Computational fluid dynamics (CFD) numerical simulation is adopted to analyze the drag reduction ability of triangular riblet on tube internal flow. The resistance characteristic of smooth tube and tube covered with triangular riblet surface are compared, and the near wall flow structure over smooth surface and riblet surface are investigated. Based on the simulation analysis, the drag reduction mechanism of riblet surface is studied. Results show that the characteristic dimension of riblet section, i.e., height (h) and width (w) are main factors affecting drag reduction, suggesting that the riblet structure can be optimized according to the actual application condition.

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The waste heat emissions of thermal discharge from floating nuclear power plants may have a negative thermal effect on the environment. Study on the dilution and diffusion of cooling water plays an important role in thermal pollution prevention. The cooling water discharge process can be condensed into the thermal jet in cross flow. According to the theory of computational fluid dynamics, the mathematical model of round horizontal thermal jets in cross flow is established. The 3D numerical simulation of thermal jets based on finite volume method is achieved by using the Realizable k-ε turbulence model and the Semi-implicit method for pressure linked equations, and the three-dimensional trajectory of thermal jet are obtained. The rationality of analysis method is approved by comparing calculation value with experimental value. The temperature distributions in thermal jets are studied through the numerical experiments conducted under different cross-flow velocity and different emission angle. As a result, the impacts of these conditions on thermal pollution area are found, and the theoretic bases are provided for the design of the cooling water discharge pipe.

In order to obtain the drag coefficient in accuracy, it needs to correct the model’s buoyancy drag coefficient in the high-speed wind tunnel test. However, there are several methods on calculating the buoyancy drag coefficient, each will generate a result differently. Three types of methods are studied in this paper, the formulas are derived, the buoyancy drag coefficients are calculated, and the results are compared in the end. It shows that the most exact method is the one based on pressure fitting function, it’s suitable for correcting the model’s drag coefficient with high accuracy requirement.

A basic model with both property of thermodynamic and heat transfer is obtained by simplifying the prime process of ship Steam Power System (SPS), which is converted into endoreversible Carnot Cycle by the introduction of mean temperature in the cycle process. The design parameters is analyzed and optimized in the view point of finite time thermodynamics (FTT) and entropy generation minimization. Results show that, the temperature ratio (α) and the heat transfer parameter ratio (β) of heat source and heat sink are two important influence factors of cycle system performance, and the increase of α and decrease of β will redound to the reduction of irreversible loss and enhancement of power output.