京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20412号 / 工博第4349号 / 新制||工||1674(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 松田 建児, 教授 澤本 光男 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20714号 / 工博第4411号 / 新制||工||1685(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 村上 正浩, 教授 松田 建児 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21778号 / 工博第4595号 / 新制||工||1716(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 木村 俊作, 教授 瀧川 敏算, 教授 大内 誠 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

No description available.

No description available.

Temperature control is an essential aspect of gear design. Continuous research is going on to improve the efficiency of gear systems. Power losses or energy losses in these systems typically manifest themselves as increased temperatures and thus reducing the lifetime and overall performance of the system. Siemens Energy gas turbines produce powers of up to 63 Megawatts and as a result requires a gearbox which can transmit such high powers. A double helical parallel shaft gearbox is mostly used for this purpose. With sufficient cooling methods and by reducing the losses in the gearboxes even by a minute percent, can increase the efficiency of gearbox which in turn will increase the efficiency of the whole powerplant. This will make the consumer even more profitable in the long run. A mathematical power loss model for the double helical gears in mesh was developed in MATLAB. This was followed by a finite element steady state thermal analysis in ANSYS. The boundary conditions and the results of the analysis are discussed and a few design changes to reduce the gear losses are suggested. / Temperaturkontroll är en viktig aspekt av växeldesign. Kontinuerlig forskning pågår för att förbättra växelsystemens effektivitet. Effektförluster eller energiförluster i dessa system manifesterar sig vanligtvis som ökade temperaturer och minskar därmed systemets livslängd och totala prestanda.  Siemens Energy gasturbiner producerar effekter på upp till 63 megawatt och kräver därför en växellåda som kan överföra så höga effekter. En växellåda med dubbel spiralformad parallellaxel används mest för detta ändamål. Med tillräckliga kylmetoder och genom att minska förlusterna i växellådorna även med en minutprocent, kan öka växellådans effektivitet vilket i sin tur kommer att öka effektiviteten i hela kraftverket. Detta kommer att göra konsumenten ännu mer lönsam på lång sikt. En matematisk effektförlustmodell för de dubbla spiralformade kugghjulen i nät utvecklades i MATLAB. Detta följdes av ett finit element steady state termisk analys i ANSYS. Randvillkoren och resultaten av analysen diskuteras och några designändringar för att minska växelförlusterna föreslås.

The objective of this research is to determine the three-dimensional stiffness matrix of a rectangular cross-section helical coil compression spring. The stiffnesses of the spring are derived using strain energy methods and Castigliano's second theorem. A theoretical model is developed and presented in order to describe the various steps undertaken to calculate the spring's stiffnesses. The resulting stiffnesses take into account the bending moments, the twisting moments, and the transverse shear forces. In addition, the spring's geometric form which includes the effects of pitch, curvature of wire and distortion due to normal and transverse forces are taken into consideration. Similar methods utilizing Castigliano's second theorem and strain energy expressions were also used to derive equations for a circular cross-section spring. Their results are compared to the existing solutions and used to validate the equations derived for the rectangular cross-section helical coil compression spring. A finite element model was generated using IDEAS (Integrated Design Engineering Analysis Software) and the stiffness matrix evaluated by applying a unit load along the spring's axis, then calculating the corresponding changes in deformation. The linear stiffness matrix is then obtained by solving the linear system of equations in changes of load and deformation. This stiffness matrix is a six by six matrix relating the load (three forces and three moments) to the deformations (three translations and three rotations). The natural frequencies and mode shapes of a mechanical system consisting of an Additional mass and the spring are also determined. Finally, a comparison of the stiffnesses derived using the analytical methods and those obtained from the finite element analysis was made and the results presented. / Master of Science

Around the world, countries are increasingly considering carbon-free energy generation options as the threat of climate change grows. Small modular reactor designs, promising such carbon-free energy generation, are thriving worldwide with novel and innovative technologies that improve safety as well as economic performance. Canada is also considering small modular reactors (SMRs) as a means of achieving net zero carbon emissions by 2050. Some of these reactor designs utilize pressurized water for cooling and moderator. Reactors with pressurized water have been subjected to steam generator tube ruptures in the past, and a detailed investigation into the possible consequences of such incidents in SMRs should be conducted. In this research, a model for one of the newer designs, the NuScale Integrated Small Modular Reactor, was developed with the RELAP5-3D code for assessing safety related transients. The NuScale Small Modular Reactor incorporates helical coil steam generators within its reactor pressure vessel, which are more efficient in terms of heat transfer than the U-tube steam generators that are widely used in nuclear reactors. In the first part of the research, a detailed model is created and used to obtain steady state conditions with parameters collected from NuScale’s Final Safety Analysis Report (FSAR). The Steam Generator Tube Rupture event is analyzed in the second part of the work. Slight differences in the broken and intact steam generator pressures as well as decay heat removal system flow rates are seen in the comparison of reference values and calculated results. Among the reasons for those differences could be that the correlations used by the RELAP5-3D code for heat transfer coefficient and pressure drop in the helical coil steam generators are different than those of the NuScale proprietary code NRELAP5, with which the analyses have been performed in the FSAR. Also, post-dryout heat transfer at the exit of helical coil steam generators and evaporator sections could cause differences in the outlet conditions of the steam, resulting in different mass flow rates as well. The final section of the research simulates a comparable but more severe tube rupture incident without the availability of decay heat removal systems in order to assess the reactor’s emergency core cooling system reaction. Passive decay heat removal systems are crucial components for removing heat after reactor shutdown through heat exchangers that are submerged in the reactor pool and connected to steam generators by a closed loop. The containment pressures, the containment wall temperatures, and the peak fuel clad temperatures are considered to be the key design constraints that must be observed. Future work on this subject could include modifying the source code, adding specific correlations for helical coil steam generators, and comparing the results, as well as quantifying uncertainties in the SGTR event. Main parameters in the quantification of uncertainties would be reactor power, single phase and two-phase discharge coefficients from the break, trip signals and delays as well as break size and location. / Thesis / Master of Applied Science (MASc)

No description available.

No description available.