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In the present work, we focus on computational investigations of the Reynolds number effect and the wall heat transfer on the performance of axial compressor during its miniaturization. The NASA stage 35 compressor is selected as the configuration in this study and computational fluid dynamics (CFD) is used to carry out the miniaturization process and simulations. We perform parameter studies on the effect of Reynolds number and wall thermal conditions. Our results indicate a decrease of efficiency, if the compressor is miniaturized based on its original geometry due to the increase of viscous effects. The increased heat transfer through wall has only a small effect and will actually benefit compressor performance based on our study.

COVID-19 is a serious respiratory disease caused by a devastating coronavirus family (2019-nCoV) that has become a global epidemic. It is an infectious virus transmitted by inhalation or contact with the droplet core produced by infected people when they sneeze, cough, and speak. SARS-COV-2 transmission in the air is possible even in a confined space near the infected person. This study examines air conditioners’ effect on the mixed virus and droplets with aerosol disinfectant and gets throughout the elevator to detect the SARS-COV-2, which helps protect passengers’ lives. This study uses fluent 2019R3 software to simulate the virus transmission to model the transient flows numerically. The analysis found that the ventilation system’s turbulent fields can be an effective method of protecting the space from being saturated by the coronavirus.

Air-intake filter of the ventilation system on offshore platform plays an important role in providing sufficient and clean air and is normally composed of the inertial stage and the multi-layer gauze stage. In this article, numerical simulation and experimental research were carried on to study the flow field characteristics of the air-intake filter. Flow in the inertial stage was regarded as a 2D case, and the multi-layer gauze stage was simplified to an orthogonal array type. With FLUENT code, the quadratic polynomial of the resistance with velocity, the permeability α and the pressure jump coefficient C₂ of the composite stages were obtained on the basis of certain simplifications. Accordingly, one source term was added into the momentum equation, and the flowing characteristics of the filter compounding the inertial stage and the gauze stage were computed based on the porous medium model. The simulating results of the total pressure loss are validated by the designed wind-tunnel experiment satisfactorily. This method has much reference value on the design and optimization of the air-intake filter on offshore platforms and other occasions.

In this paper, to investigate a compound casting process for creating Al coating layer for Mg alloy, a computational fluid dynamics (CFD) model is developed using the VOF method to simulate the molten Mg drop impact on the Al substrate at solid state. A spreading factor, which is the ratio to the varied diameter of the Mg droplet after impacting on the Al substrate and its initial diameter before the impact, is used to describe and measure the impact process generated by the Mg drop, which could be divided into several steps: spreading, retracting and oscillating, and equilibrium as final step. Some key parameters are investigated via parametric studies: impact velocities, initial diameters of drop, the temperature of the Al substrate, which have important influences on the quality of compound casting products. The spread diameter of the Mg drop increases when the impact velocity and initial diameter of drop increase. While the impact velocities and initial diameters of the drop are larger than critical values, the liquefied Mg may partially have bubbles. The higher the temperature of the Al substrate is, the larger the spread diameters could be obtained, though oscillating and equilibrium steps take more time to finish in the CFD simulations developed.

OpenFOAM is an object-oriented C++ library of classes and routines of use for writing CFD codes. It has a set of basic features similar to any commercial CFD solver, such as turbulence models and discretization schemes. The paper presents the numerical studies of sediment wear in a centrifugal pump impeller using OpenFOAM code, which is an Open Source CFD Package. The 3-D turbulent particulate-liquid two-phase flow equations are employed in this study. Hashish erosion model was implemented in this code. The sand volume fraction distribution, sand erosion rate distribution, wall shear strain rate distribution and wall stress distribution in the impeller were analyzed. Simulation results have shown that the main sediment wear of impeller is at the suction side of the inlet and the pressure side of the outlet.