Papers by Keyword: Turbulent Mixing

Abstract: Raja Ampat Sea has a complex geometry and passed by Indonesian Throughflow (ITF) causing a very dynamic water condition, that condition also amplified by turbulent mixing. To gain better understanding of process and extent of turbulent mixing in Raja Ampat Sea, this research calculate Brunt-Vaisala frequency, Richardson number, turbulent kinetic energy dissipation rate and vertical diffusivity coefficient. The data obtained from Expedition Widya Nusantara (EWIN) by P2O-LIPI in the territorial of Raja Ampat Sea on 14-24 November 2007, by using 12 out of 33 observation stations. From this research, it is known that in 0-40 m (mixed layer) and 250-400 m (deep layer) have Richardson number (R_i) less than 0.25 and high vertical diffusivity coefficient (K_v), It proves a strong turbulent mixing occurs at those depth. Furthermore, Raja Ampat Sea has strong turbulent mixing with average value of turbulent kinetic energy is 2.64 WKg^-1and vertical diffusivity coefficient is 1.65x10^-3 m²s.

Abstract: The model of phase structure formation of the surface during electron beat with modifying particles is described. The role of particles mixing in the formation of the surface layer is investigated numerically. It is shown that melt turbulent mixing leads to more fast particles dissolution in the melting pool and to more homogeneous composition in comparison with the model without mixing.

Abstract: Turbulence mixing in T-junctions filled with porous metal materials is numerical investigated using Large-eddy simulation turbulence model. Three cases of porous metal materials, made of three sintered metal spheres with different thermal conductivities (387.6 W/m۟۬•K for copper, 202.4 W/m۟۬•K for aluminum and 16.3 W/m۟۬•K for steel), are predicted. Compared the results of three cases, a higher thermal conductivity can also contribute more greatly to heat transfer enhancement. In T-junctions filled with porous metal materials, thermal conductivity is weakened considerably by the turbulence mixing of hot and cold fluid. The temperature fluctuation are no obvious different.

Abstract: In order to investigate the multipoint ignition process and the combustion stability controlling mechanism of the bulk-loaded liquid propellant gun, the cylindrical stepped-wall observation chambers and cylindrical observation chambers are designed. The expansion process and interaction of high-speed twin combustion-gas jets in liquid are studied by high speed photographic system. The influence of chamber structure, nozzle diameter, dual-orifice interval, jet pressure on twin gas jets expansion process has been discussed.

Abstract: Micro- and Macro-mixing models were built and numerical investigation of turbulent mixing in ejectors was carried out. Mixture fraction and its variance presented by Fox were remodeled to demonstrate micro- and macro-mixing performance. The length needed to reach 98% micro- and macro-mixing were founded is functions of u_j/u_m and D/d. The mathematical scale-up models were presented based on the simulation results using least square method for micro- and macro-mixing and five different cases were used to validate the models. The results showed that macro-mixing scale-up model agreed well with CFD simulations but the micro-mixing scale-up model had a less precision compared with that of macro-mixing model. This because that the mechanism of micro-mixing process is very complexity but the CFD models we used in this work are fairy simple.