研究者詳細 - 横森　剛

論文 - 横森　剛

分割表示 89 件中 1 - 20 件目／全件表示 >>

Numerical study on propagation and NO reduction behavior of laminar stratified ammonia/air flames

Tomidokoro T., Yokomori T., Im H.G.

Combustion and Flame （Combustion and Flame） 241 2022年07月

ISSN 00102180

In recently developed ammonia combustion technologies such as swirl flow and staged combustion, locally rich or lean pockets of unburned mixtures may occur due to insufficient mixing. This results in a premixed flamelet propagating into a gradually leaner or richer mixture. The present study aims to numerically investigate the propagation of laminar ammonia/air premixed flames in compositionally stratified mixtures. Results indicate that the flame speed in a rich-to-lean stratified mixture is increased from that in corresponding homogeneous mixtures at each local equivalence ratio. In contrast, the stratified flame speed is decreased in a lean-to-rich stratified mixture. The response of the stratified flame speed is attributed to variation in the amount of H2 in the burned gas. In the rich-to-lean stratified flame, an extra amount of H2 diffuses into the reaction zone to enhance chain-branching reactions which produce H radicals. The increased H radicals then promote dehydration reactions, resulting in an increased fuel consumption rate. In the lean-to-rich stratified flame, the opposite process takes place. The above mechanism is similar to the so-called back-support effect observed in methane/air stratified flames. Meanwhile, in both rich-to-lean and lean-to-rich stratified flames, additional NO reduction occurs in the stoichiometric region of the burned gas. This is facilitated by unburned ammonia diffusing from the neighboring rich burned gas mixing with O/H radicals diffusing from the neighboring lean burned gas, resulting in a production of extra NHi radicals which readily reduce NO. Therefore, NO emission in stratified flames is expected to be lower than that estimated from the emission characteristics in homogeneous mixtures. Although similar to the well-known thermal DeNOx mechanism, the current NO reduction process occurs under a much higher temperature due to the abundance of radical species. A similar phenomenon is expected to be observed in a triple flame configuration, which requires future investigations.

Access to Document (DOI)

Experimental Investigation of the Effects of Fuel Injection on the Cycle-to-Cycle Variation of the In-Cylinder Flow in a Direct-Injection Engine Using High-Speed Particle Image Velocimetry Measurement

Kaneko Y., Nagashima T., Tomidokoro T., Matsuda M., Yokomori T.

SAE International Journal of Engines （SAE International Journal of Engines） 15 （ 6 ） 2022年02月

ISSN 19463936

In a direct-injection (DI) engine, the in-cylinder flow is complex. Fluctuations of DI and in-cylinder flow, and the relationships between those fluctuations, are considered to affect the cycle-to-cycle variation (CCV) of combustion. However, neither the relationship between the injection conditions and the CCV of the in-cylinder flow nor the effect of the in-cylinder tumble flow on the spray has been clarified in detail. In this study, a single-cylinder optical engine was used to perform high spatial resolution particle image velocimetry (PIV) measurements and to photograph spray behavior throughout the cylinder. The spray timing was changed to investigate the timing's effects on the in-cylinder flow, the CCV, and tumble vortex center behavior. The penetration length was calculated from the spray images and compared with the PIV measurement results. The PIV results showed that the behavior of the bulk flow in the cylinder, the position of the center of the tumble vortex, and the CCV of the velocity changed depending on the presence or absence of DI and the injection timing. The overall trend was that the shorter the time elapsed after injection, the stronger the effect on the in-cylinder flow remained. The results of spray imaging revealed that the ambient flow velocity affected the direct spray at the time of injection when the flow velocity was high in the spray direction and that the spray extended faster. In addition to the advantage of the longer diffusion time, the fast in-cylinder flow in the same direction as the direct jet did not cause much momentum exchange with the spray, while making it easier for the spray to diffuse throughout.

