Koji Korematsu

Flame Propagation into the Ring Crevice of a Spark Ignition Engine

Unreacted fuel in ring crevice volumes is a significant source of hydrocarbon emissions from spark ignition engines. If the ring crevice is designed with a wider clearance into which the flame will propagate, the unreacted fuel can be reduced. In this paper, the conditions of flame propagation into the ring crevice are investigated by using ionization probes imbedded in the moving piston of a four-stroke spark ignition engine. It is found that the flame propagates into the ring crevice if the quenching distance when the flame reaches the crevice is narrower than the piston top land clearance.

Study on Behavior of Birchley-Riley's Fuel Droplet Heated in the Electric Furnace.

As a Birchley-Rileys fuel droplet consisted of an aqueous core embedded within a liquid fuel shell was heated in the electric furnace, the puffing and the microexplosion were observed. The waiting time for microexplosion was dominated by water content, droplet volume, fuel type and ambient temperature. When the waiting time data plot was fitted by Weibull distribution, its shape parameter was equal to 2 and the microexplosion phenomenon was classified as wear out failure type.

DUAL FUELED DIESEL ENGINE WITH DIESEL FUEL AND REFORMED METHANOL

A dual fueled diesel engine system with diesel fuel and reformed methanol has been investigated. Methanol can be reformed to reformed methanol (hydrogen 67% + carbon monoxide 33%) over suitable catalyst. The reformed methanol contains 20% more energy than methanol. Fundamental data of an electric heated reformer, performance of the dual fueled diesel engine to which hydrogen and carbon monoxide fed from gas bombs as a preliminary experiment, and then performance of the diesel engine with an onboard reformer were tested. In consequence, the feed of the reformed methanol improves the diesel engine performance.

Performance Estimation of Partial Admission Turbines

The new relationships of partial admission losses which account for influence of all major geometric parameters of concern to the turbine designer are presented, based on fluid dynamic analysis of the losses. The performance maps are presented showing the trends in efficiencies that are attainable in turbine designed over a wide range of loading, axial velocity/blade speed ratio, Reynolds number, and aspect ratio. Finally, the question of partial admission versus low aspect ratio is discussed.Copyright

Experimental Study on Dioxins in Exhaust Gas of Diesel Engines

It is sometimes pointed out that Dioxins (DXNs) are contained in the exhaust gas of diesel engines. In the current stage the experimental data of DXNs from diesel engines are insufficient in order to understand their mechanism and how to reduce their generation. This paper describes the measuring results of the emitted DXNs from the diesel engine and the effect of the chlorine sources on them. The experimental result shows that the DXNs from engine and incinerator is same level when the amount of chlorine would be equalized in two combustion fields. It is found that the simple relation Y=AXB is established between DXNs concentration in the particulate matter from the diesel engine Y and the amount of chlorine in the combustion field X where the values of A and B are the expgrental constants. The relation shows it is possible to bring the DXNs from diesel engines close to the zero, if the chlorine in the motor oil and the fuel, and sea salt particles in inductien air is, cut off.

Effect of Idling Stop at Traffic Signals on Fuel Consumption of Gasoline Engine Vehicles-Period of Idling Stop and Amount of Saved Fuel-

Given that the atmospheric emission of CO2 is the worst cause of global warming, improving automobile fuel consumption can have positive effects on the reduction of CO2 emissions. The idling stop campaign has been suggested to accomplish this goal because it can decrease the fuel consumption and the exhaust emissions for all conventional gas engine vehicles. To measure the fuel consumption effect of short-time idling stops with the traffic signal, a comparative study has been conducted using two 1498 cc gas engine vehicles and their road performance has been analyzed. Based on our analyses, we have formulated the following equation that can predict the amount of fuel saved when the idling stop campaign is exercised:Fs=I× (∑Tis)-S2× (Nis)where Fs (cc): Saved fuel consumption, I (cc/s): Idling fuel consumption, Tis (s): Idling Stop period, S2 (cc): Additional fuel consumption by restarting, Nis: Idling stop times.Also we have proposed a new evaluation parameter, i.e., limited effecting idling stop time (LEIST) and used it as an index for the maximum efficiency duration of idling stop.Our performance test showed I=0.17 (cc/s) and S2=1.2 (cc), which indicated the tested vehicles LEIST was 7.0 seconds, a close approximation of the result obtained in our experiment.

Measurement of quenching distance by a burner.

The flame at the top of a burner enters into the burner channel by stopping a mixture quickly. The quenching distance measured by a burner method means the minimum width of the channel through which the flame can pass. The problems about three measurement methods are discussed with optical observation in this paper, and it is found that a tapering burner method is the most recommendable among their method : it is due to the following reasons. When the mixture is not spark-ignited but the flame is held at the top of the burner, the initial condition of the flame is not steady. In a parallel burner method with speak ignition, abrupt change of cross-sectional area of the flame entrance often prevents the flame from entering the channel. At that time, the flame does not interact with the surface of the channel. The above defects are omitted in the tapering burner method with spark ignition.

A fundamental study of quenching distance measured by the flanged electrode method (Selection of ignition energy and diameter of flanged disk)

Flanged electrodes need to have two functions to determine the value of quenching distance with accuracy: The first function of flanged electrode is to start flame propagation at the centre of the disk. The second is to stop and quench the flame by the disks. These functions are quite dependent on the ignition energy and the diameter of the flanged disk. The experimental results confirm that the value of quenching distance is essentially independent of the ignition energy but the recommendable value of ignition energy is two or three times that of minimum ignition energy, and the measuring limit of the quenching distance linearly extends with the diameter of the disk.