Esam Jassim

Computational Fluid Dynamics Study for Flow of Natural Gas through High-pressure Supersonic Nozzles: Part 1. Real Gas Effects and Shockwave

Abstract The computational fluid dynamics technique was used to study the behavior of high-pressure natural gas in supersonic nozzles. Although many applications of gas flow produce insignificant errors when the gas is assumed ideal, our results indicate significant variation of gas properties. This article illustrates natural gas behavior when it is considered to be real and how erroneous the properties may become when the gas is assumed to be ideal. The article also presents the influences of properties related to the flow of natural gas through supersonic nozzles. Using a quite accurate equation of state model, real gas effects are studied and compared with the perfect gas case. The results show a significant variation in gas properties estimation. Location of shockwave is also analyzed. The comparison of results for two gases (methane and nitrogen) indicated that shockwave position can significantly change when the gas is considered as real rather than perfect.

Computational Fluid Dynamics Study for Flow of Natural Gas through High-pressure Supersonic Nozzles: Part 2. Nozzle Geometry and Vorticity

Abstract The computational fluid dynamics technique is used to study the behavior of high-pressure natural gas when it flows through nozzles with supersonic velocities. Effect of nozzle geometry is discussed by inserting a constant area channel between the convergent and divergent parts of the system. Various conduit lengths are analyzed to show how the minimum temperature could be influenced by the geometry of the nozzle. The results also show that changing channel length can affect the position of shockwave. The results for the effect of vorticity on the performance of the nozzles show that, although losses in pressure increase due to inlet swirl flow, vorticity increases very sharply in the vicinity of the shock. It could be concluded that the region just before the shock spot is the main region where fine particles can be separated because of the large vorticity strength. Shock with reasonable strength may be favored in practical applications where fine particles separation is desired.

Applications of CFD in Natural Gas Processing and Transportation

In this chapter, two examples of CFD applications in natural gas processing and transportation are presented. A commercial software package (Fluent) was used in these studies. The purpose of the studies is brie fly discussed, the methodology outlined and boundary conditions and problem specifications are concisely described for each case. The results of investigation s and comparisons with experimental tests and literature data are presented to demonstrate how CFD can be applied to practical situations.

VISUALIZATION AND MEASUREMENTS OF BUBBLY TWO-PHASE FLOW STRUCTURE USING PARTICLE IMAGING VELOCIMETRY (PIV)

The conducted clinical and instrumental study revealed that the aggregate group of the patients with chronic diseases of throat differs by increased frequency of isolated and combined disorders of gastrointestinal tract. If a patient has such symptoms as hoarseness, tickling, scratching, burning, feeling of dryness in throat, frequent variant of gastro-intestinal tract disorders is gastroesophageal reflux disease with pharyngolaryneal reflux. There are such severe pathologies of throat as pachydermia of vocal cords and nodules of vocal cords among more frequently met disorders at gastro-intestinal tract diseases. High probability of accompanied pathology of throat in the form of pachydermia and nodules of vocal cords at patients with gastro-intestinal tract disorders stipulates for the necessity of conducting fibrorhynolaryngoscopy in combination with fibergastroscopy.Study presents short overview of drug situation’s indicators during the first, or heroin decade of drugs, and then during the second, soft and synthetic drugs decade of drugs in Slovakia. Then the results of series of nation-wide school surveys, mapping development of licit and illicit drugs use among children and youth during nineties are outlined. The results indicated constant growth of licit and illicit drugs consumption among primary school pupils, and secondary school students until the fourth wave of nation-wide school surveys in the years 2006 – 2007. However, the next wave after four years has detected profound change in the expected pattern of further growth in the case of illicit drugs. Instead of this decline of use or at least stabilization occurred among Slovak youth. At the same time we have found growth of use in the case of licit drugs – alcohol and tobacco, more profoundly among girls. Also the use of new synthetic drugs among young people was revealed via traditional school survey.