Browsing by Author "Silde, Ari"
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- APROS-ohjelmiston suojarakennusmallin kehittäminen ja kelpoistaminen
Helsinki University of Technology | Master's thesis(1999) Valpas, RikuTämä diplomityö käsittelee APROS-ohjelmistossa toteutetun yksiulotteiseen virtausratkaisuun perustuvan ns. Iumped parameter -mallin kehittämistä ydinvoimalaitosten suojarakennuksille. Työ on jatkoa aiemmin tehdyille diplomi- ja lisensiaatintöille. Algoritmien vaatimattoman laskentanopeuden sekä fysikaalisten mallien puutteiden vuoksi suojarakennusmalli vaati huomattavaa lisäkehitystä. Diplomityössä saatettiin malli tasolle, jolla sitä voidaan hyödyntää kaupallisesti sekä tutkimustyössä. Suojarakennusmalli kelpoistettiin kahden VICTORIA-koelaitteiston sekä yhden Marviken-koelaitteiston kokeen avulla. VICTORIA-koelaitteisto on 1:15 suhteessa rakennettu malli Loviisan voimalaitoksen suojarakennuksesta. Ensimmäisessä kokeessa jäälauhdutinovet toimivat normaalisti. Tässä tapauksen onnistunut simulointi vaatisi 3-ulotteista virtauslaskentaa, sillä virtaus jäälauhduttimessa on hyvin kanavoitunutta. Osaksi tästä syystä APROS ei pystynyt realistisesti toistamaan koetta, vaan jäälauhduttimien jää suli liian nopeasti. Toisessa kokeessa jäälauhdutinovet pakotettiin auki, jolloin syntyi luonnonkiertovirtaus jäälauhduttimien kautta. Tämän tapauksen APROS laski hyvin. Marvikenin koelaitteisto on alunperin rakennettu kiehutusvesireaktorivoimalaitokseksi, mutta sitä ei ole koskaan otettu käyttöön. Kokeessa kuivatilaan syötettiin höyryn ja veden seosta paineastiasta. APROS laski tapauksen hyvin. - Experimental Characterisation of Sprays Resulting from Impacts of Liquid-Containing Projectiles
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2015) Hostikka, Simo; Silde, Ari; Sikanen, Topi; Vepsä, Ari; Paajanen, Antti; Honkanen, Markus - Experimental characterisation of sprays resulting from impacts of liquid-containing projectiles
School of Engineering | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2015) Hostikka, Simo; Silde, Ari; Sikanen, Topi; Vepsä, Ari; Paajanen, Antti; Honkanen, MarkusModelling and analysing fires following aircraft impacts requires information about the behaviour of liquid fuel. In this study, we investigated sprays resulting from the impacts of water-filled metal projectiles on a hard wall. The weights of the projectiles were in the range of 38–110 kg, with 8.6–68 kg water, and the impact speeds varied between 96 and 169 m/s. The overall spray behaviour was observed with high-speed video cameras. Ultra-high-speed cameras were used in backlight configuration for measuring the droplet size and velocity distributions. The results indicate that the liquid leaves the impact position as a thin sheet of spray in a direction perpendicular to the projectile velocity. The initial spray speeds were 1.5–2.5 times the impact speed, and the Sauter mean diameters were in the 147–344 μm range. This data can be used as boundary conditions in CFD fire analyses, considering the two-phase fuel flow. The overall spray observations, including the spray deceleration rate, can be used for validating the model. - Nuclear power plant passive containment cooling system simulation in Apros
Kemian tekniikan korkeakoulu | Master's thesis(2022-10-10) Värä, ArinaAs nuclear power plants are constantly evolving, so does the safety equipment intended to mitigate effects of a postulated accident. In particular, the containment structure of an NPP is intended to withstand temperature and pressure spikes during accidents as one of defense-in-depth mechanisms. In order to study thermohydraulic phenomena in the containment vessel and efficiency of its cooling systems, research groups conduct experiments, results of which may be validated using computational tools by comparing experiments with computational data. The aim of this thesis is to simulate the experiments of the OECD/NEA HYMERES-2 project on cooling of a containment vessel using Apros. The accurateness of simulation results was reached by testing different heat and mass transfer correlations to correctly replicate thermohydraulic phenomena of experiments. The model was based on the description of the containment vessel and on experimental data provided by the HYMERES-2 project team. Validation of simulation results was done by plotting and analysing the data against experimental results. Based on the analysis, the default Nusselt natural convection correlation was determined to be the most accurate for capturing the experimental phenomena. The comparison of simulation and experimental results showed Apros to be able to accurately replicate the experiment, although the results presented limitations of the lumped parameter method to reproduce the gas flow behaviour inside the containment vessel. For future research, where containment conditions would differ in flow velocities, it is recommended to perform sensitivity analyses using different heat and mass transfer correlations, as well as to consider possible limitations affecting model results. Additionally, a completely new heat and mass transfer correlation may be implemented for future modelling practices in Apros. - Voimalaitosoperaattorin toimenpiteiden vaikutus vakavan reaktorionnettomuuden kulkuun ja seurauksiin
Helsinki University of Technology | Master's thesis(1988) Silde, Ari