||Daisuke TSURU, Hiroshi TASHIMA , Study on combustion of ammonia direct injection assisted by diesel spray, 第90回マリンエンジニアリング学術講演会, 2020.10.
||Takahide Aoyagi, Daisuke Tsuru, Hiroshi Tashima, A Study of combustion behavior in premixed lean-burn gas engine, 6th International Conference on Fossil and Renewable Energy, 2020.02.
||Hiroshi Tashima, Recent trends of low-speed marine diesels and some relevant studies in QU
, the third Low-speed marine engine technology development conference, 2019.12.
||Hiroshi Tashima, Consideration of Engine Size Effects on Heat Loss by Comparison of Various Diesels, Twelfth Engine Researchers Forum in Wuxi, 2019.05.
||Hiroshi Tashima, Takahide Aoyagi, Daisuke Tsuru, Kousuke Okazaki, Combustibility Investigation of Future Low-Sulphur Fuel for Marine Propulsion, 3rd International Conference on Gas, Oil and Petroleum Engineering, 2019.02.
||Hiroshi Tashima, Daisuke Tsuru, Ryosuke Ishibashi,, Consideration of Engine Size Effects on Heat Loss Focusing Large Low-Speed Marine Diesels, the 5th Rostock Large Engine Symposium, 2018.09, Large low-speed marine diesels outperform any other combustion engines working on a single heat cycle with their ultimate thermal efficiency up to 55% even on the lower calorific value of the fuel. The main reason has been considered to lie in their less heat-loss nature, and they actually lose only about 10% of the fuel energy through the chamber wall. Although their smaller surface-to-volume (SV) ratio or a “Square-cube law” is apt to be pointed as the theoretical ground, the law is not good enough to explain the nature because efficiencies and losses of piston engines should be discussed not per unit time (ex. hour or day) but per one engine cycle. This means the lower revolution of larger engines may offset the merit of their smaller SV ratio.
As for heat transfer aspects, many heat transfer models have been proposed to give reasonable estimation of the heat transfer between in-cylinder gas and chamber walls. Those models have been developed and validated in smaller engines. However, small high-speed diesels and large low-speed diesels differ entirely both in wall configuration and spray layout over the combustion chamber. To make matters worse, model parameters are usually optimized from engine to engine. All in all, it has to be said the less heat-loss nature of large diesels is only an empirical fact that has not been made theoretically clear. In this study, backgrounds of the heat loss issues of piston engines were investigated in detail thorough two approaches.
At first, a comprehensive survey was done to check the adaptability of a similarity law from high-speed small diesels to low-speed large diesels. The survey revealed that marine low-speed engines rotate much more slowly than the others, and therefore they have longer cycle time than expected on their bore size. The SV ratio and other indexes were also sampled and discussed.
Second, heat transfer models were equally adopted to a small high-speed engine (100 mm bore, 2000 rpm) and a large low-speed engine (400 mm bore, 140 rpm) with keeping model parameters exactly the same. In the first stage, a 1D engine simulator with a macro heat transfer model; Woschni model was adopted. Although the heat transfer model includes the engine size effect as minus two tenth power of the bore size, the simulator overestimated the heat loss of the large engine especially in the late expansion stroke. In the second stage, a combination of a 3D CFD code with a boundary-layer-based heat transfer model; Han-Reitz model was adopted to reflect the real chamber configuration and the spray specifications. The results finally showed good agreement with the expectation of the heat losses for the both engines and succeeded to clarify the background of the difference between them..
||Hiroshi Tashima, Ryosuke Ishibashi, Daisuke Tsuru, An Optical Investigation of Combustion Process of a Direct High-Pressure Injection of Natural Gas, 2nd International Conference on Gas, Oil and Petroleum Engineering, 2018.02.
||H. Tashima, T. Nishijima, M. Yamamoto, M. Tsukui, I. Komemo, D. Tsuru, Effects of Fuel Property and Engine Control System on Engine Output in Shop Trial and Sea Trial, ISME Tokyo 2017, 2017.10.
||T. Thiripuvanam, H. Tashima, D. Tsuru, Air Entrainment and Combustion Process of High-Pressure Gas Jet in Gas Direct Injection Engines, 9th International Symposium COMODIA 2017, 2017.07.
||H. Tashima, D. Tsuru, Y. Shintani, Air entrainment of high pressure methane gas and effects of nozzle diameter and injection pressure, 18th ILASS-Asia, 2016.11.
||H. Tashima, D. Tsuru, Application of reactivity stratified compression ignition to large size gas engine, THIESEL 2016, 2016.09.
