addition to (a) and (b) it is intended that there should be an additional component to the work, the precise nature of which should depend on the preferences and background of the PhD student.Possibilities include (i) inclusion of velocity slip modelling within STEAMBLOCK (the 3D unsteady wet steam code recently developed at Cambridge) and application to study inertial relaxation effects in a variety of configurations (e.g., interpretation of Pitot tube measurements); (ii) a comprehensive study of the role of heterogeneous effects; (iii) fundamental phase-change modelling (i.e., nucleation and droplet growth studies).References[1] Gyarmathy, G., 1962. "Grundlagen einer Theorie der Nassdampfturbine". PhD Thesis (alsoCEGB translation : "Bases for a Theory for Wet Steam Rurbines", T. 781).[2] White, A.J., and Meacock, A. J., 2011. "Wet Compression Analysis Including Velocity Slip Effects", J. Eng. Gas Turbines Power 133(8), 081701