Our previous report clarified the curvature effects on cavitation characteristics for right-angled branch ducts having corner radii of R/b=0, 0.25, 0.5 and 1.0, where R was the radius of the curvature and b was the width of the duct. The loss coefficient in branch side ξ₁₃ was almost constant for R/b=0, 0.5 and 1.0, while ξ₁₃ was not constant, but unexpectedly showed an abnormal change with respect to cavitation number σ₁ for R/b=0.25. The purpose of this paper is to clarify such an abnormal change. Therefore, the present experiments wee conducted by changing R/b around 0.25 as 0.1, 0.2, 0.3 and 0.4. This abnormal phenomenon was observed in wide ranges of the curvature and the flow ratio, especially at a flow ratio K=1.0 and R/b=0.2. As a result, it is concluded that this phenomenon is principally related to the effect of fluid viscosity, not to cavitation.

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The motion of a spark-induced cavitation bubble was examined near a solid boundary by high-speed photography and the impulsive pressure generated at its collapsing stage was detected by a local pressure sensor, which was manufactured for trial with four small sensor elements. As a result the impulsive pressures of a shock wave and of a water microjet were separately measured by the local pressure sensor, and the results was ascertained by high-speed photographs of the cavitation bubble, which indicated a microjet was generated at the top surface of the collapsing bubble, impacting one of the pressure sensor elements through the bubble inside at its collapsing stage. Moreover, the diameter of the generated microjet tip and its travelling velocity through the bubble inside were evaluated to be about 0.5 mm and 100110 m/s, respectively.

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Characteristics of both the thin liquid and the high speed gas layers in a separated flow were experimentally investigated. The result shows that liquid film with a film Reynolds number less than 170 moves, at least near the gas-liquid interface, with a velocity much higher than that obtained by assuming a laminar liquid film flow. The equivalent sand roughness of the liquid film surface increase with the gas velocity even when waves are inside a viscous sublayer of the gas flow. This is because the normal component of the gas velocity need not be zero at the gas-liquid interface. Due to this velocity fluctuation the gas particle with a higher velocity can penetrate into the liquid film; then the energy loss in the gas phase becomes large while the liquid velocity at the inter face can be much higher than that of a laminar liquid film flow. As a result, it is concluded that even a thin liquid layer with a small Reynolds number can not be assumed laminar when it is forced to flow by a high speed gas flow.

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This paper describes an experimental study on the locations and structures of pseudo-shock waves in straight ducts with rectangular cross sections when the flows are choked at the duct exits. The ranges of experiments were 1.72≦M_∞≦1.85 and 20.6≦L/D≦23.6, where M_∞ is the Mach number at the duct entrance L the length of the duct and D(=50mm) the width of the duct. It is shown that the location of pseudo-shock waves moves in a downstream direction with decreasing L/D and increasing M_∞. As the location of pseudo-shock waves moves in a downstream direction, the shape of the pseudo-shock waves changes from λ-type to X-type because of the increase of wall turbulent boundary layer thickness. It is also shown that the diffusion rate of low speed region near the duct wall in a pseudo-shock wave becomes smaller as the location of pseudo-shock wave moves in a downstream direction.

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Nitrogen gas is set to spurt from a small circular hole located at the end wall of a shock tube at about 35 ms before the shock wave arrives and reflects there. Interacting with the jet the reflected shock wave changes its shape from a plane shock wave to a curved one. We observed the phenomenon by the use of a schlieren system, time counters and pressure gauges. We calculated the pressure and the temperature behind the curved reflected shock wave by the use of its distance-time relations, the differentiation of cubic natural smoothing spline functions, and Rankine-Hugoniot equations. In this paper, we want to prove that the method, which we proposed in the previous work, is a reasonable and available one. The results are as follows: (1) From pressure profiles, we could show that the proposed method was a reasonable and available one. (2) When an unstable, curved, reflected shock wave turns back to a stable plane shock wave, it generates some expansion waves, which cause a temporary pressure-drop (about 120 μs) in the Kistler transducer on the side wall after the passing of a reflected shock wave. (3) The calculated results using the proposed method are supported by the experimental facts of (2), and the facts show that a strong inverse flow is made by the interaction between the reflected shock wave and jet behind the reflected shock wave.

