Combustion system aerodynamics

With the continual drive for reduced fuel burn and reduced emissions it remains a key activity. The UTC invests significant time and effort into the experimental and numerical study of fundamental aero-thermal processes for individual components but it is also essential to understand the whole combustion system where components and processes interact.

The main areas of research currently include:

• Rich and lean burn system aerodynamics,
• Reduction of combustion system aerodynamic loss,
• OGV/pre-diffuser and dump gap aerodynamics,
• Fuel injector airflow feed and the feed to various cooling features,
• Novel and blue-sky combustor architectures, and
• Direct support for Rolls-Royce engine projects.

Several state of-the-art fully annular test facilities are employed to investigate combustion system aerodynamics. These include engine representative geometries and replicate the system from compressor exit to turbine entry. Importantly they include a bespoke 1½ stage axial compressor which generates representative inlet conditions. These facilities replicate individual component performance and importantly any potential component interactions in a system wide simulation. Aerodynamic measurements are typically made using a combination of pneumatic probes, hot-wire anemometry, PIV and CO2 gas tracing.

The resultant data, supported by CFD predictions, are used to study the overall flow field distribution and pressure losses throughout the combustion system and thereby develop and validate combustor aerodynamic designs. Importantly this provides total pressure loss data which is invaluable to the design process in order to estimate the system performance at an early stage before complex and expensive hot, high pressure tests are conducted (by Rolls-Royce).