Complex flow physics & active plasma flow control in convoluted ducts

Convoluted, s-shaped ducts form an integral part of many subsystems in engineering applications and specifically the aviation industry. They are used, for example, as inlet ducts for fuselage embedded jet engines and as connector pipes between high and low pressure turbine or compressor stages. With a strong curvature and a diffusive nature, the geometry acts on the through-flow making it prone to separate and experience significant cross-stream pressure gradients. The geometry and resulting flow phenomena lead to a non-uniform and highly unsteady flow field in the duct aft the inflection point. Those effects are detrimental to the overall performance of the convoluted duct, reducing the pressure recovery and increasing the distortion parameters. S-shaped ducts have been studied by a large number of researchers for many years. Traditionally, many studies rely on steady state simulations and time averaged experimental data to characterise the flow in convoluted ducts and analyse their performance. However, more recent findings point to the need of transient data to fully understand the dynamic nature of the through-flow and discuss the complex flow physics. This is something that is lacking from many studies reported in the current literature. This is addressed with computational fluid dynamics (CFD) studies of the through-flow in the s-duct using the open source tool OpenFOAM. First low fidelity, steady state simulations are set up before higher fidelity, transient delayed detached eddy simulations (DDES) are conducted. Baseline s-duct through-flow computations are validated against experimental data from literature with very good agreement of pressure recovery values, wall static pressure contours, and flow structures. CFD data is next post processed with statistical and modal decomposition methods. Coherent structures and phase information are obtained from the proper orthogonal decomposition (POD) and the dynamic mode decomposition (DMD) methods. Modal decomposition analysis of DDES data confirms the existance of the horizontal shifing mode. Contrary to previous findings, the presence of a second vertical shifting mode is observed from DDES data. Occurance rates and phase information are determined from the DMD analysis. The recent surge of interest in plasma actuators is clearly illustrated by the high research output that has been reported in literature. Dielectric barrier discharge (DBD) plasma actuators have been studied and successfully applied to control external aerodynamics on aerofoils and bluff bodies. However, successful flow control in convoluted ducts has not been reported with this technology for realistic Reynolds numbers. The DBD plasma characterisation is conducted on two types of actuators: alternating current (ac) and nanosecond (ns) DBD plasma actuators. The Schlieren imaging technique is used with ns-DBD plasmas to record density changes and establish the shock front strength and propagation speed with changing ambient pressure. Higher ambient pressures result in stronger shock waves; this has been observed irrespective of the actuator thickness. This might be explained with fewer air molecules to ionize at lower ambient pressures and hence a lower temperature from the exothermal recombination reactions. For ac-DBD actuators, thinner dielectric materials outperformed thicker ones in terms of ionisation strength with constant voltage input. The smallest dielectric constant of the materials tested resulted in higher induced velocities. Using particle image velocimetry (PIV), a high gradient of velocity reduction with streamwise distance was recorded in the plasma jet. This is significant, as it shows plasma actuators have mostly localised effects. Experimental campaigns are set up such that the DBD experiments are coherent studies in their own right. However, the main purpose of plasma experiments in the context of this thesis is to collect data to validate numerical plasma models. Those phenomenological plasma models are subsequently used for numerical flow control studies on the s-shaped duct. Phenomenological plasma models match the experimental data well when tuned. However, the flow control studies did not show a performance improvement in the convoluted duct

Commonwealth of Independent States aerospace science and technology, 1992: A bibliography with indexes

This bibliography contains 1237 annotated references to reports and journal articles of Commonwealth of Independent States (CIS) intellectual origin entered into the NASA Scientific and Technical Information System during 1992. Representative subject areas include the following: aeronautics, astronautics, chemistry and materials, engineering, geosciences, life sciences, mathematical and computer sciences, physics, social sciences, and space sciences

Energy: A continuing bibliography with indexes, issue 31

This bibliography lists 1111 reports, articles, and other documents introduced into the NASA scientific and technical information system from July 1, 1981 through September 30, 1981

12th EASN International Conference on "Innovation in Aviation & Space for opening New Horizons"

Epoxy resins show a combination of thermal stability, good mechanical performance, and durability, which make these materials suitable for many applications in the Aerospace industry. Different types of curing agents can be utilized for curing epoxy systems. The use of aliphatic amines as curing agent is preferable over the toxic aromatic ones, though their incorporation increases the flammability of the resin. Recently, we have developed different hybrid strategies, where the sol-gel technique has been exploited in combination with two DOPO-based flame retardants and other synergists or the use of humic acid and ammonium polyphosphate to achieve non-dripping V-0 classification in UL 94 vertical flame spread tests, with low phosphorous loadings (e.g., 1-2 wt%). These strategies improved the flame retardancy of the epoxy matrix, without any detrimental impact on the mechanical and thermal properties of the composites. Finally, the formation of a hybrid silica-epoxy network accounted for the establishment of tailored interphases, due to a better dispersion of more polar additives in the hydrophobic resin

Proceedings of the Scientific-Practical Conference "Research and Development - 2016"

talent management; sensor arrays; automatic speech recognition; dry separation technology; oil production; oil waste; laser technolog

Programme and The Book of Abstracts / Twentieth Annual Conference YUCOMAT 2018, Herceg Novi, September 3-7, 2018

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)

Gas Discharge Plasmas and Their Applications (GDP 2019): 14th International Conference, September 15–21, 2019, Tomsk, Russia: abstracts

The book contains abstarcts of oral and poster reports presented at the 14th International Conference "Gas Discharge Plasmas and Their Applications" (GDP 2019). This event is a continuation of conferences on gas discharge physics held in Russia since 1984, as well as seminars and conferences on the technological application of low-temperature plasma. The conference is held every 2 years in different cities of the Russian Federation. This year, the wonderful Siberian city of Tomsk, known for its intellectual environment, was chosen as the venue. The program of the Conference covers a wide range of technical areas and modern aspects of the physical processes occurring in generators of lowtemperature plasma, low and high-pressure discharges, pulsed plasma sources, surface modification, and other gas-discharge technologies

The Fourteenth Annual Conference YUCOMAT 2012: Programme and the Book of Abstracts

The First Conference on materials science and engineering, including physics, physical chemistry, condensed matter chemistry, and technology in general, was held in September 1995, in Herceg Novi. An initiative to establish Yugoslav Materials Research Society was born at the conference and, similar to other MR societies in the world, the programme was made and objectives determined. The Yugoslav Materials Research Society (Yu-MRS), a nongovernment and non-profit scientific association, was founded in 1997 to promote multidisciplinary goal-oriented research in materials science and engineering. The main task and objective of the Society has been to encourage creativity in materials research and engineering to reach a harmonic coordination between achievements in this field in our country and analogous activities in the world with an aim to include our country into global international projects. Until 2003, Conferences were held every second year and then they grew into Annual Conferences that were traditionally held in Herceg Novi in September of every year. In 2007 Yu-MRS formed two new MRS: MRS-Serbia (official successor of Yu-MRS) and MRS-Montenegro (in founding). In 2008, MRS – Serbia became a member of FEMS (Federation of European Materials Societies)

Proceedings of the Scientific-Practical Conference "Research and Development - 2016"

talent management; sensor arrays; automatic speech recognition; dry separation technology; oil production; oil waste; laser technolog

Social work with airports passengers

Social work at the airport is in to offer to passengers social services. The main methodological position is that people are under stress, which characterized by a particular set of characteristics in appearance and behavior. In such circumstances passenger attracts in his actions some attention. Only person whom he trusts can help him with the documents or psychologically