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The four stage Runge-Kutta(4SRK) and two stage Rational Runge-Kutta(2SRRK) schemes have been applied to solve the compressible Navier-Stokes equations, in order to develop a fast, accurate, explicit time-marching technique suitable for vectorization. On a supercomputer, a problem of shock-boundary layer interaction is calculated by use of these schemes combined with local time-stepping. It is shown that the 4SRK scheme with the fourth-order central differencing of convective terms is stable out to a Courant number of 2.06 according to Neumann's stability criterion. The practical limit of Courant number has been very close to the theoretical limit. At a high Reynolds number, the Courant number limit of 2SRRK scheme is significantly less than that of conventional explicit methods. Both the 4SRK and 2SRRK schemes are readily vectorizable. The use of implicit residual averaging reduces iterations, but is not suitable for vectorization.

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A panel method was applied to transonic flow problems of obtaining shock-free airfoils in turbomachine cascades. With introduction of Sovieczky's fictitious gas concept, the panel method succeeded in treating both subsonic and supersonic flow regions in a unified fashion. It was shown that the location of a sonic line was not necessary for the formulation of the panel method. In the process of calculation the sonic line was determined automatically under given fictitious gas conditions. But the supersonic flow region thus obtained was recalculated to meet the actual gas conditions and to find out how much modification of the airfoil shape was required. At higher Mach numbers a limit line was often encountered, and valid shock-free solutions were destroyed. Numerical results show that the shock-free solutions are obtainable even at higher Mach numbers under such conditions as follows: high inlet flow angles, high pitch-chord ratio, and rear-loaded airfoil shapes.

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The forces generated by water-square cylinder interaction have been investigated experimentally. Three kinds of square cylinder models of 50 mm, 75 mm and 100 mm width were used. The square cylinder with two endplates was oscillated horizontally in standing water by mechanical oscillation machinery. The force was measured by means of a quartz force transducer. Period parameters ranging from 0.2 to 1.8 and Reynolds numbers from 450 to 51460 were covered in the investigation. The results have shown that the wave forms of the forces depend on period parameters and Reynolds numbers, and the force amplitude coefficients are determined only by period parameters.

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In the foregoing paper, the characteristics of the time-mean and fluctuating forces acting on two rectangular prisms in tandem arrangement placed vertically in a turbulent boundary layer were described. As a continuation of the foregoing paper, the behavior of the aerodynamic forces of two prisms in side by side arrangement were investigated experimentally. The results were summarized in several figures from which one can obtain the time-mean drag and lift, the fluctuating drag and lift, and the Strouhal number for the various spacing between the two prisms. Further, they variation of the flow pattern with the spacing between the two prisms were discussed in detail based on the variation of Strouhal number, and cross correlation between the fluctuating pressure acting on the two prisms. In particular, it was found that the variation of the Strouhal number with the spacing between the two prisms can be classified into four regions.

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The structure of large-scale vortices behind a thin flat plate being rotated in a uniform stream around its axis with a constant angular velocity is described experimentally by a flow-visualization technique and a phase-averaging technique. The time-mean velocity, turbulent energies and Reynolds shear stresses are also obtained. These measurements are made with 712 plate widths downstream of the centre of the plate; this region was termed as the intermediate wake. Using the phase of rotation of the plate as a reference signal, phase-averaging is made with a minimal dispersion because the large-scale vortices in the intermediate wake were well locked to the rotation. Results are presented for a Reynolds number of 1.25 × 10⁴ and for spin parameters of S=0.28±0.003 and 0.51±0.004. The structure and motion of the large-scale vortices are demonstrated in terms of the vorticity contours in a space-time (or space-phase) domain. a wide region of the negative turbulent-energy production is found in the wake.

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Laminar flows through curved rectangular channels were visualized at the entrance region by using incense smoke. The channels have the aspect rations 1 and 2, curvature ratios ranging from 5 to 8 and a width of 20 mm. Visualization was carried out at 12 positions from the inlet (θ=0°) to the outlet (θ=270°) of the curved rectangular channels. It was clarified that (1) the flow patterns were made by superimposing a constant velocity distribution of main flow and main secondary flow vortices. (2) the main secondary flow vortices were at both sides near the inner wall. (3) two pairs of the new type secondary flow vortices were set up at the position of θ=120° in the case of the aspect ratio of 2 and (4) the maximum velocity point of the main flow was shifted outward from the center and shifted again toward the center as the curved angle θ increased.

