A Flexible Fibre Optic Borescope for Diagnosis of Active Controlled After-treatment and Engine Implementations

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Modern diesel engines are facing many challenges of meeting the increasingly stringent emission regulations. Control strategies are employed to reduce tail-pipe emissions of the nitrogen oxides (NOx) and particulate matter (PM). Due to the overall lean operation of diesel engine, supplemental reductant is used in the exhaust stream to neutralize NOx. In a selective catalytic reduction (SCR) system that commonly adopted by automotive industry to meet 2014 beyond emission standards, urea is dosed as the reductant, while in a lean NOx trap system, fuel is dosing periodically. The later system has the advantages over the SCR system for overall low cost but disadvantages in the efficiency and dosing control. PM reduction also requires supplemental fuel to regenerate the diesel particulate filter. The homogeneity of the exhaust fluid distribution in the after-treatment systems strongly impacts the NOx conversion efficiency. Moreover, the non-homogeneous fuel distribution increases the thermal stress and causes severe damage of the substrate. Extensive empirical investigations of active flow control with external fuel supplement have been carried out in Dr. Zheng's group. A borescope is needed for the purpose of optical diagnosis in the active aftertreatment system. Through optical diagnosis, the injection angle and the spray penetration can be characterized and then be optimized to prevent wall impingement. With infrared imaging technique, the thermal distribution of the substrate can be monitored, which can future help the optimization of the dosing strategies. This is particularly needed for cylinder component installation and precise alignment, since the new design of piston with advanced new chamber design and new injector installation require very precise matching in the alignment. A slight mis-alignment could be detrimental for the engine components. A long borescope probe to verify the correct mating and lack of interference of components within the engine is very critical. With our current research focus in using biofuels in advanced combustion engines, the need is intensified in hardware modifications to design new piston geometries and adapt new injectors to our engine platform.