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

现代柴油发动机面临着满足日益严格的排放法规的许多挑战。采用控制策略来减少氮氧化物（NOx）和颗粒物（PM）的尾管排放。 由于柴油发动机的总体稀燃运行，在排气流中使用补充还原剂来中和NOx。 在汽车行业普遍采用的选择性催化还原（SCR）系统中，尿素作为还原剂被定量给料，而在稀NOx捕集系统中，燃料被周期性地定量给料。后一种系统在总体成本低方面优于SCR系统，但在效率和加药控制方面存在缺点。PM减少还需要补充燃料来再生柴油颗粒过滤器。后处理系统中的排气流体分布的均匀性强烈地影响NOx转化效率。 此外，不均匀的燃料分布增加了热应力，并导致严重的基板损坏。 郑博士的研究小组已经对外部燃料补充的主动流动控制进行了广泛的实验研究。为了在主动后处理系统中进行光学诊断，需要管道镜。 通过光学诊断，可以表征喷射角和喷雾贯穿距离，然后进行优化以防止壁面碰撞。利用红外成像技术，可以监测衬底的热分布，这可以帮助未来优化剂量策略。这对于气缸部件安装和精确对准是特别需要的，因为具有先进的新腔室设计的活塞的新设计和新的喷射器安装在对准中需要非常精确的匹配。轻微的错位可能对发动机部件有害。一个长的管道镜探头来验证正确的配合和发动机内的部件没有干扰是非常关键的。由于我们目前的研究重点是在先进的内燃机中使用生物燃料，因此需要对硬件进行修改，以设计新的活塞几何形状并使新的喷射器适应我们的发动机平台。

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.