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This paper is concerned with the laminar-turbulent transition of three-dimensional boundary layers on cones rotating in external axial flow. The experiment was carried out for three total included cone angles of 15°, 30° and 60° in a range of freestream turbulence (0.04% to 3.5%) using a hot-wire anemometer and a flow-visualization technique. The transition region is determined with the critical Reynolds number and the transition Reynolds number in relation to the rotational speed ratio. The spiral vortices are found to fix relative to the rotating surface. The relation of the direction of the spiral vortices to the rotational speed ratio remains unchanged as the cone angle becomes larger, while the number of the vortices increases with increased cone angle. These experimental results are compared with the present numerical results based on the linear stability theory. The freestream turbulence has no effect on the transition Reynolds number, while the effect becomes more sensitive to the critical Reynolds number as the cone angle is increased.

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Fluid-dynamic forces on a rotating circular cylinder in a uniform flow were obtained by numerically solving the vorticity transport equation. the ranges of calculation are from 20 to 100 for the Reynolds number, R_e, and from 0 to 2 for the specific rotating speed, |V₀|, the ratio of the peripheral speed of the cylinder to the uniform velocity. The results of calculation show that the temporal-mean lift coefficient is nearly independent of R_e and is proportional |V₀|. On the other hand, the temporal-mean pressure drag coefficient increases proportionately to V₀² and that increment is due to induced drag in two-dimensional flow, while the skin-friction drag is independent of V₀. The amplitude of the temporally fluctuating lift coefficient is maximum at |V₀|&elDot;0.5 which is larger when R_e is larger. The amplitude and frequency seem to be strongly affected by the width of the formation region.

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The numerical method based on the algorism of the highly simplified MAC method presented in former reports is applied to the peristaltic motion of power law fluid. The calculation model is a two-dimensional pumping duct of a finite train of peristaltic waves, and unsteady peristaltic motions of power law fluid are calculated in a fixed frame. Calculation is stable over a wide range of exponents and Reynolds numbers. Calculated results of pumping characteristics in the case of small amplitude and long waves are compared with the experimental results of a 1% aqueous solution of CMCNa in a quasi-two-dimensional duct.

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The acting shear stress and pressure on the vascular wall are considered as being a source of vascular lession, and are investigated numerically from the hydrodynamic point of view. As a model of the blood flow in an artery with a rough surface, the rigid channel with roughness elements in the wall is considered, and blood is assumed to be Newtonian fluid. Using this model, the Navier-Stokes's momentum equation and the equation of continuity are solved by the finite difference method. The calculation is performed for the Reynolds numbers of 50, 100, 200, 400, 800, 1000 and 2000. And the shear stress at the wall, the stream lines and the equi-vorticity lines are presented.

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The blood flow in an artery with a rough surface is investigated numerically. As a two-dimensional model of the blood flow in an artery with a rough surface, the pulsatile flow in the rigid channel with roughness elements in the wall is considered, and blood is assumed to be a Newtonian fluid. Using this model, the Navier-Stokes's momentum equation and the equation of continuity are solved by the finite difference method. The calculation is performed for the Reynolds number of 300, 600, 1200 and 2000. but the period and amplitude of oscillation are fixed. The shearing stress variation on the wall of roughness elements and the stream lines are presented. The shearing stress at some points of the roughness element are Fourier analised, and the results are shown.

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An experimental and theoretical study is presented for the interfacial instability of magnetic fluids in rectangular containers subject to magnetic fields. Experiments were performed to determine the critical field intensity for incipient instability and to observe the growth of instability waves. Magnetic fluids used in the experiments were waterbase ferricolloid W-35 and its dilution with distilled water. It was found that interfacial instability appeared when the field intensity exceeded the threshold value and grew in amplitude with the field intensity. It was also found that the wave number for the instability depended upon the field intensity and the dimensions of the container. The possible equilibrium configuration was analyzed theoretically by minimizing the total energy. The experimental results can be explained well by the theoretical analysis.

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Study of the rheological property of water, hydrocarbon and diester based magnetic fluids is done with and without magnetic field. Experimental study is made using the concentric cylinder type rotating viscometer which is operated within the strong magnetic field to clarify the effects of magnetic field, temperature and shear rate on thee rheological characteristics of the magnetic fluids. The above magnetic fluids are Newtonian in the case of no magnetic field. In the case of applied magnetic field, the observed flow curve for hydrocarbon based fluid is still Newtonian. On the otherhand, the water based and diester based fluids show pesudoplastic behaviour. Empirical formulae based on the theoretical consideration of the laminar flow between rotating concentric cylinders are obtained.

