Hideaki Tanabe

Experimental Study On Transient Gas Jet

This paper presents the experimental study on the characteristics of a transient gas jet. Helium was injected instantaneously into a quiescent atmosphere with constant pressure. The distributions of instantaneous static pressure, radial and axial velocities and concentration at measuring points in the jet, which is obtained by the statistical data processing, are discussed to explain a transient mixture formation in the jet. The analogy between this jet and a diesel spray as for this mixture formation are also discussed by using these results.

Experimental study on unsteady gas jet

In order to clarify the mixture formation process of the direct injection gas engine, helium gas was injected into a quiescent atmosphere. The time- and space-resolved velocity, pressure and concentration distributions were measured in the free unsteady gas jet and in the wall impinging unsteady gas jet. They were also obtained for the unsteady gas jet impinging onto a projection on a wall to enhance mixture formation. Empirical equations for the unsteady free jet were obtained, and the mixture formation mechanism of the wall impinging unsteady gas jet were clarified. The unsteady gas jet impinging onto the projection on a wall entrains much more air than the unsteady wall impinging jet. 8 refs., 20 figs.

Effect of Cooling Water Temperature on Particulate Emission from Diesel Engine

In order to clarify the effect of cooling water temperature on particulate emissions, a single cylinder engine was used for engine test at various cooling water temperature under various engine load.From the experiment, lower cooling water temperature increased Soluble Organic Fractions (SOF) remarkably, which results in total particulate increment. Dry soot, on the other hand, was little affected by cooling water temperature. Total Hydrocarbon (THC) also increased as the cooling water temperature decreased.These results indicate that the wall quenching plays an important role on SOF formation as well as THC formation.

Movement of Surroundings around a Diesel Spray

Diesel spray injected into an atmosphere with high pressure and high temperature becomes, within a few milliseconds, a transient two-phase flow, entraining the surroundings. The motion of the surroundings is a significant phenomenon for the mixing of droplets and the entrained surroundings, and this phenomenon determines the combustion processes of diesel spray. In the experiment presented here, motion was visualized by the smoke-wire method. Moreover, the movement around a two-dimensional steady water spray (two-phase flow), and an unsteady water jet (single-phase flow), were also tested to generlize motion in the surroundings of the diesel spray. It was found that the entranining angle, the coefficient of entrainment velocity, and the entrainment coefficient of diesel spray at penetration part (where it shows characteristics of steady flow) are similar to those of two-dimensional steady water spray and the unsteady water jet, and that the ratio of the volume of the entrainment to the total volume of either the spray or the jet is nearly equal to 0.5.

Study on Unsteady Gas Jet

In the Gas Injection Diesel Engine (GIDE), the mixture formation process between the injected fuel gas and air plays an important role on combustion and consequently on the engine performance. This paper deals with the characteristics of a transient gas jet as a fundamental study of the fuel gas jet in the GIDE. Helium was injected instantaneously into a quiescent atmosphere with constant injection pressure. The instantaneous distribution of static pressure, velocity and concentration in the jet, which is obtained through the statistical data processing, are discussed to express a transient mixure formation process in the jet. Results are also applied to discuss the ignition and combustion phenomena in the GIDE.