This paper addresses a design optimization of a gas turbine (GT) for marine applications. A gain-scheduling method incorporating a meta-heuristic optimization is proposed to optimize a thermodynamics-based model of a small GT engine. A comprehensive control system consisting of a proportional integral (PI) controller with additional proportional gains, gain scheduling, and a min-max controller is developed. The modeling of gains as a function of plant variables is presented. Meta-heuristic optimizations, namely a genetic algorithm (GA) and a whale optimization algorithm (WOA), are applied to optimize the designed control system. The results show that the WOA has better performance than that of the GA, where the WOA exhibits the minimum fitness value. Compared to the unoptimized gain, the time to reach the target of the power lever angle is significantly reduced. Optimal gain scheduling shows a stable response compared with a fixed gain, which can have oscillation effects as a controller responds. An effect of using bioethanol as a fuel has been observed. It shows that for the same input parameters of the GT dynamics model, the fuel flow increases significantly, as compared with diesel fuel, because of its low bioethanol heating value. Thus, a significant increase occurs only at the gain that depends on the fuel flow.

We investigate the interfacial dynamics of two immiscible fluids flowing within a two-dimensional microchannel with structured wall roughness through numerical simulations. The simulations are performed using a finite-volume approach combined with the volume-of-fluid method to capture the fluid interface. Wall roughness is introduced on one wall of a straight channel in the form of an obstacle array. Three different obstacle shapes are considered: rectangular, triangular, and semi-elliptical. The effects of geometric parameters, including the spacing-to-width ratio (s/d) and height-to-width ratio (h/d), intrinsic contact angle (θC), viscosity ratio, and capillary number (Ca), are examined. The results show that roughness shape strongly influences interfacial behavior. The rectangular shape produces the largest interfacial deformation and promotes greater water entrapment, whereas the triangular shape results in a more stable interface. Reducing s/d increases water trapping and slightly accelerates interface movement, whereas increasing h/d produces a more pronounced influence on the flow. Changes in θC alter the interface curvature and are associated with higher apparent contact angles and more frequent water entrapment within the cavities. The onset of partial water trapping occurs at a local capillary number of approximately 1.1×10−4 for triangular and rectangular elements, whereas semi-elliptical profiles require a nearly fourfold higher threshold. For capillary numbers below 10−3, the static contact angle formulation remains physically valid because deviations of the dynamic contact line are minimal.