Investigation into the effects of petalling on coefficient of discharge during compartment flooding

Ships or risers, among many other marine structures, incur damage even with the best precautions. Whilst these damages can be catastrophic they often lead to scenarios whereby the damaged structure is ailing but not failed. In these scenarios the structure will flood and it is vital that the rate of flooding can be estimated, from a limited knowledge of the damage, so that safety and the environment can be best considered and an economical and effective recovery or repair of the vessel occurs. In an effort to improve the modelling and hence improve the advice available, research has been performed into how petalling, folding of the structure at the edge of the damage, effects the flooding of the structure. Experiments have been conducted on petalled structures and the results are compared to the coefficient of discharge for flat edged damages. The results show that petalling makes a substantial difference to the coefficient of discharge of the orifice flow which is largely dependent on the petalling angle which can both reduce or increase the flow rate dependent on the orientation. However, this difference can be predicted if the type of petalling is known.