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Research on hydrodynamic properties of annular cavitator with water injection

100%

Jiang Z. , Xiang M. , Lin M. , Zhang W. , Zhang S.

Polish Maritime Research

2012

tom 19

nr 4

Annular cavitator with water injection is one of the key parts of the long-range supercavitating vehicle powered by water ramjet. In this paper, hydrodynamic properties of annular cavitator are studied numerically. The standard k ~ ε turbulence model is coupled with the Reynolds Averaged Navier-Stokes (RANS) equations to model the natural supercavitation process. The multiphase flow is considered as a mixture of varying density and modeled by the mass exchange equations. To fully understand this process, numerical simulations were performed for different annular cavitators. Computational Fluid Dynamics (CFD) results, including the pressure distribution and forces acting on the cavitator surface, mass flow and pressure loss of water injection, various supercavity sizes, were obtained and analyzed. The pressure distribution on the cavitator surface was significantly changed which resulted in 4 ~ 6% increase of the total drag of the vehicle. The results show that the mass flow and velocity of the injection water is mainly dependent on the tube size, while the total pressure loss of the water injection is mostly related to the outlet pressure. Supercavity generated by annular cavitator is smaller than that of the discal one. Based on the correlation analysis of the supercavity size and other factors, it could be concluded that the contraction of the cavity size is mainly caused by the diffluent mass flow of the water injection

The variations of concentrations, profilies and possible sources of metals and polycyclic aromatic hydrocarbons in PM10 from Lanzhou, China

72%

Yu Y. , Wang Q. , Li L. , Sun P. , Zhang Y. , Lin H. , Chen J. , Lin B. , Xiang M.

Polish Journal of Environmental Studies

2016

tom 25

nr 3

Metals and polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in airborne particulate matter. In order to better understand the concentrations and origins of metals and PAHs bound to particulate matter in Lanzhou city in northwest China, six metals (Cu, Zn, Ni, Pb, Cd, and Cr) and 16 selected PAHs in 108 part iculate matter samples were quantified by inductively coupled plasma/mass spectrometry (ICP-MS) and gas chromatography/mass spectrometry. Results demonstrated that metals and PAHs in the ambient air of Lanzhou city showed regional and seasonal trends, and their concentrations were higher than those in several other Asian and European cities. The high molecular weight PAHs in winter were higher than in summer in both Xigu District and Yuzhong town. The principle components analysis (PCA) method was applied to analyze the sources of metals bound to particulate matters (PM2.5, PM10, TSP) and PAHs bound to PM10, and results showed that vehicle emissions, coal combustion, and oil combustion were probably the main sources of metal and PAHs in Lanzhou PM.