Automated in service and permanent prevention, removal and detection of vessel hull fouling using a sparse network of guided ultrasound sensors (VESSEL CLEAN)

船体结垢是造成船舶燃料消耗和碳排放过剩的最大原因，一年的排放量可高达50%。尽管全球商船队每年在污染预防和清洁方面的支出约为60亿英镑，但每年仍要花费80亿英镑的额外燃料成本，并产生7000万吨额外的二氧化碳。该项目的目标是基于嵌入船体的低频（~40kHz）主动超声压缩波传感器的分布式稀疏网络，开发一种用于永久性污垢预防、检测和清除的现役自动化系统。在正常运行时，会在整个船体内激发暂时但连续的准强制驻波，其功率足以使超声波从表面天线渗漏到水中产生空化。空化会在生物膜形成时迅速去除它们的附着表面（即微污染），从而防止污垢积聚（即大污染）。频率将被扫描，网络的不同部分将依次激发扫描整个船体的天线。该程序将去除船体和螺旋桨表面100%以上的生物膜，连续波浪的最小开/关时间，即最小平均功率时间。周期性地，脉冲波将被激发以检测由于不完美的生物膜去除引起的意外大污染，然后将通过暂时增加连续开/关时间来消除，然后恢复正常操作。研究存在一种可能性，即利用亚空化水平的超声力场阻止生物污垢的初始形成，从而进一步降低平均功耗。

Hull fouling is the largest contributor to excess fuel consumption and carbon emissions by ships, which can be up to 50% over a year. In spite of a global expenditure of some £6bn pa on fouling prevention and cleaning amongst the global merchant fleet, fouling still costs £8bn pa in additional fuel costs and produces 70m tonnes of additional carbon dioxide. The project goal is to develop an in service automated system for permanent fouling prevention, detection and removal based on a distributed, sparse network of low frequency (~40kHz) active ultrasonic compressional wave sensors embedded in a ship hull. In normal operation, temporary but continuous quasi forced standing waves will be excited throughout the hull, with power sufficient for ultrasound leakage into water from surface antinodes to produce cavitation. Cavitation will remove thin biofilms (i.e. microfouling) and their adhesion surface as fast as they are formed, thus preventing fouling build-up i.e. macrofouling. The frequency will be swept and different parts of the network sequentially excited scan the antinodes through 100% of the hull. This programme will remove biofilm over 100% of the hull and propeller surface, with minimum ON/OFF time for the continuous waves i.e. minimum time averaged power. Periodically, pulsed waves will be excited to detect accidental macrofouling up caused by imperfect biofilm removal, which will then be removed by a temporary increase in the continuous ON/OFF time followed by a return to normal operation. There exists the possibility, to be researched that the intial formation of biofouling can be prevented by ultrasonic force fields at sub-cavitation levels, further reducing the average power consumption.