Access to Document (DOI)

火炎を用いたコアシェル粒子合成技術

横森剛, 富所拓哉

日本燃焼学会誌（一般社団法人日本燃焼学会） 63 （ 205 ） 201 - 209 2021年

ISSN 1347-1864

Core shell particles comprise a core content and a coating shell of another material. The core shell structure can realize a new functional material that cannot be realized by a particle which has only a single composition. Wet chemical synthesis is commonly used in the fabrication of core–shell particles, but recently, some reports on flame aerosol synthesis of core-shell particles have been published. Flame aerosol synthesis can offer continuous one-step production process including high-temperature treatment, and results in high-purity fine crystalline particles. Therefore, it is expected that flame aerosol synthesis method for core-shell particles will be further developed in the future. In this paper, we explain the details of flame aerosol synthesis method for core-shell particles and give an interpretation of the physical processes.

共添加燐光体における異波長ライフタイム特性とその２波長ライフタイム同時測定による温度測定性能向上

松下佑樹, 横森剛

日本機械学会関東支部総会講演会講演論文集（一般社団法人日本機械学会） 2021 （ 0 ） 10A15 2021年

The effects of co-doping in phosphors and the use of co-doped phosphors to extend the temperature measurement range were experimentally investigated in terms of the lifetime method. Such effects can be evaluated by comparing the single and double luminescent centers. In this study, YAG:Tb, YAG:Cr and YAG:Cr,Tb were prepared by sol-gel method and the luminescence intensity was measured under excitation by the 4th harmonic of Nd:YAG laser. In order to improve the temperature measurement performance of YAG:Cr,Tb, it is desirable to divide it into two wavelength regions with a threshold around 600 nm, and to switch between the two regions depending on the temperature range when performing temperature measurement by the lifetime method. The absolute lifetime sensitivity SA is a suitable index to use when dividing the temperature region into two regions, resulting in switching at around 800 K. The lifetime of the Cr-derived luminescence is slightly longer, while that of the Tb-derived luminescence is about 10 times shorter.

リーンバーンSIエンジンにおけるノッキング検出精度向上に関する研究

岡田力也, 安武優希, 御代川慎司, 富所拓哉, 横森剛

日本機械学会関東支部総会講演会講演論文集（一般社団法人日本機械学会） 2021 （ 0 ） 10A16 2021年

The purpose of this study was to improve the accuracy of knock detection for lean burn SI engines. In this study, we conducted an experiment to observe autoignition in an engine cylinder using a borescope and a high-speed camera under an air excess ratio of 2.1. In addition, the resonance frequency of each vibration mode by knocking and the knock intensity were also calculated from the in-cylinder pressure history. Autoignition was optically observed in all cycles with a knock intensity of more than 20 kPa or more, and in some cycles with that of less than 20 kPa. We compared the vibration caused by combustion and it caused by autoignition. As a result, by distinguishing between the vibration caused by combustion and it caused by autoignition using window functions, a knocking cycle that could not be detected by the conventional index was detected.

Characteristics of counterflow premixed flames with low frequency composition fluctuations

Tomidokoro T., Yokomori T., Im H., Ueda T.

Combustion and Flame （Combustion and Flame） 212 13 - 24 2020年02月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00102180

© 2019 The Combustion Institute The response of laminar methane/air counterflow premixed flames under sinusoidal equivalence ratio oscillation was investigated numerically. The timescales of the oscillation were chosen to be sufficiently longer than the flame timescale so that the flame responds quasi-steadily. The response of periodically stratified flame (SF) with a detailed reaction mechanism exhibited the “back-support” effect, in that the consumption speed Sc response deviated increasingly from Sc of steady homogeneous flames (HFs) at higher oscillation frequencies. It was shown that even when the imposed oscillation timescale is much longer than the flame timescale, the flame response can still be delayed under a sufficiently large equivalence ratio gradient. Subsequently, the above results were compared with those obtained with a global four-step mechanism that omits back-diffusion radicals into the reaction zone. As a result, SFs with the global mechanism displayed a much smaller back-support effect in both lean and rich mixtures. Further analysis with modified diffusion coefficients revealed the dominant roles of H2 and radical species diffusion in inducing the back-support effect. Contrary to the previous findings, variations in burned gas temperature were found to play a negligible role in modifying Sc. Additionally, the hysteresis of the back-support effect under periodical stratification was found to be more prominent on the richer side because of the presence of a larger H2 pool.

