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Chen, Song
Publikasjoner (5 av 5) Visa alla publikasjoner
Chen, S., Abdel-Magied, A. F., Fu, L., Jonsson, M. & Forsberg, K. (2019). Incorporation of strontium and europium in crystals of α-calcium isosaccharinate. Journal of Hazardous Materials, 364, 309-316
Åpne denne publikasjonen i ny fane eller vindu >>Incorporation of strontium and europium in crystals of α-calcium isosaccharinate
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2019 (engelsk)Inngår i: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 364, s. 309-316Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The final repository for short-lived, low and intermediate level radioactive waste in Sweden is built to act as a passive repository. Already within a few years after closure water will penetrate the repository and conditions of high alkalinity (pH 10.5―13.5) and low temperature (< 7 °C) will prevail. The mobility of radionuclides in the repository is dependent on the radionuclides distribution between solid and liquid phases. In the present work the incorporation of strontium (II) and europium (III) in α-calcium isosaccharinate (ISA) under alkaline conditions (pH ~10) at 5 °C and 50 °C have been studied. The results show that strontium and europium are incorporated into α-Ca(ISA)2 when crystallized both at 5 °C and 50 °C. Europium is incorporated to a greater extent than strontium. The highest incorporation of europium and strontium at 5 °C rendered the phase compositions Ca0.986Eu0.014(ISA)2 (2.4% of Eu(ISA)3 by mass) and Ca0.98Sr0.02(ISA)2 (2.2% of Sr(ISA)2 by mass). XPS spectra show that both trivalent and divalent Eu coexist in the Eu incorporated samples. Strontium ions were found to retard the elongated growth of the Ca(ISA)2crystals. The incorporation of Sr2+ and Eu3+ into the solid phase of Ca(ISA)2 is expected to contribute to a decreased mobility of these ions in the repository.

sted, utgiver, år, opplag, sider
Elsevier, 2019
Emneord
Mobility, radionuclides, isosaccharinate, precipitation
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-235920 (URN)10.1016/j.jhazmat.2018.10.001 (DOI)000452926500034 ()30384240 (PubMedID)2-s2.0-85055549831 (Scopus ID)
Forskningsfinansiär
Swedish Radiation Safety Authority, SSM2016-2126
Merknad

QC 20181010

Tilgjengelig fra: 2018-10-08 Laget: 2018-10-08 Sist oppdatert: 2019-05-20bibliografisk kontrollert
Chen, S. & Mihaescu, M. (2019). Nozzle Pressure Ratio Effects on Aerodynamics and Acoustics of a Highly-Heated Rectangular Supersonic Jet. In: 25th AIAA/CEAS Aeroacoustics Conference: . Paper presented at 25th AIAA/CEAS Aeroacoustics Conference (pp. 16). , Article ID AIAA 2019-2753.
Åpne denne publikasjonen i ny fane eller vindu >>Nozzle Pressure Ratio Effects on Aerodynamics and Acoustics of a Highly-Heated Rectangular Supersonic Jet
2019 (engelsk)Inngår i: 25th AIAA/CEAS Aeroacoustics Conference, 2019, s. 16-, artikkel-id AIAA 2019-2753Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Implicit large-eddy simulations (LES) are performed in this work to study the flow-field and acoustic characteristics of a highly-heated rectangular supersonic jet. The focus is on the nozzle pressure ratio(NPR) effects. Three NPRs are investigated including 3.0, 3.67, and 4.0, which correspond to the nozzle over-expansion, perfect-expansion, and under-expansion conditions respectively. The current hot jet has a nozzle temperature ratio (NTR) of 7.0, corresponding to a total temperature of around 2100K. The rectangular nozzle has an aspect ratio of 2.0 and has been extensively tested at the Universityof Cincinnati. An in-house CFD code with an artificial dissipation mechanism is used to perform the large-scale implicit LES computations. By studying the pressure contours, density gradients and dilatation, it is found that the three-dimensional jet shock/expansion wave structure changes signifi-cantly when the jet NPR increases from an over-expanded to under-expanded condition. The length of the laminar shear layer right outside the nozzle is extended to the downstream before transitioning to be turbulent. The distance between the nozzle lip and the first shock cell is doubled while the total number of shock cells keeps the same, which results in a longer jet potential core. The increase of nozzle NPR also provides about an 11% increase in jet velocity and a 25% increase in shear layer convection Mach number, which leads to a stronger Mach wave radiation noise component in the acoustic fields. Pressure spectra in the near field reveal that screech only exists in the over-expansion case and the broadband shock-associated noise is enhanced in the perfect and under expansion cases.The far-field acoustics at 40Deq is characterized by about 4 dB increase of the overall sound pressure level in the Mach wave radiation direction and about 2 – 3 dB increase in all other directions. The far-field pressure spectra also confirm that the screech noise component vanishes when the nozzle NPR is increased to perfect- and under-expanded conditions.

