RAPID: Assessing flow rate of Macondo oil spill

在这场灾难中，石油的流量问题已经成为一个中心问题，主要有两个原因：(1)指挥应对需要知道石油表面的位置和海岸，以及(2)确定可以使用哪些技术来密封油井，关键是要知道流量。5月20日，艾伦上将成立了流量技术小组(FRTG)，以解决石油流量的问题。韦利教授被任命为这个团队的成员。在对各种流动方案进行了一个月的计算和审议后，FRTG确定最有可能的石油流量仅为3.5万至6万桶/天，不包括甲烷或其他气态碳氢化合物。FRTG主要使用遥控车辆(ROV)拍摄的视频，因为几乎没有其他仪器可用。通过不同的方法对视频进行分析，以估计石油的流量。FRTG的一些成员使用粒子图像测速仪(PIV)代码来跟踪喷油射流外表面的相干结构，以确定其速度。根据喷气式飞机的表面速度，必须估计喷气式飞机的平均速度。这一步存在相当大的不确定性。虽然喷流文献跨越了至少100年，但这里的特殊场景是独一无二的：加热的、不相容的、不透明的、不同性质的两相流喷射到无限储集层中。文献提供了一些关于外部结构速度和射流平均速度之间的关系的指导，但这种关系仍然存在，因为流量估计的上下限之间的范围几乎是2倍。这里提出的是一套实验室实验，将尽可能接近地复制石油流入海水的实际情况。将对流动进行录像，并以类似于FRTG程序的方式进行分析。因为实验是在实验室中进行的，所以可以知道油射流的平均流量，并可以很好地了解外表面特征速度和平均射流速度之间的关系。这项活动的智力优势是双重的。首先，将为溢油防御性分析提供新的方法提供坚实的理论基础。第二，将探索特定类型的喷气式飞机的物理。这一活动的广泛影响是相当大的。目前估计的35,000至60,000桶/天的流量范围的接近2倍的范围过大，在很大程度上是由于外部可跟踪的相干结构速度与喷流平均速度之间的不确定关系。这项工作的目标是大幅缩小这一范围。对溢油流量有更准确的了解，对于在正在发生的灾难和未来肯定会发生的灾难中指导溢油反应至关重要。

The issue of the flow rate of oil during this disaster has become a central issue for primarily two reasons: (1) directing the response requires knowing where the oil where surface and which shores it wash up on and (2) determining which technologies can be used to seal the well depends critically on knowing the flow rate. On May 20, Admiral Allen created the Flow Rate Technical Group (FRTG) to address the question of oil flow rate. Prof. Wereley was appointed a member of this team. After a month of calculations and deliberations over various flow scenarios, the FRTG determined that the most likely flow rate of oil was 35,000 to 60,000 bbl/day of oil only, not including methane or other gaseous hydrocarbons. The FRTG primarily used videos shot by remote operated vehicles (ROVs) because very little other instrumentation was available. The videos were analyzed by various methods to estimate the flow rate of the oil. A number of members of the FRTG used particle image velocimetry (PIV) codes to track the coherent structures at the outer surface of the oil jet to determine its speed. From the surface speed of the jet, the average speed of the jet had to be estimated. There is considerable uncertainty in this step. While the body of jet flow literature spans at least 100 years, the particular scenario here is unique: two phase flow of a heated, immiscible, opaque flow of different properties ejecting into an unbounded reservoir. The literature provided some guidance on what the relationship was between the outer structure speed and the average speed of the jet but this relationship remains the reason that the range between the upper and lower bounds of the flow rate estimate represents nearly a factor of 2. What is proposed here is a set of laboratory experiments that would as closely as possible replicate the actual situation of oil flowing into sea water. Video would be taken of the flows and analyzed in a manner similar to the FRTG's procedure. Because the experiments are conducted in a lab, the average flow rate of the oil jet will be known and a very good idea of the relationship between the outer surface feature speed and the average jet speed can be found.The intellectual merit of this activity is two-fold. First, a new method for stand-off analysis of oil spills will be given a solid theoretical base. Second, the physics of a specific class of jets will be explored. The broader impacts of this activity are considerable. The nearly factor of 2 range on the current flow rate estimate of 35,000 to 60,000 bbl/day are excessively large and due, in large part, to the uncertain relationship between the outer trackable, coherent structure speed and the average speed of the jet. The goal of the work here is to considerably narrow this range. Having a more precise knowledge of the oil spill flow rate is critical to directing the oil spill response both in the on-going disaster and in future disaster which are certain to happen.