Kyushu University Academic Staff Educational and Research Activities Database
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Hiroshi Tashima Last modified date:2020.08.06



Graduate School
Undergraduate School


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Homepage
https://kyushu-u.pure.elsevier.com/en/persons/hiroshi-tajima
 Reseacher Profiling Tool Kyushu University Pure
http://www.eee.kyushu-u.ac.jp/takasaki/front.htm
English version available .
Phone
092-583-7592
Fax
092-583-7593
Academic Degree
Doctor of Engineering
Field of Specialization
Engineering of Engine and Combusition
Outline Activities
Outline of research
Considering improvements on thermal efficiency and combustion technique of engine systems are urgently needed to solve environmental or energy-related problems over the world, main objects of the research field are focused as follows.
* High-speed Visualization and Image Processing of Engine Combustion
* Numerical Simulation of Combustion and Performance of Engines
* Development of Combustion Technique to Utilize Low-grade Heavy Fuel
* Investigation of Combustion Characteristics of Biomass or Recycled Fuel
Outline of education
Opening the following courses in Interdisciplinary Graduate School of Engineering Sciences
* Control of Gas Temperature and Thermal Load
* Exercises in Engine System
* Experiments in Engine System
* Exercises in Presentation
Having the following lectures in Dep. Energy Science and Engineering in School of Engineering
* Dynamics of Vibration
* Analysis of Energy Conversion
* Exercises of Energy Engineering I-III
* Exercises of Basic Mathematics II
* Exercises of Intensive Research Subject
* Exercises of Creative and Scientific Engineering I, II
* Future Soft Energies
Outline of social activities
Having an extension lecture for citizens in Interdisciplinary Graduate School of Engineering Sciences
Research
Research Interests
  • Combustion Characteristics of Premixed Lean-burn Engines of Large Dimensions
    keyword : Natural Gas, Gas Engine, Premixed Combustion, Lean-burn, Knocking
    2008.10.
  • Development and validation of simulation models of unsteady spray combustion
    keyword : Numerical simulation, Spray, Combustion, Internal combustion engine,KIVA,FIRE
    1999.10Unsteady spray flame in diesel engines has been a tough goal for numerical simulations because of its requirements of various models for spray breakup/impingement, pre-ignition/auto-ignition process and locally premixed/diffusive combustion. In this study, proper models and technique for the application of water-emulsified fuel or independent water injection are developed on KIVA III code or Star-CD code, which are generally used in internal combustion engines, and evaluated by comparing experimental results from an actual test engine..
  • Combustion improvement of biomass fuel for effective energy utilization
    keyword : Biomass, Biodiesel, Used cooking oil, Combustion
    2000.04~2004.03Biomass fuels are becoming a key for the future energy logistics thanks to its carbon-neutral characteristics, although the search for their optimal usage is still under way to reduce HC and NOx emission and to settle them in neat oil or in mixture with petroleum fuels. In this study, various techniques including water emulsification, stratified injection with heaver fuels and independent pilot injection, for example, are tested in an actual engine and evaluated by practical measures..
  • Measurement of temperature distribution in diesel flame by 2 color-method using C-MOS camera
    keyword : C-MOS camera, two-color method, diesel flame, temperature measurement
    2003.04~2005.10Color visualization of engine combustion has been a tough task for digital devices because of its severe requirement in resolution and processing speed. C-MOS camera has become a promising substitute for high-speed film camera for that purpose. In this study, a newly introduced C-MOS camera was tested to evaluate its potential as a high-speed photo device. Furthermore, flame temperature measurement on the two-color method is attempted in order to evaluate its color fidelity and to clarify the difference in analysis procedures. All in all, measurement results showed its strong potential for high-speed visualization..
Current and Past Project
  • Keeping the ocean transportation in safety has become a key issue nowadays because of the constant trend in decreasing the skilled crews and in soaring their payments, so that development of the supporting system or auto-navigating system for ship maneuvering are urgently needed. The main purpose of this project is to propose a new hybrid ocean transportation system, which combines a fully automatic navigation with a skilled human piloting to a high degree.
Academic Activities
Books
1. Hiroshi Tashima, Koji Takasaki, 45 authors in all, Series Title:Green Energy,Technology
Book Title:Hydrogen Energy Engineering
Book Subtitle:A Japanese Perspective
, Springer, Chapter 25, 2016.10.
Presentations
1. 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..
2. 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.
3. 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.
4. H. Tashima, Methane slip reduction from marine gas engines by stratified oxygen concentration using gas permeation membrane, 28th CIMAC World Congress, 2016.06.
Educational
Educational Activities
Opening the following courses in Interdisciplinary Graduate School of Engineering Sciences
* Control of Gas Temperature and Thermal Load
* Exercises in Engine System
* Experiments in Engine System
* Exercises in Presentation
Having the following lectures in Dep. Energy Science and Engineering in School of Engineering
* Dynamics of Vibration
* Analysis of Energy Conversion
* Exercises of Energy Engineering I-III
* Exercises of Basic Mathematics II
* Exercises of Intensive Research Subject
* Exercises of Creative and Scientific Engineering I, II
* Future Soft Energies
Social
Professional and Outreach Activities
Having an extension lecture for citizens in Interdisciplinary Graduate School of Engineering Sciences.