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Instrumentation for high-bandwidth optical measurements in harsh reacting flows


TECHNOLOGY AREAS: Air Platform, Electronics

OBJECTIVE:  Enable significant improvements in the spatial and temporal resolution of critical phenomena in flowfields relevant to AF air-breathing combustion systems via development of innovative high-bandwidth planar or volumetric imaging  and quantitative measurements.

DESCRIPTION:  The development of air-breathing engines requires the utilization of advanced diagnostic methods capable of providing nonintrusive dynamic measurements in harsh, often high-temperature environments. These measurements can help engineers and engine designers investigate a variety of challenging problems, including flame-holding and flame-spreading in scramjet engines and augmenters, combustor ignition and relight, and jet-noise. To adequately understand these phenomena, engineers will increasingly rely upon advanced, nonintrusive, optical instrumentation capable of operating at high bandwidths and spatial resolution.  Desired measurements include but are not limited to parameters such as combustion intermediate species, gas static temperature, gas velocity and turbulence quantities at rates in excess of 50 kHz and resolved spatial scales less than a centimeter; with preference resolved spatial order in the millimeter scales in flowfields appropriate for the engineering development of propulsion subsystems.  Such flowfields may approximate those encountered in gas-turbines, augmenters, pulse detonation engines, and scramjets, as well as other portions of an air-breathing flowpath.  This announcement is broad in that a broad spectrum of methods may adequately address this topic, provided the proposed solution has the potential to radically improve data rates and resolution beyond the current state of the art. 

PHASE I:  Develop concepts for measurements systems of one or more flowfield quantities of relevance to AF related air-breathing engines. Complete proof-of-concept measurements in a laboratory-scale flowfield (reacting or nonreacting, depending on the application).  Demonstrate data acquisition rates in excess of 50 kHz.

PHASE II:  Implement the full diagnostic system in an appropriate challenging flowfield. Demonstrate data rates greater than 50 kHz, spatial resolution of scales less than one centimeter, with preference spatial resolution order in the millimeter scales and suitable planar or volumetric scales to adequately resolve the macroscale behavior of the demonstration flowfield.


Military Application:  Success will yield diagnostic systems that can be used for a variety of propulsion applications as noted above.

Commercial Application:  Such instrumentation can also be applied, potentially, to commercial engines (e.g., aircraft or stationary, power-generation gas turbines) or high-speed flowfields.

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