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This paper describes some experimental values of flow resistance for wire nettings in low Reynolds number flows, such as air natural convections, providing basic thermal data necessary for designing electronic equipment casings. The experiment was designed to evaluate resistance coefficients, depending on the air temperature increased by the combined effect of motive powers for natural convection and flow resistance for wire nettings, because measurements for pressure losses and velocities in low Reynolds number flows using conventional methods are very difficult. As a result, the following relationship was obtained from a practical point of view: K=28(R<ed>·β²/1-β)^-0.95, 0.4<R_ed<95 where K is the resistance coefficient. R_ed is Reynolds number based on the wire diameter and β is porosity coefficient for wire nettings.

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The staggered arrangement of two circular cylinders is likely to occur very often in engineering aplication. In a previous paper, it has been reported that, even for the small oscillating amplitude of an upstream cylinder, the time-mean flow around the downstream cylinder was greatly affected in some particular arrangements. The present study is concerned with the effects of the fluctuating fluid forces and the fluctuating pressure acting on the downstream cylinder. Measurements are mainly made on the r.s. m. values of the surface-pressure fluctuation and the fluctuating fluid forces of the downstream cylinder.

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Fluctuating fluid forces acting on two square prisms of the same dimension in tandem arrangement under small free-stream turbulence (√(u'²)/U₀=1.4%) were studied experimentally. Measurements of the fluid forces and the Strouhal number for the spacing ratio between tow prisms s/w (s: spacing between two prisms, w: width of prism) up to 10 yielded the following results: (i) Jump phenomenon which appears at s/w=3 in a smooth free-stream appears in the region 2.1&lE;s/w&lE;3.0 and the flow pattern becomes unstable when small turbulence is introduced in the free-stream. (ii) A method of obtaining the fluid forces in the jump-flow region where two flow patterns appear intermittently was introduced. (iii) Under a small turbulence in the free-stream, both the fluid forces and Strouhal number were found to change considerably compared to those of smooth free-stream. (iv) Distribution of the Strouhal number with s/w was classified into four regions, and the characteristics of the vortex pattern for each region were clarified.

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The basic theory of singular perturbation method on steady jet curtain problem in inviscid and incompressible fluid flow constructed in the 1st report is applied to the interference problem; the floating sheet is very thin and flexible, and its deformation is determined by the spacial pressure due to the jet curtain. In the present paper, it is shown that the floating system is constructed mainly by three fundamental interference problems, and essential inner and outer solutions are obtained. Moreover, three typical cases are analyzed by using the above essential solutions, and the relation between the deformation of the thin sheet and the cushion pressure is obtained.

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The casing boundary layer flows behind an isolated axial compressor rotor with various tip clearances were measured under design and off-design conditions. The velocity distributions inside the boundary layer, measured by a slow-response 5-hole pressure probe, are closely related to the phase-locked flow pattern of a leakage vortex measured by a fast-response slanted hot-wire. As the vortex is stronger, the local efficiency of a blade element becomes higher near the casing wall, and becomes lower at the inner side of the vortex center. The integral parameters of the casing boundary layer were calculated to clarify the effect of the tip clearance on the boundary layer development. blade-tip efficiency is introduced by use of these parameters. There is no significant difference in the variation of the blade-tip efficiency with tip clearance between the design and the off-design condition, except an incipient stall condition.

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In this paper the velocity and the pressure distributions within the scroll of multi-blade blowers are studied. The blockage factor used for performance calculation is obtained experimentaly. It is shown that the meridian velocity c_m2 at the outlet of the impeller is nonuniform in the axial direction and peripheral direction. The blockage factor is defined by taking the non-uniformity of c_m2 into account, and has a minimum value of 0.38 at the width-diameter ratio b₂/D₂ of 0.4, and has a tendency to increase with decreasing b₂/D₂. The influence of the inlet diameter to the outlet diameter ratio D₁/D₂ and the capacity coefficient ψ on the blockage factor is small.

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A panel method of obtaining accurate three-dimensional incompressible potential flow in a centrifugal impeller is presented. The basic equation is the surface integral representation for velocity potential based on Green's identity, which reduces to a set of linear equations by discretization procedure. Numerical calculations are performed at flow rates 100% and 75% for an impeller designed by the conventional method. The one-dimensional flow obtained by a simple one-dimensional theory, a two-dimensional calculation and the present three-dimensional one are compared to clarify the degree of approximation of each flow. The three-dimensional characteristics are investigated examining the pressure distribution along the blade elements on the hub, mid and shroud stream surfaces, the pressure contour and the relative velocity vector on the pressure and suction surfaces of the blade, the head distribution at the impeller outlet surface, and so on.

