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Theoretical Modelling of Ingress in Gas Turbine Rim Seals.

燃气轮机边缘密封侵入的理论模型。

基本信息

批准号：
2127975
负责人：
金额：
--
依托单位：
University of Bath
依托单位国家：
英国
项目类别：
Studentship
财政年份：
2018
资助国家：
英国
起止时间：
2018 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=studentship-2127975
关键词：
Theoretical Modelling Ingress Gas Turbine

项目摘要

Engineers aim to improve the efficiency of gas turbines without sacrificing the life of materials. Ingress is the phenomenon where hot gas from the mainstream flow is ingested into the wheel-space between the stationary casing and the adjacent rotating disc. To prevent or reduce ingress, rim seals are fitted at the periphery of the discs and sealing air, which is directly bled from the compressor, pressurises the internal cavity. However, using too much sealing air reduces the efficiency, while too little can damage the materials due to high temperatures. Siemens currently use the University of Bath Orifice Model to design rim seals for their engines. Here, only the inertial effects are taken into account, while discharge coefficients are used to account for the viscous effects and other related losses. These coefficients cannot be determined theoretically and they are treated as empirical constants for each seal. The Orifice Model is used to predict ingress, and although it is in good agreement with concentration based experimental results, problems with pressure difference predictions arise for different rim seals geometries (i.e., axial and radial rim seals). Recently, Savov and Atkins proposed an alternative approach, where turbulent diffusion is used to model ingress as a viscous problem while ignoring the inertial effects. This project aims to develop a new Control Volume Model for the prediction of ingress by uniting the Orifice Model and the viscous terms of turbulent diffusion model which are currently ignored by the Bath approach. The new model is expected to solve the problem of the pressure difference prediction while maintaining good agreement with concentration based effectiveness measurements. The student will combine the experimental and theoretical parts for a better understanding and interpretation of the results. Furthermore, it is desirable to involve CFD for validation purposes, however, at this stage, it is undecided to what extent. At the start of the project the student will cover the available literature around ingress, while conducting experiments in the 1.5-stage turbine rig with the supervision of an experienced operator; later the student will be the main operator of the rig. The second phase includes the collection of pressure distribution and concentration effectiveness data which will inform the modelling. A parametric study of Siemens specific rim seal design will then be conducted. Finally, during the third phase, which overlaps with the second, the student and the supervisor will incorporate the experimental test results into the new theoretical model for validation.Throughout the project, it is expected that colleagues from the Turbomachinery Research Centre (TRC) will be involved for the validation and verification of the model by comparing their results and improving their models and codes. This will constitute a 3.5 - year PhD programme and by 2022 a new Control Volume Model will be established.

工程师们的目标是在不牺牲材料寿命的情况下提高燃气轮机的效率。进气是主流中的热气进入固定壳体和相邻旋转盘之间的轴距的现象。为了防止或减少进入，边缘密封件安装在盘的外围，并且直接从压缩机流血的的密封空气对内腔加压。然而，使用太多的密封空气会降低效率，而太少的密封空气会因高温而损坏材料。西门子目前使用巴斯大学的孔板模型来设计其发动机的边缘密封。这里只考虑惯性效应，而流量系数用于考虑粘性效应和其他相关损失。这些系数不能从理论上确定，它们被视为每个密封的经验常数。孔板模型用于预测入口，尽管它与基于浓度的实验结果非常一致，但对于不同的边缘密封几何形状（即，轴向和径向边缘密封）。最近，Savov和阿特金斯提出了一种替代方法，其中湍流扩散被用于将入口建模为粘性问题，同时忽略惯性效应。该项目旨在通过结合孔板模型和目前被巴斯方法忽视的湍流扩散模型的粘性项，开发一种新的控制体积模型来预测入口。新模型有望解决压差预测的问题，同时保持良好的协议与浓度为基础的有效性测量。学生将联合收割机结合实验和理论部分，以便更好地理解和解释结果。此外，最好将CFD用于验证目的，但是，在此阶段，尚未决定在何种程度上。在项目开始时，学生将涵盖有关入口的可用文献，同时在1.5级涡轮机试验台上进行实验，并由经验丰富的操作员进行监督;之后，学生将成为试验台的主要操作员。第二阶段包括收集压力分布和浓度有效性数据，这些数据将为建模提供信息。然后将对西门子特定边缘密封设计进行参数研究。最后，在与第二阶段重叠的第三阶段，学生和导师将把实验测试结果结合到新的理论模型中进行验证。在整个项目中，预计涡轮机械研究中心（TRC）的同事将通过比较他们的结果并改进他们的模型和代码来参与模型的验证和验证。这将构成一个3.5年的博士课程，到2022年将建立一个新的控制量模型。