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⎯ ⎯ cavitation is defined as a phenomenon or action of the traveling bubbles that pass through the hydrofoil in which the reduction of pressure below the liquid's vapor pressure leads to the formation of small vapor bubbles (or cavities) caused by the dynamic pressure of the propeller blades. It caused some effects on the propeller of the ship i.e. it can greatly reduce a ship's propelling efficiency, damaged propeller material or blade erosion, vibration, and disturbance noises. Cavitation can be minimized by proper attention regarding the design of the propellers and variation of propeller variables parameters. For that reason, this research conducts a cavitation analysis on the Kaplan-Series of the CPP by varying P/Db=0.4, P/Db=0.6, and P/Db=0.8; also the rotational speed of the propeller (nProp) i.e. 125 rpm, 175 rpm and, 225 rpm. The numerical analysis was made based on the Computational Fluid Dynamic Method (CFD) to calculate the pressure ratio (ΔP) and percentages of the cavitation area (Rs) due to a configuration of the propellers parameter. The simulation consists of the 3 steps; pre-processor, solver manager, and post-processor. The result shows that the value of the pressure ratio increased significantly at the higher P/Db and nProp. Also, the variation of P/Db and nProp has a significant effect on the development of Rs (%) at the higher P/Db and nProp.Keywords⎯cavitation, computational fluid dynamic, CPP, kaplan-series propeller, nProp, pitch ratio.

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Natural gas/diesel dual-fuel engine is known as a solution for shipping industries to simultaneous reduces NOx and PM emissions nowadays. Unfortunately, high HC emissions are produced, especially at low loads conditions. However, there are two possibilities for the source of HC emissions from the engine, namely during the combustion process and during the scavenging process. This study evaluates the methane emissions (part of HC emissions) concentration during the scavenging process. Cold flow engine simulations are evaluated and validated to this study at low load condition using natural gas injection at intake port during valve overlap. Moreover, several natural gas injection timings are conducted to observe the effect on the methane emissions concentrations at exhaust port after the exhaust valve closed. The natural gas penetration is nearly after the intake valve closed (IVC) thus the natural gas enters the combustion chamber at the next intake cycle. It observed that the scavenging process contributes to the methane emissions formation on natural gas/diesel dual-fuel engine using intake port natural gas penetration after IVC. Besides, the concentration of methane emissions during the scavenging process has very low contribution than the combustion process. It is possibly a variation of the methane emissions concentration in the other valve lift profile and natural gas injection strategies. Thus, it recommends to widely observing how significant the methane emissions generated during the scavenging process on the other engines with those variations.