Investigation of impingement jet array heat transfer with high temperature ratio and high crossflow

Thesis

This thesis reports the development and commissioning of an experimental facility for investigating impingement cooling strategies relevant to gas turbine applications. The rig was modular, with precise thermal boundary control and a tailored instrumentation system for empirical determination of local and overall heat transfer coefficients. It extended the capability of published facilities by achieving higher temperature ratios than are commonly reported in canonical studies.

The facility was first validated by reproducing benchmark correlations from canonical impingement literature. Comparisons with established data confirmed stable, representative behaviour across a range of Reynolds numbers and ther- mal conditions.

Following validation, a corrugated jet plate configuration was assessed as a means of mitigating the adverse crossflow that typically degrades impingement performance. Experiments showed that this geometry exhibited less downstream degradation of Nusselt number compared to flat plate designs.

In parallel, a numerical study explored a novel supplementary approach based on in-plane thermal conduction. A simplified two-dimensional model of embedded high-conductivity inserts indicated potential for lowering peak surface temperatures and redistributing heat laterally where direct impingement is impractical.

These findings suggest that targeted geometric modifications and hybrid con- duction–convection strategies can enhance internal blade cooling performance and reduce reliance on film cooling in future gas turbine designs.

Authors: Ramm, W

• DOI: 10.5287/ora-1rv1dod9g
• Type of award: MSc by Research
• Level of award: Masters
• Awarding institution: University of Oxford
• Language: English
• Keywords: impingement cooling; turbomachinery
• Subjects: Heat Transfer; Mechanical engineering