||H. Tashima, D. Tsuru, Effects of momentum increase by inert additives on jet and spray combustion characteristics, 28th ILASS-Europe, 2016.09.
||H. Tashima, Methane slip reduction from marine gas engines by stratified oxygen concentration using gas permeation membrane, 28th CIMAC World Congress, 2016.06.
||H. Tashima, D. Tsuru, Combustion prediction of marine residual oil of low ignitibility on two-component fuel model, SAE 2014 PFL Meeting, 2014.10.
||Daisuke Tsuru, Ryosuke Ishibashi, Hiroshi Tajima, The investigation of air entrainment and development of diesel-like gas jet under engine condition, The 26th European Conference on Liquid Atomization and Spray Systems, 2014.09.
||K. Komada, H. Tajima, D. Tsuru, D. Sakaguchi, H. Ueki
, Effect of needle lift on atomization in diesel fuel spray, THIESEL 2014, 2014.09.
||H. Tajima, D. Tsuru, Methane slip reduction from natural gas engines by oxygen stratification using gas permeation membrane, THIESEL 2014, 2014.09.
||R. Ishibashi, D. Tsuru, H. Tajima, Effects of ambient pressure and temperature on penetration of a high compressed gas jet in high density conditions, 26th ILASS-Europe, 2014.09.
||T. Fujino, S. Kawakita, W. Kondo, Y. Nishijima, D. Tsuru, H. Tajima
, Observation of spray interference and combustion process of gas direct injection engine with double-needle type injector, 26th ILASS-Europe, 2014.09.
||D. Tsuru, R. Ishibashi, H. Tajima, The investigation of air entrainment and development of diesel-like gas jet under engine condition, 26th ILASS-Europe, 2014.09.
||Keisuke Komada, Hiroshi Tajima, Daisaku Sakaguchi, Hironobu Ueki, Masahiro Ishida, Study on Simulation of Diesel Fuel Spray Based on L2F Measurement, 16th Annual Conference of ILASS-Asia, 2013.12.
||Hiroshi Tajima, Daisuke TSURU, Reduction of Methane Slip from Gas Engines by O2 Concentration Control using Gas Permeation Membrane, SAE/KSAE 2013 Powertrains, Fuels & Lubricants Meeting, 2013.10.
||Keisuke Komada, Takashi Yamada, Hiroshi Tajima, Daisaku Sakaguchi, Hironobu Ueki, Masahiro Ishida, Study on Cyclic Variation in near-Nozzle Region of Diesel Spray by L2F, ILASS – Europe 2013, 25th European Conference on Liquid Atomization and Spray Systems, 2013.09.
||Daisuke TSURU, Keisuke Komada, Ryousuke Ishibashi, Hiroshi Tajima, Investigation of Spray Combustion with Fuel-Water Emulsification under Exhaust Gas Recirculation using Detailed Visualization and Spray Modelling, ILASS – Europe 2013, 25th European Conference on Liquid Atomization and Spray Systems, 2013.09.
||Hiroshi Tajima, Daisuke TSURU, Koji Takasaki, Dino Imhof, High-Pressure Natural Gas Injection (GI) Marine Engine Research with a Rapid Compression Expansion Machine, 27th CIMAC World Congress on Combustion Engines, 2013.05.
||Hiroshi Tajima, Daisuke TSURU, Potential Investigation of PCCI Combustion as NOx Reduction Measure at Low-load Operation with Low-CN LCO Fuel, 27th CIMAC World Congress on Combustion Engines, 2013.05.
||Numerical study of the influence of inhomogeneous mixture distribution on combustion process
In order to control the rapid combustion process in Premixed Charge Compression Ignition (PCCI) combustion, the present study investigates the influence of the inhomogeneous mixture distribution on the combustion process based on ID Computational Fluid Dynamics (CFD) with detailed chemical kinetic reaction model.
Inhomogeneous mixture in the computational region was expressed by the spatial distribution of air/fuel mixture and the range of air/fuel equivalence ratio. As the uniform mixture gets inhomogeneous with the steeper gradient of equivalence ratio in stratified distribution, rapid combustion process becomes slower. However, too steep gradient of equivalence ratio makes the combustion process rapid because spontaneous reaction occurs locally in the area where the mixture with high equivalence ratio exists.
||Effects of Oxygen Dilution and Water Injection on Combustion and NOx Emission of Low-Speed Diesel Engines.
||Hiroshi Tajima, Satoshi Kawauchi, Daisuke TSURU, Dino Imhof, Kimihiko Sugiura, Investigation of Knocking Phenomena of Large Gas Engine through Visualization and Simulation of Combustion Process, 8th International Colloquium Fuels, 2011.01.