Laser cutting was performed using a 6-kW fiber laser with two different nozzle configurations to extend the permissible cutting thickness of steel blocks in a water environment. The first nozzle configuration involved a single minimum length nozzle (MLN) operating at an upstream gas gauge pressure of 15 bar; the second configuration consisted of a truncated aerospike nozzle coupled with an MLN. These configurations were designed to form a core air-filled cavity with the submerged jet to have denser and more lengthened characteristics for extending the possible transmission distance of the high-power laser beam, which is vulnerable to water absorption. Before underwater cutting, we performed a Schlieren visualization measurement of the gas jet’s flow behavior as it was discharged from the single and dual nozzles in the ambient air, after which, the stainless steel blocks were laser-cut underwater using both nozzle configurations. The thickness of the selected steel blocks varied from 60 to 80 mm according to the capabilities of the nozzles used to form the air cavity.

使用具有两种不同喷嘴配置的6 kW光纤激光器进行激光切割，以扩展水环境中钢块的允许切割厚度。第一种喷嘴配置包括单个最小长度喷嘴（MLN），其在15 bar的上游气压下工作；第二种配置包括与MLN相连的截顶式气嘴。这些配置旨在与浸没式射流一起形成一个充满空气的芯腔，从而具有更致密和更长的特性，从而可以扩展高功率激光束的可能的传输距离，从而容易吸收水。在水下切割之前，我们对气体喷射流从周围空气中的单喷嘴和双喷嘴排放时的流动行为进行了Schlieren可视化测量，然后，使用两种喷嘴配置在水下对不锈钢块进行激光切割。根据用于形成空气腔的喷嘴的能力，所选钢块的厚度从60毫米到80毫米不等。