The hydrodynamic pressure field and wake generated by an advancing underwater vehicle are used as key factors for its detection identification. In this paper, a numerical method is established based on the Reynolds-averaged Navier–Stokes equation. Following grid convergence verification seven kinds of grids, differences between investigated using gridding turbulence model. Subsequently, validation basis, characteristics correlation at different water depths studied, showing that SST model...

A thermodynamic analysis of the R404A refrigeration system with an internal heat exchanger using R744 as a secondary refrigerant is presented in this paper to optimize design for operating parameters system. The main results are summarized follows: COP increases increasing subcooling and superheating degree R404A, compression efficiency cycle evaporating temperature decreasing difference cascade condensing cycle. mass flow ratio decreases cycle,

In this paper, the heat transfer coefficient and pump consumption power of indirect refrigeration system using <TEX>$CO_2$</TEX> as a secondary refrigerant were investigated experimentally. First, from comparison powers existing brines(EG, PG, EA etc.) refrigerants at same experimental conditions, PG show highest lowest power, respectively. Second, <TEX>$CaCl_2$</TEX> is highest, but among other refrigerants. From above results, it confirmed that has excellent characteristics when comparing...

A ship advancing in restricted waters may cause a change the surrounding velocity field, which turn results hydrodynamic pressure field according to variations speed. Accurate prediction of fields is therefore essential and important military engineering fields. Based on potential flow theory thin-ship assumption, dividing complex with varying depths into inner outer domains constant depths, mathematical modeling method developed carried out for analyzing solving partial differential...

In this paper, the performance characteristics of R404 indirect refrigeration system using R744 as a secondary refrigerant were investigated experimentally to obtain optimum design data for system. First, constant experimental conditions, COP R404A refrigerants decreases with respect increases in condensation temperature and difference cooler. And, slightly decreasing mass flowrate R744.

This paper presents the comparison of heat transfer and pressure drop various secondary refrigerants (single-phase two-phase) in indirect refrigeration system. The main results were summarized as follows: In case transfer, it is useful to use low evaporating temperature region coefficient single-phase larger than two-phase refrigerants. drop, high smaller refrigerant. Also, <TEX>$CO_2$</TEX> best because among smallest.

The RANS equation and BSL k- ω turbulence model are employed to solve the internal wave generated by a moving submerged body in continuously stratified fluid, utilizing unsteady methods. Consequently, relationship between patterns diving depth as well maximum crest trough height with respect can be determined.

Debris flow is one of the life threatening natural hazards frequently occurring during heavy rain or typhoon. It generally defined as a mixture solid particles various sizes and water. Due to high uncertainty inherited in phenomena, problem has not been well investigated still remains with many unanswered issues. Recent experimental studies understand debris have revealed some its nonlinear behavior viscosity soil-moisture content; however, computational analysis early stage. This paper...

This paper presents the computational analysis of debris flow using multi-phase modeling and resulting impact force on structure. The mixture soil water was modeled as slurry phase for various content controlled by volume concentration each material. Unsteady solved incompressible fluid in 3D domain (VOF) method introduced to trace boundary between ambient air. Due shear thinning characteristics slurry, nonlinear viscosity model implemented. In order verify present method, numerical...

A high accuracy non-contact laser measuring system about displacement was developed to obtain the surface deformation of ice-like material. speed measurement and positioning established for moving air cushion load. The mechanical properties material pressure distribution load were measured. To different speed, a series experiments carried out in towing channel which depth water variable. maximum can be caused when moves at critical prediction method presented, good agreement exists between...