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A test apparatus of turbine scroll has been devised to investigate the secondary flow phenomena in a scroll. The scroll is of parallel end wall type and based on a logarithmic spiral. The three-dimensional flow field survey can be taken in arbitrary cross sections with a probe traverse mechanism newly developed. Distributions of total pressure and three velocity components have been measured in detail, using a five-hole probe. The secondary flow field is to be dominated by passage vortices on end walls and low energy fluid accumulating on a tongue. The favorable pressure gradient and the inward secondary flow on end walls suppress an extreme growth of wall boundary layer. However, the secondary flow affects the distribution of exit flow angle in the direction of passage height.

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A seriously fouled condenser of the Sakai-Port Power Station which started in 1965 has been renovated by in-situ artificial protective film (APF) coating of the condenser tubes. The condenser of the No.2 unit with a capacity of 250 MW has two-water boxes called "A" and "B" condensers installed with aluminum -brass tube. The gradual decrease in heat transfer performance of the condenser tubes has been revealed by inspections of removed tubes. Based on measurements carried out in October 1983 for evaluating in-situ APF coating, in march 1984 in-situ APF coating was applied to only A condenser being more heavily fouled than B condenser. The comparative measurement conducted in October 1984 proved that the condenser vacuum was improved by about 0.6 kPa. The removed APF coated tubes presented sound coated surfaces, except for some tiny blisters at both ends, and no indication of corrosion after six months duration. In-situ APF coating is concluded as being a good countermeasure against corrosion and fouling.

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For predicting the fully developed upward flow in a uniformly heated vertical pipe by taking account of the buoyancy force, the k-ε models of turbulence for low Reynolds number flows were adopted. The regime map for forced, mixed and natural convections as well as for laminar and turbulent flows was plotted from the numerical calculations. At the same time, an experiment was carried out at Reynolds numbers of 3000 and 5000 with the Grashof number varied over a wide range by using pressurized nitrogen gas as a test fluid. In agreement with the prediction, buoyancy-induced impairment of heat transfer was measured right in the mixed convection region. Further, from hot-wire measurement, complete laminarization was demonstrated in the mixed convection region at a Reynolds number of 3000.

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Numerical analysis is conduced on the forced convection heat transfer in rectangular ducts with aspect ratios 0.2, 0.5, 2.0 and 5, 0, rotating at a constant angular velocity about an axis perpendicular to its axis. Navier-Stokes and energy equations are solved by a finite-difference method in the fully developed region of laminar flow. Velocity and temperature fields are obtained for various rotation rates and Reynolds numbers at each aspect ratio of the duct. A double-vortex secondary flow appears at low to moderate rotation rates. An additional pair of vortices appeared and disappeared for a higher range of Reynolds numbers due to aspect ratios of the ducts. The friction factor and Nusselt number are influenced by the Coriolis force and aspect ratio. Numerical results of the friction factor for aspect ratios equal to 0.5 and 2.0 are in good agreement with experimental results by other researchers.

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A numerical analysis is presented for the fluid motion and heat transfer in the tank of a Coal Oil Mixture [COM] carrier ship rolling in a wavy sea. A non-Newtonian fluid model is adopted to describe the flow behavior of the COM. The motion of the tank is assumed to be a simple harmonic rolling motion, and similarity parameters for the fluid motion and the heat transfer are given. The flow velocity and temperature distribution in the tank is determined by a numerical solution of the basic equations describing the flows in a tank with rolling motion. Heat flows from the tank walls and the shear stress in the tank are predicted when a ship is rolling in waves. The influence of the frequency of the rolling motion on the heat transfer rate is also examined.

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This experimental study has been conducted on the free convection from horizontal cylinders, vertically lined in array, set in a vertical duct or in free space. It has been found that the Nusselt numbers for each cylinder in an array are proportional to the 1/4 th power of Rayleigh number in both case, and the experimental data concerning the average Nusselt number for the whole array can be well represented by a practical formula. Eq. (2.a), which covers the cylinder arrays set either in free space or in a vertical duct.

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This paper is concerned with the melting of a horizontal ice layer from above by an aqua-solvent with a low solidification point. The solutes used in this experiment are Calcium Chloride and Urea. The upper surface of the melt layer is heated by radiative energy. The ice layer located under the melt layer of the aqua-solvent melts greatly by a combined effect of both thermal energy and chemical reaction, and the typical temperature distribution in both the melt layer and the ice layer is examined. The relation between the melt amount of the ice layer per unit temperature gradient and the mean concentration in the melt layer of aqua-solvent was obtained.

