Applications of modern medical imaging techniques for quantitative engineering flow measurements
Keywords: Mechanical Engineering.

Conventional engineering flow measurement techniques are usually limited to providing measurements at discrete points or planes and are either intrusive or require direct optical access. Obtaining full-field engineering flow measurements using existing techniques is difficult and seldom done. However, an accurate and detailed full-field understanding of relevant engineering flow processes is needed to optimize performance and/or test computational models. Modern medical imaging techniques offer the potential to provide noninvasive detailed, three-dimensional, full-field, information of relevant engineering flows. The work presented herein describes the methodology and application of modern medical imaging techniques, X-ray Computed Tomography (CT) and Magnetic Resonance Imagining (MRI), as quantitative measurement techniques to noninvasively acquire detailed full-field information of engineering flows with direct relevance to gas turbines. Results reveal three-dimensional characteristics and provide quantitative validation data for high-fidelity simulations. X-ray CT was used to acquire liquid mass concentration measurements of pressure swirl atomizers operating in ambient conditions. While modern medical X-ray CT systems have the capability of providing accurate detailed liquid-mass distribution measurements of sprays, such systems are not optimized for acquiring liquid-mass distribution measurements of sprays. Numerous parameters that influence the performance of an X-ray CT system were investigated to optimize a table-top X-ray CT system for imaging sprays. Result provide quantitative information in the near-field spray region of pressure-swirl atomizers and qualitative information of the features within the atomizers. Measurements were acquired up to a distance of approximately ten orifice diameters downstream of the pressure swirl atomizers. Magnetic Resonance Thermometry (MRT) coupled with Magnetic Resonance Velocimetry (MRV) was used to acquire temperature and velocity measurements of a conjugate jet-in-crossflow configuration. MRT is a recent development that has extended the capability of established MRI-based measurement techniques for investigating complex thermo-fluid flows with conjugate conditions. The 3D MRT measurements provide an overall film cooling effectiveness estimate that allows for the investigation the film cooling performance and conjugate heat transfer effects. Higher resolution 2D MRT results provide an estimate of the heat transfer coefficient. The experimental results were compared to ANSYS Fluent RANS simulations of the conjugate jet-in-crossflow configuration. Consistent with previous studies, the RANS simulations over-predicted the temperature distribution and did not properly capture the kidney-shaped structure due to the CVP. In general, X-ray CT provides the means to acquire accurate detailed three-dimensional liquid mass concentration measurements of two-phase flows and MRI provides the means to acquire detailed three-dimensional temperature and velocity measurements of liquid flows. Furthermore, these modern medical imaging techniques offer the potential of allowing for a more rapid design and development cycle, not only saving time and cost but providing a more detailed understanding of relevant engineering flow processes.