Aerodynamic Loss Co-Relations and Flow- Field Investigations of a Transonic Film- Cooled Nozzle Guide Vane

• Main Author: Leung, Pak Wing
• Format: Others
• Language: English
• Published: KTH, Kraft- och värmeteknologi 2015
• Subjects: gas turbine; aerodynamics; secondary flow; external cooling; film cooling; aerodynamic loss; high pressure turbine; nozzle guide vane
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-162130

Over the last two decades, most developed countries have reached a consensus that greener energy production is necessary for the world, due to the climate changes and limited fossil fuel resources. More efficient turbine is desirable and can be archived by higher turbine-inlet temperature (TIT). However, it is difficult for nozzle guide vane (NGV), which is the first stage after combustion chamber, to withstand a very high temperature. Thus, cooling methods such as film cooling have to be implemented. Film-cooled NGV of an annular sector cascade (ASC) is studied in this thesis, for getting comprehensive calculation of vorticity, and analyzing applicability of existing loss models, namely Hartsel model and Young & Wilcock model. The flow-field calculation methods from previously published studies are reviewed. Literatures focusing on Hartsel model and Young & Wilcock model are studied. Measurement data from previously published studies are analyzed and compared with the loss models. In order to get experience of how measurements take place, participation of a test run experiment is involved. Calculation of flow vector has been evaluated and modified. Actual flow angle is introduced when calculating velocity components. Thus, more exact results are obtained from the new method. Calculation of vorticity has been evaluated and made more comprehensive. Vorticity components as well as magnitude of total streamwise vorticity are calculated and visualized. Vorticity is higher and more extensive for fully cooled case than uncooled case. Highest vorticity is found at regions near the hub, tip and TE. Axial and circumferential vorticities show similar patterns, while the radial vorticity is relatively simpler. Compressibility is introduced as a new method when calculating circumferential and radial vorticities, resulting more extensive and higher vorticities than results from incompressible solutions. Hartsel model and Young & Wilcock model have been evaluated and compared to the ASC to see the applicability of the models. In general, Hartsel model cannot agree with the ASC to a satisfactory level and thus cannot be applied. Coolant velocity is found to be the dominant factor of Hartsel model. Young & Wilcock model may match SS1 and SS2 cases, or even PS and SH4 cases, but cannot match TE case. The applicability of Young & Wilcock model is much dependent on the location of cooling rows.