Fant 9887 publikasjoner. Viser side 315 av 396:
2001
Simulation of volcanic ash ingestion into a large aero engine: particle–fan interactions
Volcanic ash (VA) clouds in flight corridors present a significant threat to aircraft operations
as VA particles can cause damage to gas turbine engine components that lead to a
reduction of engine performance and compromise flight safety. In the last decade,
research has mainly focused on processes such as erosion of compressor blades and
static components caused by impinging ash particles as well as clogging and/or corrosion
effects of soft or molten ash particles on hot section turbine airfoils and components.
However, there is a lack of information on how the fan separates ingested VA particles
from the core stream flow into the bypass flow and therefore influences the mass concentration
inside the engine core section, which is most vulnerable and critical for safety. In
this numerical simulation study, we investigated the VA particle–fan interactions and
resulting reductions in particle mass concentrations entering the engine core section as a
function of particle size, fan rotation rate, and for two different flight altitudes. For this,
we used a high-bypass gas-turbine engine design, with representative intake, fan, spinner,
and splitter geometries for numerical computational fluid dynamics (CFD) simulations
including a Lagrangian particle-tracking algorithm. Our results reveal that
particle–fan interactions redirect particles from the core stream flow into the bypass
stream tube, which leads to a significant particle mass concentration reduction inside the
engine core section. The results also show that the particle–fan interactions increase
with increasing fan rotation rates and VA particle size. Depending on ingested VA size
distributions, the particle mass inside the engine core flow can be up to 30% reduced
compared to the incoming particle mass flow. The presented results enable future calculations
of effective core flow exposure or dosages based on simulated or observed atmospheric
VA particle size distribution, which is required to quantify engine failure
mechanisms after exposure to VA. As an example, we applied our methodology to a
recent aircraft encounter during the Mt. Kelud 2014 eruption. Based on ambient VA concentrations
simulated with an atmospheric particle dispersion model (FLEXPART), we
calculated the effective particle mass concentration inside the core stream flow along the
actual flight track and compared it with the whole engine exposure.
2019
We conducted a theoretical analysis of the relationship between red-to-blue (RBR) color intensities and aerosol optical properties. RBR values are obtained by radiative transfer simulations of diffuse sky radiances. Changes in atmospheric aerosol concentration (parametrized by aerosol optical depth, AOD), particle’s size distribution (parametrized by Ångström exponent, AE) and aerosols’ scattering (parametrized by single scattering albedo—SSA) lead to variability in sky radiances and, thus, affect the RBR ratio. RBR is highly sensitive to AOD as high aerosol load in the atmosphere causes high RBR. AE seems to strongly affect the RBR, while SSA effect the RBR, but not to such a great extent.
2023
2002
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2012
2005
Svalbard Integrated Arctic Earth Observing System (SIOS) is an international partnership of research institutions studying the environment and climate in and around Svalbard. SIOS is developing an efficient observing system, where researchers share technology, experience, and data, work together to close knowledge gaps, and decrease the environmental footprint of science. SIOS maintains and facilitates various scientific activities such as the State of the Environmental Science in Svalbard (SESS) report, international access to research infrastructure in Svalbard, Earth observation and remote sensing services, training courses for the Arctic science community, and open access to data. This perspective paper highlights the activities of SIOS Knowledge Centre, the central hub of SIOS, and the SIOS Remote Sensing Working Group (RSWG) in response to the unprecedented situation imposed by the global pandemic coronavirus (SARS-CoV-2) disease 2019 (COVID-19). The pandemic has affected Svalbard research in several ways. When Norway declared a nationwide lockdown to decrease the rate of spread of the COVID-19 in the community, even more strict measures were taken to protect the Svalbard community from the potential spread of the disease. Due to the lockdown, travel restrictions, and quarantine regulations declared by many nations, most physical meetings, training courses, conferences, and workshops worldwide were cancelled by the first week of March 2020. The resumption of physical scientific meetings is still uncertain in the foreseeable future. Additionally, field campaigns to polar regions, including Svalbard, were and remain severely affected. In response to this changing situation, SIOS initiated several operational activities suitable to mitigate the new challenges resulting from the pandemic. This article provides an extensive overview of SIOS’s Earth observation (EO), remote sensing (RS) and other operational activities strengthened and developed in response to COVID-19 to support the Svalbard scientific community in times of cancelled/postponed field campaigns in Svalbard. These include (1) an initiative to patch up field data (in situ) with RS observations, (2) a logistics sharing notice board for effective coordinating field activities in the pandemic times, (3) a monthly webinar series and panel discussion on EO talks, (4) an online conference on EO and RS, (5) the SIOS’s special issue in the Remote Sensing (MDPI) journal, (6) the conversion of a terrestrial remote sensing training course into an online edition, and (7) the announcement of opportunity (AO) in airborne remote sensing for filling the data gaps using aerial imagery and hyperspectral data. As SIOS is a consortium of 24 research institutions from 9 nations, this paper also presents an extensive overview of the activities from a few research institutes in pandemic times and highlights our upcoming activities for the next year 2021. Finally, we provide a critical perspective on our overall response, possible broader impacts, relevance to other observing systems, and future directions. We hope that our practical services, experiences, and activities implemented in these difficult times will motivate other similar monitoring programs and observing systems when responding to future challenging situations. With a broad scientific audience in mind, we present our perspective paper on activities in Svalbard as a case study.
Earth observation; Remote sensing; COVID-19; Svalbard; Earth System Science; SIOS
MDPI
2021
2022
2019
Royal Society of Chemistry (RSC)
2022
2007
2012
SK-1401 Mongstad. Spredningsberegninger. NILU OR
Norsk Institutt for luftforskning (NILU) har gjort spredningsberegninger av utslipp til luft fra skorstein SK-1401 på Mongstad. Spredning av, CO2 og SO2 er beregnet og analysert. Det er også gjort en vurdering knyttet til helse- og miljøeffekter inkludert levetid/nedbrytningstid for de aktuelle utslippskomponentene. De beregnede konsentrasjonene har blitt sammenholdt med eksisterende bakgrunnskonsentrasjoner og sammenlignet med gjeldende grenseverdier. For det definerte Worst Case utslippscenariet vil grenseverdi for timemidlet SO2-konsentrasjon kunne overskrides. En alternativ utforming av utslippet er beregnet, maksimalkonsentrasjonen for denne utformingen er 2/3 lavere enn opprinnelig Worst Case og overskrider ikke grenseverdien.
2012
SK-1531 Mongstad. Spredningsberegninger og HMS-vurdering. NILU OR
Norsk Institutt for luftforskning (NILU) har gjort spredningsberegninger av utslipp til luft fra skorstein SK-1531 på Mongstad. Spredning av NH3, HCN, CO, CO2, NO2, SO2 og benzen er beregnet og analysert. Det er også gjort en vurdering knyttet til helse- og miljøeffekter inkludert levetid/nedbrytningstid for de aktuelle utslippskomponentene. De beregnede konsentrasjonene har blitt sammenholdt med eksisterende bakgrunnskonsentrasjoner og sammenlignet med gjeldende grenseverdier. Ingen av de undersøkte komponenter overskrider grenseverdier. Utslippene fra SK-1531 ansees derfor ikke å utgjøre noe problem.
2011
Skadelige mengder av dette kjemikaliet lekker ut av mat- og drikkeemballasje
Norges forskningsråd
2025