Emneord
Supersonic Jet; Aerocoustics; Large Eddy Simulations; highly-heated jet; Nozzle Pressure Ratio effect; far-field pressure spectra
HSV kategori
Forskningsprogram
Teknisk mekanik; Flyg- och rymdteknik
Identifikatorer
urn:nbn:se:kth:diva-256547 (URN)10.2514/6.2019-2753 (DOI)
Konferanse
25th AIAA/CEAS Aeroacoustics Conference
Merknad

QC 20190828

Tilgjengelig fra: 2019-08-28 Laget: 2019-08-28 Sist oppdatert: 2019-08-28bibliografisk kontrollert
Chen, S. & Zhao, D. (2019). RANS investigation of the effect of pulsed fuel injection on scramjet HyShot II engine. Aerospace Science and Technology, 84, 182-192
Åpne denne publikasjonen i ny fane eller vindu >>RANS investigation of the effect of pulsed fuel injection on scramjet HyShot II engine
2019 (engelsk)Inngår i: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 84, s. 182-192Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Effective and efficient fuel-air mixing plays a critical role in the successful operation of scramjet engines. To enhance the fuel-air mixing in supersonic combustion systems with a short flow residence time, the pulsed fuel injection strategy in a realistic scramjet combustor flow condition provided by the HyShot II is numerically studied in this work. For this, 2D and 3D simulations of the hydrogen fueled HyShot II scramjet with pulsed fuel injections are performed. Emphasis is placed on the cold flow field characteristics and fuel-air mixing performance in the combustor. Reynolds-Averaged Navier-Stokes equations are solved with the implementation of the two equation k-omega SST turbulence model via using the ANSYS FLUENT v17.1. The pulsed fuel injection is numerically achieved by implementing a time-dependent total pressure pulse with the shape of a square wave. The total pressure peak is maintained as same as the one that chokes the fuel injector in steady operations. The numerical model is validated first by comparing the results with the experimental data available in the literature. It is then used to study the effect of the pulse injection with different frequencies. It is found that complicated waves structures are formed inside the fuel injector in pulsed fuel injections due to the total pressure pulse. These waves propagate outside the fuel injector and lead to the fuel streams with wavy patterns and the unsteady shock structures in the combustion chamber. Fuel penetration depths are not found to be increased for pulsed injections in this study, but much high turbulent kinetic energy (TKE) levels are observed especially inside the fuel injector. With the help of increased TKE, mixing efficiency is found to be improved for all of the pulsed fuel injection by up to 30%. This mixing improvement also strongly depends on the frequency applied. 2018 Elsevier Masson SAS. All rights reserved.

sted, utgiver, år, opplag, sider
ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2019
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-243960 (URN)10.1016/j.ast.2018.10.022 (DOI)000456641000014 ()2-s2.0-85055901400 (Scopus ID)
Merknad

QC 20190301

Tilgjengelig fra: 2019-03-01 Laget: 2019-03-01 Sist oppdatert: 2019-03-01bibliografisk kontrollert
Chen, S., Gojon, R. & Mihaescu, M. (2018). High-Temperature Effects on Aerodynamic and Acoustic Characteristics of a Rectangular Supersonic Jet. In: AIAA (Ed.), AIAA/CEAS Aeroacoustics Conference, AIAA AVIATION Forum, 2018: . Paper presented at AIAA/CEAS Aeroacoustics Conference, AIAA AVIATION Forum, (AIAA 2018-3303). , Article ID 3303.
Åpne denne publikasjonen i ny fane eller vindu >>High-Temperature Effects on Aerodynamic and Acoustic Characteristics of a Rectangular Supersonic Jet
2018 (engelsk)Inngår i: AIAA/CEAS Aeroacoustics Conference, AIAA AVIATION Forum, 2018 / [ed] AIAA, 2018, artikkel-id 3303Konferansepaper, Publicerat paper (Fagfellevurdert)
Abstract [en]

