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We report the development of optimized fluorescent dye-doped tracer particles for gas-phase particle image velocimetry (PIV) and their use to eliminate ‘flare’ from the images obtained. In such applications, micron-sized tracer particles are normally required to accurately follow the flow. However, as the tracer size is reduced the amount of light incident on the particle diminishes and consequently the intensity of emitted light (fluorescence). Hence, there is a requirement to identify dyes with high quantum yield that can be dissolved in conventional tracer media at high concentrations. We describe the selection and characterization of a highly fluorescent blue-emitting dye, Bis-MSB, using a novel method, employing stabilized micro-emulsions, to emulate the fluorescence properties of tracer particles. We present the results of PIV experiments, using 1 µm tracer particles of o-xylene doped with Bis-MSB, in which elastically scattered ‘flare’ has been successfully removed from the images using an appropriate optical filter.

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Two-and three-component multi-phase air/fuel measurements have been performed on a GDI injector. UV-excitable fluorescent tracers have been used to seed the gas phase, and the naturally occurring droplets in the fuel are the other phase. A high-pressure multi-hole GDI injector was mounted in a rig with a glass barrel to simulate the engine cylinder and provide optical access. Images were obtained under controlled conditions of fuel pressure and injection duration. Flow phase and pulse order have been determined from a single 3CCD colour camera. Suitable corrective processes have been adapted and implemented to account for crosstalk and chromatic aberrations so that the uncertainty of the velocity vectors produced is comparable to that of conventional PIV using 532 nm illumination. Multi-phase air/fuel vector maps have been produced. A second colour camera has been added to obtain stereo velocity measurements providing previously unavailable simultaneous information on the multi-phase (fuel/air) interaction with three velocity components.

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Precision is a very high resolution earth observation imager that delivers high quality and high area coverage for pansharpened imagery and has been developed by SSTL as part of a ESAs Incubed programme. Over the last few years the development has been progressing through the design phase and development phase and is now undergoing PFM manufacture and test.An overview of the instrument design is presented alongside the key design decisions that led to the overall specification. This resulted in a compact design that utilises a novel sensor and innovative opto-mechanical techniques to achieve a swath of >9.5km and a GSD in panchromatic channel of 0.6m native. The PAN channel is used to sharpen four 1.2m GSD multi-spectral channels and through post-processing sub 0.5m GSD is achievable. This allows for its integration into compact spacecraft in order to support affordable operations as a stand-alone unit or in constellations providing higher temporal resolution. Anticipated applications include mapping, surveillance, infrastructure and asset monitoring, disaster monitoring, insurance and loss adjustment. The ability to achieve improved resolution through processing lends itself to high performance small satellites with capabilities for on board processing to allow near real time feature recognition and the use of ISL' for high availability to meet the customer needs of today.