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The ACARE 2020 vision for commercial transport aircraft targets a 50% reduction per passenger kilometer in fuel consumption and CO2 emissions, with a 20-25% reduction to be achieved through airframe improvements. This step change in performance is dependent on the successful integration and down-selection of breakthrough technologies at early stage of aircraft development process, supported by advanced multidisciplinary design capabilities. Conceptual design capabilities, integrating more disciplines are routinely used at Future Project Office. The challenge considered here is to transition smoothly from conceptual to preliminary design whilst maintaining a true multidisciplinary approach. The design space must be progressively constrained, whilst at the same time increasing the level of modelling fidelity and keeping as many design options open for as long as possible.

Experimental studies were performed to gain a better understanding of the behaviour of water in jet fuel at low temperatures. The transition of water in fuel from dissolved water to free water, and its subsequent precipitation behaviour when the fuel was cooled down, were investigated using a 20 litre glass-windowed aluminium tank. The effects of cooled internal surfaces were explored with chilled plates at the top and bottom of the aluminium tank. The tank was fitted with an array of thermocouples, which allowed horizontal and vertical temperature profiles to be measured. A laser visualisation system incorporating image processing software was used to capture images inside the simulated tank without interfering with the convective flow of the fuel. Fuel will precipitate any excess dissolved water when cooled below the saturation temperature. The excess water may then appear in the form of fine water droplets or ice particles as a fine cloud (fog).

Despite past research programs focusing on tropical convection, the explicit studies of high ice water content (IWC) regions in Mesoscale Convective Systems (MCS) are rare, although high IWC conditions are potentially encountered by commercial aircraft during multiple in-service engine powerloss and airdata probe events. To gather quantitative data in high IWC regions, a multi-year international HAIC/HIWC (High Altitude Ice Crystals / High Ice Water Content) field project has been designed including a first field campaign conducted out of Darwin (Australia) in 2014. The airborne instrumentation included a new reference bulk water content measurement probe and optical array probes (OAP) recording 2D images of encountered ice crystals. The study herein focuses on ice crystal size properties in high IWC regions, analyzing in detail the 2D image data from the particle measuring probes.