Access to Document (DOI)

Precision evaluation of phosphors for the lifetime method in phosphor thermometry

Kazuki Tsuchiya, Kento Sako, Naohiro Ishiwada, and Takeshi Yokomori

Measurement Science and Technology （Measurement Science and Technology） accepted （ 6 ） 2020年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 09570233

© 2020 IOP Publishing Ltd. The precision of the lifetime method in phosphor thermometry was examined in terms of the uncertainty in temperature prediction. Such uncertainty can be estimated using the rate of change in lifetime with temperature (lifetime sensitivity) and the uncertainty in measured lifetime. This uncertainty depends on phosphorescence characteristics such as phosphorescence intensity and lifetime decay shape. In this study, we proposed a method of calculating uncertainties in measured lifetimes by the estimated regression coefficients in measured decay signals of phosphors. To demonstrate this evaluation, the uncertainties in the predicted temperatures of some common phosphors (MFG, GGG:Cr, Y2O3:Eu) were calculated. Consequently, the temperature predictions by the lifetime method with MFG, GGG:Cr, and Y2O3:Eu showed high precision at about 800 K, 700 K, and 900 K, respectively. This method of evaluating precision by using both lifetime sensitivity and uncertainty in lifetime helps to improve the appropriate use of phosphors for the lifetime method in phosphor thermometry.

Access to Document (DOI)

天然ガスの組成変化を伴うブンゼン火炎の応答とその制御

梅沢修一, 石橋卓也, 岡本倫一, 横森剛, 植田利久

日本機械学会論文集（一般社団法人日本機械学会） 86 （ 884 ） 19 - 00432-19-00432 2020年

共著

This study investigated experimentally a response of premixed Bunsen flame to transient change in a fuel composition and a method to control the variation. Fuel mixtures were composed of methane, ethane and propane. The volumetric fraction of methane was varied from 92 % to 76 % by 4 % and the ethane/propane ratio was 5. Transition time of the fuel composition was 1, 5, 10 and 20 s. Flow velocity and the equivalence ratio were 0.8 m/s and 0.85 respectively before the transition. Channel length L between the merging point of fuels and the point of air was 0, 500, 1000, 1500 mm. The motion of flame was recorded by a high-speed video camera at 60 fps. The experiment was conducted under the fuel flow rate constant and the equivalence ratio constant conditions. In the former condition, the flame height varied almost linearly not depending on the conditions. In the latter condition, variation of the steady flame height was smaller than the former condition. However, the unsteady flame height exceeded or fell below temporarily the steady flame height. This is due to the time lag between the transmission of fuel flow rate variation and fuel compositions variation. Therefore, considering this time lag, the experiment was conducted with a system which had a density meter to detect the fuel composition variation. The system controlled automatically the fuel flow rate. At long L and short transition time, there were some peaks in the flame height variation. It is considered that this is caused by the difference between the actual density and the output of the density meter due to Taylor dispersion and response time of the density meter. However, the flame height variation was smaller than the variation without control, and particularly at long transition time, the variation was suppressed sufficiently.

Response of a heat and moisture exchanger containing CaCl2 to the periodic change of flow direction