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The renewable energy laboratory of the Kitami Institute of Technology is a facility for thee research of space heating, cooling and hot water supply by means of solar and underground water energies using a solar system and a heat pump. The experiment at the first hall started in 1982 and the second hall has been used since 1983. The measurements for two combination types of series and parallel solar-heat pump systems were carried out for two periods between Nov. 21 st 1984 to Feb. 20 th 1985 respectively. comparing the two combination types using a system C. O. P., the performance of the parallel combination of the solar-heat pump system was better than that of the series combination. Besides, several analyses of the solar-heat pump system were done for prediction of the system performance.

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To analyze the thermal efficiency of the complicated power generation system such as a coal gasificated combined cycle power plant, it is necessary to prove differences of system components. This paper a simple coal gasification equation based on an equivalent coal composition C₁₈H_hO₀ is proposed. And a thermal efficency analysis method with a net thermal flow chart is described in which each component is represented by several parameters. With the use of this method, it is possible to indicate an essential thermal flow and to indicate an essential thermal flow and to show an influence of differences of system components evidently.

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To raise the thermal efficiency of the complicated power generation system such as a coal gasificated combined cycle power plant, it is necessary to analyze the irreversible changes in the processes which cause heat losses. In this paper a new method of adding an exergy analysis method to the thermal efficiency analysis method treated in the previous paper is described. With the use of this new method, the useless exergy decreases caused by gasification reaction, heat transfer, etc., are evaluated and the results are represented in the form of an exergy-anergy flow chart. By means of the abovementioned series of analyses, it has been proved to acquire information of improving thermal efficiency.

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The present paper deals with the flame development after the still mixture in a box-type chamber was ignited and examines the method of analysis for estimating correctly the heat transfer rate from the gas to the wall. Calculated pressures and flame developing patterns in a box of simple shape and that of a complex shape with a block have been compared with the measured results. This comparison has revealed that the present method gives a precise estimation, unless there is no generation of strong secondary flow and turbulence as a result of flame growth; and that the assumption of spherical flame development should be discarded because the flame, even if it develops in a simple box, begins to change its form into the shape of the vessel early; about a third of the burn-up time.

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If a gasoline engine can be run with a lean air-fuel mixture, a considerable improvement is expected in fuel consumption and in exhaust emissions. Especially in the case of automobile use, this effect is remarkable because of a peculiarity in the high frequency usage of engines operating under a partial load. Therefore, investigation of lean air-^fuel ratio combustion has been put foward zealously. But it seems to have been concentrated on aspects of hardware improvements such as the shape of a combustion chamber, the configuration of an intake manifold, etc. This study was attempted under these circumstances as a software approach. It means a real time optimalization control of an air-fuel ratio with the object of maximum indicated thermal efficiency by using an on-line digital computer. as a result of the control operations, an expected improvement was attained.

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In this study, the cold startability and the blue and white smoke (cold smoke) in a direct injection diesel engine when changing the intake swirl and the combustion chamber shape have been investigated. In the shallow bowl and square cavity combustion chamber, the intake swirl does not have so large an influence on the startability; but in the deep type, the starting time becomes longer by increasing the intake swirl, and the cold smoke rises higher. It was found that the intake swirl was not necessary for starting and warming-up under cold conditions.

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An experimental study on the reforming characteristics of five different catalysts for methanol fuel was conducted and the endurance of each catalyst was examined using a fixed type reformer. A reformer utilizing the heat of exhaust gas was also designed and constructed, and the effect of blending the reformed methanol fuel to gasoline was studied in the combustion process of a spark ignition engine. Analyses of the indicator diagram show that the increase of the ratio of reformed gas and gasoline results in (1) an increase of speed and stability of combustion characteristics, (2)the extension of the lean limit of the air-fuel ratio, (3) an increase in the thermal efficiency, (4) a decrease in the cycle-by-cycle fluctuation of the combustion process, and (5) quick achievement of stability for abrupt changes in the throttle position. In view of three results, the optimum operating conditions are proposed.

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This paper gives experimental results obtained with a two stroke cycle single cylinder research engine using an electrically heated combustion chamber to simulate the combustion chamber of a low heat rejection DI diesel engine with an M-combustion system. It is concluded that the combustion characteristics of an M-combustion system are greatly affected by surface temperature and the indicated thermal efficiency is significantly improved at higher surface temperatures.

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