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

船体污垢是船舶过度燃油消耗和碳排放的最大贡献者，一年内可能高达50%。尽管全球商船船队在防污和清洁方面的全球支出约为60亿GB pa，但污染仍需花费80亿GB pa的额外燃料成本，并产生7000万吨额外的二氧化碳。该项目的目标是开发一个使用中的自动化系统，用于永久污垢的预防、检测和清除，该系统基于嵌入船体中的低频(~40 kHz)有源超声波纵波传感器的分布式稀疏网络。在正常操作中，临时但连续的准强迫驻波将在整个船体中被激发，功率足以使超声波从表面反极渗入水中产生空化。空化作用会在形成薄层生物膜(即微污垢)的同时迅速清除它们的粘附面，从而防止污垢堆积(即大污垢)。频率被扫频，网络的不同部分依次激励扫描声纳节点通过100%的船体。这项计划将100%去除船体和螺旋桨表面的生物膜，连续波的开启/关闭时间最短，即最小时间平均功率。周期性地，脉冲波将被激发，以检测由于去除不完善的生物膜而引起的意外宏观污染，然后通过暂时增加连续的开/关时间，然后恢复正常操作来消除。亚空化水平的超声力场可以防止生物污垢的初始形成，进一步降低平均功率消耗，这一可能性有待研究。

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.