Okinaga Yoshihito, Murata Makoto, Ueda Toshihisa, Yokomori Takeshi

MECHANICAL ENGINEERING JOURNAL （一般社団法人日本機械学会） 7 （ 1 ） 19 - 00335-19-00335 2020年

共著, ISSN 2187-9745

The characteristics of a medical heat and moisture exchanger with filter (HMEF) that contained polyurethane sponges and CaCl2 were investigated experimentally and model analysis was performed. Variations in the temperature and humidity were measured. Saturated air at 37 °C simulating exhalation and dry air at 26 °C simulating inhalation were fed alternatively through the HMEF in opposite directions. The period was set as 256 s, 64 s, 16 s and 4 s. When the period was long (256 and 64 s), the polyurethane sponges and CaCl2 played an important role in condensation and evaporation of water and the amplitudes of the temperature variation was so large that it overshot the input condition. When the period was shortened (4 s), the amplitudes of the temperature and humidity variations decreased and the relative humidity of the patient side of the HMEF gradually reached that of the exhalation conditions. This suggests that the characteristic times of condensation and evaporation were longer than that of the respiration (τb = 4 s). In other words, the unsteady effect is important for the condensation and vaporization mechanism of HMEF. The mechanism was supported by the model analysis. In addition, comparing the results of the experiments and model analysis elucidated the effect of the connecting pipe, which corresponds to the dead space effect in clinical use.

Thermal efficiency improvement of super-lean burn spark ignition engine by stratified water insulation on piston top surface

Nagasawa T., Okura Y., Yamada R., Sato S., Kosaka H., Yokomori T., Iida N.

International Journal of Engine Research （International Journal of Engine Research） accepted （ 5 ） 1421 - 1439 2020年

研究論文（学術雑誌）, 共著, ISSN 14680874

© IMechE 2020. In order to improve thermal efficiency of spark ignition engine under super-lean burn conditions (excess air ratio (Formula presented.)), thermal stratification technique by in-cylinder water injection toward piston surface (stratified water insulated combustion architecture), in which low temperature water vapor layer is formed on the surface, is proposed. From the water spray visualization using the optically accessible engine, injected water is distributed near the piston top surface at ignition timing and thermal stratification can be achieved in the case that water injection timing (SOIw) is set at earlier stage of a compression stroke. In addition, heat flux on the piston surface measured at the same time is reduced by water injection. The 0.5-L single-cylinder engine test at λ = 2.0 at a constant ignition timing also shows that water injection at earlier stage of a compression stroke makes it possible to mitigate knock without significant increase in combustion instability. On the other hand, part of water is distributed near the spark plug at ignition timing with the water injection at SOIw = −60 °ATDC, resulting in unstable combustion. In addition, the engine test at λ = 2.0 and water/fuel ratio(W/F) = 18% shows that knock mitigation by water injection enables spark advance and following combustion enhancement. As a result, combustion period becomes short and cooling loss decreases, followed by the 1.0-pt improvement of gross indicated thermal efficiency. Moreover, the engine can be operated at minimum spark advance for best torque by increasing W/F up to 35%. Finally, stratified water insulated combustion architecture concept is applied at λ = 1.9 with a higher compression ratio of 17, showing that water injection at SOIw = −120 °ATDC and W/F = 50% enables minimum spark advance for best torque operation, and remarkably high gross indicated that thermal efficiency of 52.63% can be achieved with a sufficiently low knock level and coefficient of variation of indicated mean effective pressure.

Access to Document (DOI)

Development of cycle-to-cycle variation of the tumble flow motion in a cylinder of a spark ignition internal combustion engine with Miller cycle

Matsuda M., Yokomori T., Shimura M., Minamoto Y., Tanahashi M., Iida N.

International Journal of Engine Research （International Journal of Engine Research） 22 （ 5 ） 1512 - 1524 2020年

共著, ISSN 14680874

© IMechE 2020. Reducing the cycle-to-cycle variation in an engine is a key to expanding the operational limits of high-efficiency engines such as lean-burn engines. The cycle-to-cycle variation of the engine output is caused by unstable combustion and is especially induced by the cycle-to-cycle variation of the in-cylinder flow. This investigation aims to clarify how the cycle-to-cycle variation of in-cylinder flow develops during intake and compression strokes. To achieve this aim, 12 kHz time-resolved particle image velocimetry measurements were conducted on the symmetrical vertical plane in a four-valve, four-stroke optically accessible engine. This study focuses on the relationship between the flow at the plug position at the ignition timing and the flow distribution in the intake and compression stroke. Correlation map analysis reveals this relationship, and some flow distributions are extracted. The fluctuations in the flow distribution induce the cycle-to-cycle variation of the flow direction at the plug position at the ignition timing, the position of the stagnation plane between the intake flow from the intake valves and the upper side of the tumble vortex, the strength of the blowback flow into the intake port generated by the Miller cycle, and the position of the tumble vortex in the late compression stroke. The flow distributions extracted by the correlation map analysis clearly change between cycles. These results also suggest that correlation map analysis is an effective way to elucidate the factors that induce the cycle-to-cycle variation of the in-cylinder flow.

