Numerical analysis of heat transfer characteristics of spray flames impinging on a wall under CI engine-like conditions

Design of Compression Ignition (CI) engines with improved thermal efficiencies needs better understanding of the heat transfer mechanism from spray flame to the combustion chamber wall. In this regard, heat transfer occurring during the interaction between impinging spray flame and wall, under CI engine-like conditions, is investigated in this study using 3-Dimensional numerical simulations based on an Eulerian–Lagrangian framework. Simulations are performed for different fuel spray injection velocities (which are representative of different fuel injection pressures in CI engines), to examine their influence on the heat transfer between impinging spray flame and wall. To couple the convective and radiative heat transfer at the wall surface with the conduction heat transfer occurring within the finite thickness wall, Conjugate Heat Transfer (CHT) is incorporated in the simulations. A Non-Adiabatic Flamelet/Progress Variable (NA-FPV) approach is employed as the combustion model of n-dodecane, which is considered to be the fuel for liquid spray. Dynamics of the liquid film formed on the wall surface by impinging fuel droplets are captured using a particle-based approach. Contribution of radiative heat flux is taken into consideration using the Discrete Ordinates (DO) method. Results indicate that the total heat flux (sum of convective and radiative heat fluxes) at the wall surface increases with the fuel injection velocity. It is observed that the total wall heat flux is largest in the stagnation zone where the spray flame impinges directly on the wall surface, while the radiative heat flux at the wall surface becomes larger as the distance from this stagnation zone increases. Additionally, it is found that the influence of fuel injection velocity on the radiative heat flow rate at the wall surface is rather small. This radiative heat flow rate when expressed as a percentage of the total wall heat flow rate, ranges from ≈ 18% to 30% (depending on the 3 cases investigated), indicating that its contribution cannot be neglected for the CI engine-like conditions under which the present simulations are performed. Furthermore, to characterize the heat transfer occurring during spray flame-wall interaction process, correlations between the Nusselt number Nu (corresponding to the wall heat loss) and Reynolds number Re (of the flow field) of the form Nu ∝ Re, are analysed and compared with that of a previous experimental study to assess their applicability. It is found that, depending on how the Nusselt number Nu is defined (either using the total wall heat flux or the convective heat flux), the value of the correlation index n changes. When Nu is calculated based on the total wall heat flux (which includes the contribution from the radiative heat flux), the value of n is found to be 0.49 which is close to the correlation index value of n = 0.4 reported in the recent experiments performed at Toyota Central R&D Labs., Inc

Development of Phonon Dynamics Measurement System by MIR- FEL and Pico-second Laser

FEL2015, Daejeon, Republic of KoreaCoherent control of a lattice vibration in bulk solid (mode-selective phonon excitation: MSPE) is one of the attractive methods in the solid state physics because it becomes a powerful tool for the study of ultrafast lattice dynamics (e.g. electron-phonon interaction and phonon-phonon interaction). Not only for that, MSPE can control electronic, magnetic, and structural phases of materials. In 2013, we have directly demonstrated MSPE of a bulk material with MIR-FEL (KU-FEL) by anti-Stokes Raman scattering spectroscopy. For the next step, we are starting a phonon dynamics measurement to investigate the difference of physical property between thermally excited phonon (phonon of equilibrium state) and optically excited phonon (phonon of non-equilibrium state) by time-resolved method in combination with a pico-second VIS laser. By using pico-second laser, we also expect to perform the anti-Stokes hyper-Raman scattering spectroscopy to extend MSPE method to the phonon mode which has Raman inactive . As the first step, we have commissioned the time-resolved phonon measurement system and started measurement on 6H-SiC. In this conference, we will present the outline of measurement system, and experimental results

How did Japanese teachers deal with COVID-19 in their lessons?: The case studies of two teachers

This article illustrates how two Japanese teachers design and implement a unit related to COVID-19 for promoting teaching controversial issues in Japan. We discovered the following two implications for achieving the aim: (a) improving teachers’ abilities of explaining how the issues are necessary and important in school education and (b) enhancing the ability of gatekeeping of teachers. Particularly, the ability of curriculum management is significant for teaching controversial issues.本研究は，JSPS科研費19K14239の助成，および令和二年度教育学部共同研究プロジェクト「ポストコロナの学校教育」の提起する学術知共創の可能性と課題」の支援を受けたものである

Applicability of radiocolloids, blue dyes and fluorescent indocyanine green to sentinel node biopsy in melanoma

Patients with primary cutaneous melanoma underwent sentinel node (SN) mapping and biopsy at 25 facilities in Japan by the combination of radiocolloid with gamma probe and dye. Technetium-99m (99mTc)-tin colloid, 99mTc-phytate, 2% patent blue violet (PBV) and 0.4% indigo carmine were used as tracers. In some hospitals, 0.5% fluorescent indocyanine green, which allows visualization of the SN with an infrared camera, was concomitantly used and examined. A total of 673 patients were enrolled, and 562 cases were eligible. The detection rates of SN were 95.5% (147/154) with the combination of tin colloid and PBV, 98.9% (368/372) with the combination of phytate and PBV, and 97.2% (35/36) with the combination of tin colloid or phytate and indigo carmine. SN was not detected in 12 cases by the combination method, and the primary tumor was in the head and neck in six of those 12 cases. In eight of 526 cases (1.5%), SN was detected by PBV but not by radiocolloid. There were 13 cases (2.5%) in which SN was detected by radiocolloid but not by PBV. In 18 of 36 cases (50%), SN was detected by radiocolloid but not by indigo carmine. Concomitantly used fluorescent indocyanine green detected SN in all of 67 cases. Interference with transcutaneous oximetry by PVB was observed in some cases, although it caused no clinical trouble. Allergic reactions were not reported with any of the tracers. 99mTc-tin colloid, 99mTc-phytate, PBV and indocyanine green are useful tracers for SN mapping.ArticleJOURNAL OF DERMATOLOGY. 39(4):336-338 (2012)journal articl