Implicit large-eddy simulations (LES) are performed in this work to study the flow field and acous-tic characteristics of a rectangular supersonic jet. The focus is to investigate the high-temperatureeffects, i.e. when the jet total temperature is as high as 2100 K. Four cases with a jet temperatureratio(TR) of 1.0, 2.0, 4.0 and 7.0 are investigated. The rectangular nozzle selected for this study hasan aspect ratio of 2. The jets are overexpanded, with a series of shock cells in the jet core region.An artificial dissipation mechanism is used to damp the numerical oscillation and to represent theeffect of small-scale turbulence. The temperature-dependent thermal properties of air within thehigh-temperature regime are also considered by using the chemical equilibrium assumption. Thenumerical results show that the high temperature significantly increases the jet velocity and acousticMach number, although the jet Mach number is maintained roughly the same. Meanwhile, the lengthof the jet core region of the hot jet (TR = 7.0) is found to be reduced by around 30 %, compared tothe cold jet. The convection velocity and acoustic convection Mach number in the shear layer are alsoobserved to be increased when the jet temperature is high. The elevated acoustic convection Machnumber directly leads to a strong Mach wave radiation, and the crackle noise component has beenidentified by the pressure skewness and kurtosis factors. The Strouhal number of the screech tone isfound to be decreased slightly, and good agreements between the numerical results and the theoreticalanalysis are observed. Moreover, the sound pressure levels (SPL) associated with turbulent mixing,screech, Mach wave radiation, and Broadband shock associated noise are all found to be amplified indifferent levels for the hot jets. In the far field, the SPL is strongly increased by the high-temperatureeffect. Higher SPL is notably observed in the Mach wave radiation directions.

Emneord
Large Eddy Simulation, Supersonic rectangular jets, Aeroacoustics, Temperature effects
HSV kategori
Forskningsprogram
Teknisk mekanik
Identifikatorer
urn:nbn:se:kth:diva-235799 (URN)10.2514/6.2018-3303 (DOI)2-s2.0-85051292277 (Scopus ID)978-1-62410-560-9 (ISBN)
Konferanse
AIAA/CEAS Aeroacoustics Conference, AIAA AVIATION Forum, (AIAA 2018-3303)
Merknad

QC 20181010

QC 20181017

Tilgjengelig fra: 2018-10-04 Laget: 2018-10-04 Sist oppdatert: 2018-10-17bibliografisk kontrollert
Chen, S. & Zhao, D. (2018). Numerical study of non-reacting flowfields of a swirling trapped vortex ramjet combustor. Aerospace Science and Technology, 74, 81-92
Åpne denne publikasjonen i ny fane eller vindu >>Numerical study of non-reacting flowfields of a swirling trapped vortex ramjet combustor
2018 (engelsk)Inngår i: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 74, s. 81-92Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

In this work, 3D numerical investigations of a trapped vortex combustor operated in different swirling flow conditions are performed by solving Reynolds-averaged Navier-Stokes equations with Reynolds-stress model. Emphasis is placed on the non-reacting flowfield characteristics and the stability of the locked vortex. Validation is performed first by comparing the present results with experimental data available. It shows that the Reynolds-stress model can provide good predictions for flows with a swirl number up to 0.98. It is also found that the cavity vortex can be trapped well in flows with different swirl numbers. To further study the "locked" vortices, flow disturbances are introduced to the trapped vortex combustor via suddenly increasing swirl number from 0.6 to 0.98. The transient simulation results reveal that the cavity vortex is highly resistant to the flow disturbances and is still well trapped in the cavity, while vortex shedding of the conventional breakdown vortex is observed in the presence of the flow disturbances. Turbulence intensity and kinetic energy are found to be significantly increased by approximately 300%, which indicates that the fuel-air mixing can be dramatically improved. This study shows that the swirling trapped vortex combustor is an alternative promising robust and efficient combustor concept.

sted, utgiver, år, opplag, sider
Elsevier Masson SAS, 2018
Emneord
Axial Throughflow, Rotating Cavity, Cooling Air, Flow, Computation, Simulation, Expansion, Breakdown, Model
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-224689 (URN)10.1016/j.ast.2018.01.006 (DOI)000426332900009 ()2-s2.0-85041479457 (Scopus ID)
Merknad

QC 20180326

Tilgjengelig fra: 2018-03-26 Laget: 2018-03-26 Sist oppdatert: 2018-03-26bibliografisk kontrollert
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