Access to Document (DOI)

A computational analysis of strained laminar flame propagation in a stratified CH<inf>4</inf>/H<inf>2</inf>/air mixture

Tomidokoro T., Yokomori T., Ueda T., Im H.G.

Proceedings of the Combustion Institute （Proceedings of the Combustion Institute） 38 （ 2 ） 2543 - 2550 2020年

共著, ISSN 15407489

© 2020 The Combustion Institute. Propagation of a H2-added strained laminar CH4/air flame in a rich-to-lean stratified mixture is numerically studied. The back-support effect, which is known to enhance the consumption speed of a flame propagating into a leaner mixture compared to that into a homogeneous mixture, is evaluated. A new method is devised to characterize unsteady reactant-to-reactant counterflow flames under transiently decreasing equivalence ratio, in order to elucidate the influence of flow strain on the back-support effect. In contrast to the conventional reactant-to-product configurations, the current configuration is more relevant to unsteady stratified flames back-supported by their own combustion products. Moreover, since H2 distribution downstream of the flame is known to play a crucial role in back-supported CH4/air flames, the influence of H2 addition in the upstream mixture is examined. The results suggest that a larger strain rate leads to a larger equivalence ratio gradient at the reaction zone through increased flow divergence, which amplifies the back-support. Meanwhile, since H2 addition in the upstream mixture does not affect the downstream H2 content, the relative increase in the consumption speed, i.e. the back-support, is suppressed with larger H2 addition. Especially, when the upstream H2 content decreases with the equivalence ratio, the H2 preferentially diffuses toward the unburned gas, which mitigates H2 accumulation in the preheat zone and further weakens the back-support.

Access to Document (DOI)

A new pattern of flame/flow dynamics for lean-premixed, low-swirl hydrogen turbulent jet flames under thermoacoustic instability

Shoji T., Tachibana S., Suzuki T., Nakazumi Y., Yokomori T.

Proceedings of the Combustion Institute （Proceedings of the Combustion Institute） 38 （ 2 ） 2835 - 2843 2020年

研究論文（学術雑誌）, 共著, ISSN 15407489

© 2020 The Combustion Institute. Published by Elsevier Inc. This paper presents a phenomenological investigation of a new pattern of lean-premixed hydrogen-flame and flowfield dynamics under thermoacoustic instabilities (TIs) observed inside a low-swirl combustor (LSC) with two combustion chamber lengths of 300 and 500 mm. In this study, the initial bulk inlet velocity was set to V m = 15 m/s. The fuel flow rate was linearly increased while the air flow rate was kept constant, causing a transition from stable operation to TI. Simultaneous time-resolved electronically excited hydroxyl radical (OH *) chemiluminescence imaging and two-dimensional particle image velocimetry were performed along with pressure-fluctuation measurements to investigate spatiotemporal relationships between fluctuating quantities, i.e., OH * chemiluminescence, velocity fields, and pressure, before and after TI onset. A typical TI pattern characterized by a lifted, inverted conical flame caused by diverging, decelerating flow near the injector exit was observed in the long combustor. In contrast, the flame/flow dynamics pattern under TI in the short combustor had strong pressure oscillations and anomalous LSC flame structures which were characterized by a radially flat flame region and counter-rotating vortex pair (CVP) flame structures. In this case, the radial profile of the axial velocity assumed an atypical top-hat-like shape. This feature resulted in thermoacoustic coupling that satisfied the Rayleigh criterion over an almost entirely flat flame region and further strengthened the TI. Thermal expansions of CVP structures served as "converging nozzles" constricting the central flow region. Periodic appearances of this Venturi-like effect caused an alternating diverging (decelerating) and converging (accelerating) flowfield, with a significant peak-to-peak velocity-oscillation amplitude of 15 m/s, equivalent to V m . These pioneering observations regarding LSCs provide further insights into TI mechanisms in hydrogen-fueled gas turbine combustors.

