Understanding of combustor flow fields is of great importance for the design and performance analysis of static and installed propulsion systems. One of the major drivers in combustor design is losses due to the fuel-air mixing and combustion inefficiencies. The combustor loss calculations and flow field structure (static and dynamic) for simple designs are normally retrieved from published data but for complex combustor flows, model testing is required. The major objective of these tests are to determine the flow structure and mixing efficiency along the entire length of the combustor, especially at the area of fuel injection. We propose an innovative non- intrusive technique to measure the internal combustor flow field density distribution and possibly the time averaged velocity through an unaltered combustor case. The technique is based on X-ray Compton backscatter and the resultant frequency shift of the scattered photons. This novel diagnostic approach has many advantages over similar scattering techniques and holds tremendous potential for commercialization. The technique requires absolutely no seeding, no special windows or access ports, uses basic physics and simple instrumentation, and will provide a portable, field useable tool for planar flowfield diagnosis. The XRD approach to flow field diagnostics will have unlimited applications to all systems with exposed or enclosed flowing gases or liquids. These could include aircraft propulsion systems, fluid transfer systems, hydrodynamic structures and industrial cooling systems. We believe that this system approach will be simple, easy to apply to a variety of diagnostic requirements. Additionally, there is a significant possibility that the system be commercialized to broader applications.
