Application of alcohol vapour as atomizing fluid in a micro gas turbine burner

Liquid fuels have to be atomized before combustion. In micro gas turbines twin-fluid atomizers are widely used for this purpose. In this type of atomizers generally high velocity air flow disintegrates the liquid fuel stream into droplets, but superheated vapour can also be applied as atomizing fluid. In our experiments a burner of a Capstone C30 micro gas turbine was used, which was built into a test rig developed by us. During measurements diesel oil was used as liquid fuel. Atomizing fluids were air and aqueous ethyl alcohol vapour at different pressures. In every combustion experiment, emissions of carbon monoxide, unburned hydrocarbons and nitrogen oxides were measured. The results showed that application of alcohol vapour as atomizing fluid instead of air improves the quality of combustion. Increasing the atomizing pressure up to a defined optimum value also reduces emissions significantly

Nap típusú csillagok korai fejlődési szakaszainak vizsgálata = Study of early evolutionary stages of Solar type stars

1. A V1647 Ori 2004. januártól 2005. októberig tartó kitörését nemzetközi együttműködéssel, több műszerrel követtük. Analizáltuk a csillag fényességének és színképvonalainak változását a kitörés alatt, és infravörösben az elhalványodás után is, egészen 2006. szeptemberéig. 2. Nap típusú fiatal csillagokat és protocsillagokat azonosítottunk a Lynds 1333, Lynds 1622, Lynds 1340 közeli molekulafelhőkben és a Cepheus flare óriás molekulafelhő-komplexum mintegy 200 négyzetfoknyi területén. Az objektumok nagy része korábban nem ismert fiatal csillag. Saját spektroszkópiai és fotometriai méréseink alapján meghatároztuk a fiatal csillagok spektráltípusát, luminozitását, tömegét és korát. Középinfravörös (Spitzer Space Telescope) adatbázis alapján vizsgáltuk az akkréciós korongjaik tulajdonságait, ezek környezetfüggését. 3. A Spitzer Space Telescope középinfravörös adatainak feldolgozásával vizsgáltuk az NGC 2244 fiatal nyílthalmaz szerkezetét és a halmaztagok akkréciós korongjainak tulajdonságait. 337 fősorozat előtti csillagot és 25 I osztályú protocsillagot azonosítottunk. Spitzer és HST mérések alapján elemeztük a por elpárolgásának folyamatát a forró csillagok közelében. A h és chi Persei Spitzer-adatainak elemzésével megállapítottuk, hogy a 24 mikronon megfigyelhető törmelékkorongok tipikus kora 5 és 15 millió év között van. 4. A pályázat támogatásával elkészült egy kis felbontású spektrográf a piszkés-tetői RCC teleszkópra. | 1. We followed the outburst of V1647 Ori between 2004 January and 2005 October using several instruments. We analysed the variations of the brightness and spectral line intensities during the outburst, and even after the dimming of the star in the infrared, up to 2006 September. 2. We identified Solar type young stars and protostars in the nearby molecular clouds Lynds 1333, Lynds 1622, as well as over the whole surface of some 200 square degrees of the Cepheus flare molecular complex. Most of the objects are newly identified young stars. Based on our own spectroscopic and photometric observations we determined the spectral types, luminosities, masses, and ages of the stars. Based on the mid-infrared Spitzer Space Telescope archive data we studied their accretion disks, and the dependence of disk properties on the environment. 3. We studied the structure of the young open cluster NGC 2244 based on the mid-infrared data obtained by the Spitzer Space Telescope. We identified 337 pre-main sequence stars and 25 Class I protostars. Based on Spitzer and HST measurements we analysed the evaporation of the dust in the vicinity of hot stars. Based on Spitzer observations of the open cluster h and chi Persei we established that the typical age of the debris disks observed at 24 micron is 5-15 million years. 4. A low-resolution spectrograph has been devised and built for the RCC telescope with the support of this project

Effect of Quarls on the Blowout Stability and Emission of Pollutants of a Liquid-Fueled Swirl Burner

Stringent emissions standards for NOx and carbon monoxide (CO) prompt lean combustor development. With this motivation, combustion stability issues emerge since the desired operating point approaches the lean blowout limit. In this paper, an atmospheric, 15 kW lean premixed prevaporizing-type swirl burner, equipped with a plain jet airblast atomizer, was investigated at various atomizing pressures and combustion air flow rates, using quarls from 0 deg to 60 deg in 15 deg steps. Both the 15 deg and the 30 deg quarls provided a 42% higher lean blowout stability on average in terms of mean mixing tube discharge velocity, compared to the baseline burner. However, the superior stability regime was encumbered by a rapidly increasing CO emission. In parallel, the NOx emission vanished due to the more dilution air and incomplete combustion. The 60 deg quarl provided a moderately extended blowout stability limitation, while the NOx emission slightly increased and the CO emission reduced compared to the baseline burner.</jats:p

Exploring the circumstellar environment of the young eruptive star V2492 Cygni

Context. V2492 Cyg is a young eruptive star that went into outburst in 2010. The near-infrared color changes observed since the outburst peak suggest that the source belongs to a newly defined sub-class of young eruptive stars, where time-dependent accretion and variable line-of-sight extinction play a combined role in the flux changes. Aims. In order to learn about the origin of the light variations and to explore the circumstellar and interstellar environment of V2492 Cyg, we monitored the source at ten different wavelengths, between 0.55 μm and 2.2 μm from the ground and between 3.6 μm and 160 μm from space. Methods. We analyze the light curves and study the color–color diagrams via comparison with the standard reddening path. We examine the structure of the molecular cloud hosting V2492 Cyg by computing temperature and optical depth maps from the far-infrared data. Results. We find that the shapes of the light curves at different wavelengths are strictly self-similar and that the observed variability is related to a single physical process, most likely variable extinction. We suggest that the central source is episodically occulted by a dense dust cloud in the inner disk, and based on the invariability of the far-infrared fluxes, we propose that it is a long-lived rather than a transient structure. In some respects, V2492 Cyg can be regarded as a young, embedded analog of UX Orionis-type stars.Conclusions. The example of V2492 Cyg demonstrates that the light variations of young eruptive stars are not exclusively related to changing accretion. The variability provided information on an azimuthally asymmetric structural element in the inner disk. Such an asymmetric density distribution in the terrestrial zone may also have consequences for the initial conditions of planet formation