Access to Document (DOI)

Effects of flame behaviors on combustion noise from lean-premixed hydrogen low-swirl flames

Shoji T., Iwasaki Y., Kodai K., Yoshida S., Tachibana S., Yokomori T.

AIAA Journal （AIAA Journal） 58 （ 10 ） 4505 - 4521 2020年

研究論文（学術雑誌）, 共著, ISSN 00011452

© 2020 by Takeshi Shoji, Yuki Iwasaki, Kato Kodai, Seiji Yoshida, Shigeru Tachibana, and Takeshi Yokomori. This experimental study explored the influence of global/local flame behaviors on direct combustion noise produced by a lean-premixed gaseous H2 ∕air low-swirl turbulent jet flame, with a focus on the mechanism resulting in characteristic peaks in combustion noise spectra. Ten kilohertz OH chemiluminescence and OH planar laser-induced fluorescence (OH-PLIF) imaging were used to study the spatiotemporal evolution of heat release and flame structure fluctuations, respectively, whereas 2-D particle image velocimetry (2-D PIV) measurements at 4 Hz were applied to study the mean-based relation between the velocity/vorticity fields and flame structures. Pressure and global heat release fluctuation measurements carried out alongside these optical diagnostics revealed pronounced double peaks in both combustion noise and global heat release fluctuation spectra at global equivalence ratios of ϕ ≥ 0.45. Spectral proper orthogonal decomposition of the OH chemiluminescence and OH-PLIF images revealed that the first peak in the noise spectra to be caused by flame oscillations over nearly the entire flame region, whereas the secondary peak was attributed to periodically generated vortical flame structures near the downstream side of the flame boundary. The 2-D PIV results suggest that vortical flame structures are likely generated by the interaction between the flame and the inner/outer shear layers.

Access to Document (DOI)

Effects of flame structures on direct combustion noise produced by lean-premixed h<inf>2</inf> /air low-swirl jet flames

Shoji T., Iwasaki Y., Kodai K., Yoshida S., Tachibana S., Yokomori T.

AIAA Scitech 2020 Forum （AIAA Scitech 2020 Forum） 1 PartF 2020年

研究論文（国際会議プロシーディングス）, 共著, ISSN 9781624105951

© 2020, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. This experimental study explored the influence of flame structural characteristics on direct combustion noise produced by a lean-premixed gaseous H2 /air low-swirl turbulent jet flame, with a focus on the mechanism resulting in characteristic peaks in combustion noise spectra. Ten-kHz OH* chemiluminescence and OH planar laser-induced fluorescence (OH-PLIF) imaging were used to study the spatiotemporal evolution of heat release and flame structure fluctuation, respectively, while two-dimensional particle image velocimetry (2D-PIV) measurements at 4 Hz were used to study the mean-based relation between the velocity/vorticity fields and flame structures. Pressure and global heat release fluctuation measurements carried out alongside these optical diagnostics revealed pronounced double peaks in both combustion noise and global heat release fluctuation spectra at global equivalence ratios of ϕ ≥ 0.45. Spectral orthogonal decomposition of the OH* chemiluminescence and OH-PLIF images revealed the first peak in the noise spectra to be caused by flame oscillations over nearly the entire flame region, while the secondary peak is attributed to periodically generated vortical flame structures near the flame boundary. The 2D PIV results suggest that vortical flame structures are probably generated by the interaction between the flame and the inner/outer shear layers.

