The hazard of highly combustible marine oil leakage greatly increases fishing vessel operation risks. This research integrates an experiment to explore the coupling mechanism of a typical heated surface of an engine room as a source to ignite marine oil. A numerical model is established that depicts the dynamic process of and variations in the combined effects regarding multiple factors of oil ignition under actual experiment. The leaked marine oil is ignited with a heated surface, relevant models are applied to reproduce the results, and the influences of specific parameters of a fishing vessel’s engine room are analyzed. The results indicate that the leaked oil boils violently on the heated surface, and a vapor film forms on the oil surface. Increased heated-surface temperatures lead to a significant difference in the initial ignition occurrences of marine oil, and the distance between the ignition height and oil is closely related to the engine room environment. The ignition probability of marine oil shows a gradually increasing trend with elevated heated-surface temperatures. The ignition height presents a downward trend with the increase in the heated-surface temperature, while the engine room’s humidity in air inhibits the upward transfer of heat; however, the degree of inhibition is limited accordingly. The results evidence that this comparative work can be an effective approach to reveal the impacts of marine oil, heat source, ventilation velocity, and humidity on initial ignition characteristics. Additionally, this work provides a basis for setting up emergency planning with appropriate monitoring equipment and further preventing vessel fires due to oil–thermal ignition.

Ship resistance has a very important value in the determination of ship power and the design of emission standards. In this paper, a ship resistance model with different displacement, speed, and attachment under the condition of a fixed scale ratio is tested by means of experimental research, which is used to analyze the change law of ship resistance under the condition of a single factor. The coupling effects of multiple factors on the actual ship power are studied after the establishment of a mathematical relationship between the actual ship power and resistance on the basis of the response surface method. The research results show that: (1) there is an obvious positive correlation between ship resistance and speed, which matches the change law of the exponential equation. Compared with ship appendages, displacement and speed have the greatest influence on resistance. (2) According to the correlation analysis, the maximum correlation coefficient between ship speed/resistance and power is 0.99, and the correlation coefficients between displacement/resistance and power are 0.93 and 0.88, respectively. However, the correlation coefficients between ship appendages and resistance and power are only 0.23 and 0.14, respectively. (3) The actual ship power and speed, displacement, and appendages form a quadratic polynomial relationship. The multi-factor interaction analysis results show that speed and displacement have the greatest influence on the actual ship power. The research results have a certain guiding significance for ship design.

Harmful algal blooms (HABs) are one of the major hazards in aquaculture activities, and modified clay is an effective approach for HAB prevention and control. Based on the DEM-VOF coupled model, this study investigates the synergistic coupling effects of factors such as particle density, particle size, stirring speed, and mixing time on the sedimentation and stirring efficiency of clay particles, analyzes the evolution characteristics of the multiphase flow field structure inside the stirring equipment, and evaluates the mixing effect of modified clay under different key parameter conditions. The results show that particle density is inversely proportional to mixing uniformity, with the lowest relative standard deviation (RSD) value obtained at a density of 1000 kg/m ³ . Reducing particle size can improve mixing efficiency, and the minimum RSD value is observed at a particle size of 3 mm. Stirring speed is significantly positively correlated with mixing performance, and the particle distribution is most uniform at 200 r/min. The mixing process reaches dynamic equilibrium at 25 seconds, and further extending the mixing time thereafter has limited improvement on performance. The synergistic coupling of 3 mm particle size and 200 r/min stirring speed (with 1000 kg/m ³ particle density and 25 s mixing time) achieves the best mixing effect, reducing RSD by 26.5% compared to the baseline condition. The research results provide a reference for the optimization of mixing parameters of modified clay mixing and spraying devices, and offer a theoretical basis for enhancing the operational efficiency of aquaculture HAB control equipment.