Access to Document (DOI)

高速度OH-PLIF計測を用いたリーンバーンガソリンエンジンにおける初期火炎伝播の解析

松田昌祥, 長島朋来, 横森剛, 志村祐康, 店橋護

熱工学コンファレンス講演論文集（一般社団法人日本機械学会） 2020 （ 0 ） 0185 2020年

共著

This paper describes the ignition and early flame propagation in a high-tumble SI IC engine under super lean-burn condition (excess air ratio (λ) of 2.0). To elucidate the detail process, a high-tumble optically-accessible SI IC engine operating at super lean and stoichiometric conditions were diagnosed by time-resolved OH-PLIF measurements. The engine was operated 2000 rpm with a port fuel injection of isooctane. The cross-sectional imaging of OH distribution was achieved at 12 kHz resulting in a temporal resolution of 1° crank angle at 2000 rpm. The results show that the OH radical is generated without any heat release by the spark discharge during approximately 15 ° crank angle after ignition timing in the super-lean condition. The OH distribution of these crank angles are scatted into small islandlike areas, and then subsequent flame propagation occurs.

燐光体を利用した温度計測の基礎と原理

横森剛, 石和田尚弘

日本燃焼学会誌（一般社団法人日本燃焼学会） 62 （ 201 ） 234 - 241 2020年

学位論文（博士）, 共著, ISSN 1347-1864

Accurate and reliable temperature measurements are crucial to improve the thermal efficiency and optimize the design of products because temperature is an important parameter to understand heat conduction, convention, radiation, and chemical reactions. The emission properties of phosphors are sensitive to temperature, hence, phosphor thermometry can make remote temperature sensing. Accordingly, phosphor thermometry has received considerable attention as a versatile alternative to conventional temperature measurement techniques. This article describes the principles and fundamental aspects of phosphor thermometry, that is, principles of luminescence, temperature dependences of luminescence characteristics and how to use those dependence characteristics such as life time method and spectral intensity ratio method.

タンブル流強化ガソリンエンジンにおける高速マイクロPIVとMEMS熱流束センサの同時計測

横山瑛士, 鎌田慎, 志村祐康, 中別府修, 横森剛, 店橋護

熱工学コンファレンス講演論文集（一般社団法人日本機械学会） 2020 （ 0 ） 0071 2020年

共著

In order to understand the effect of velocity boundary layer on the heat loss in a tumble enhanced engine, simultaneous measurements of high-speed microscopic particle image velocimetry (PIV) near the piston top and a micro electro mechanical systems (MEMS) heat flux sensor on the piston surface was conducted in the motored optical engine with enhanced tumble flow. This engine was rotated at2000 rpm. Experimental results show the correlation between the velocity fluctuation and the peak value of heat flux, and the correlation coefficient shows higher value at 0.50 mm from the piston wall rather than 0.27 mm and 0.12 mm.

タンブル流強化ガソリンエンジンにおけるピストン頂面近傍の流動と壁面熱流束の相関

中別府修, 鎌田慎, 横山瑛士, 志村祐康, 横森剛, 店橋護

熱工学コンファレンス講演論文集（一般社団法人日本機械学会） 2020 （ 0 ） 0192 2020年

共著

Heat transfer inside an engine has been studied for improving thermal efficiency by mitigation of the cooling loss. Flow near a piston top and heat flux on it were simultaneously measured with a microPIV and a MEMS thin film sensor in a motoring mode of an optical engine. It was confirmed that averaged heat flux over -15~15 CA deg. showed a positive correlation to the normal flow fluctuation, and that the instantaneous wall heat flux showed obvious correlation to the instantaneous normal velocity at 0.5 mm above the wall with a time lag of 200 s level. Moreover, a combination analysis of the wall parallel velocity and FFT spectrum of the heat flux showed that the fluctuation in the heat flux is composed of temperature unevenness of several millimeter scale and eddy motion of several hundred micrometer.

Development of cycle-to-cycle variation of the tumble flow motion in a cylinder of an SI IC engine with Miller cycle

Masayoshi Matsuda, Takeshi Yokomori, Masayasu Shimura, Yuki Minamoto, Mamoru Tanahashi, Norimasa Iida

International Journal of Engine Research accepted 2020年

査読有り

　前のページ - 次のページ　

横森 剛

論文 - 横森 剛

横森　剛

論文 - 横森　剛