We attempt to simulate several actual cavitating states appearing in the vibrating field through indirect vibratory erosion tests, whose vibratory system conforms to the ASTM Standards. The cavitation aspects and the distributions of cavitation-induced pressures are systematically observed for various distances L between the stationary specimen and the horn-tip surface, under a specified condition of cavitation-nuclei size distributions. With respect to the distance L, the cavitation aspects and the corresponding pressure distributions are systematically changed from the subcavitating states to the supercavitating states, as in ordinary cavitating flow.

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It is known that low cycle system oscillation tends to occur in a piping system connected to a high-speed pump in which cavitation is occurring. The majority of papers on this subject discuss attempts at predicting this occurrence through linear transfer matrices of cavitating pumps, both experimentally and theoretically. There are, however, few papers that discuss low-cycle system oscillation occurring in reverse flow at a pump inlet. The following discusses three types of low-cycle system oscillation, which are defined by synthetic studies. The effects of NPSH, pump flow rate, rotational speed, and pipe length are clarified experimentally.

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In flow simulations performed with the finite difference method or the finite volume method, it is a serious limitation that the calculating points must be ordered on the coordinates. Using the Voronoi diagram for the cell division of the finite volume method creates a new discretization form which permits an arbitrary distribution of points. This paper constructs a new method for the flow simulations by a Voronoi diagram and shows the calculation results of two-dimensional flows.

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The instability of a vortex ring is investigated numerically by a three-dimensional vortex method. Disturbances with small amplitude are imposed initially over a local region of a vortex ring, and the development of large-scale instability waves and/or small-scale irregular motions of vortices along the vortex core is studied. Three different types of disturbances are considered : (1) sinusoidal disturbances with wave number m=6 (hexagonal), (2) random disturbances, and (3) random disturbances superimposed on sinusoidal (m=6) disturbances. It is found that locally imposed sinusoidal disturbances propagate along a vortex core and produce large-scale instability waves over the whole region of a vortex ring. On the other hand, the propagation velocity of locally imposed random disturbances along a vortex core is negligibly small, and the development of small-scale irregular motions of vortices is almost confined within the local region.

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Through the use of scaling arguments, a simple model describing the boundary layer behavior during vortex shedding is proposed. The main focus of the model, which is based on the assumption that the viscous diffusion length is directly proportional to the boundary layer thickness, is set towards predicting the salient features, but not the details, of the periodic flow. Promising results have been achieved upon applying the model to the classical problem of vortex shedding over a solid circular cylinder. It is noted, however, that there is a need for futher scrutiny in terms of a detailed comparison of the predicted results with existing numerical data. The model has also been applied towards investigating the behavior of the vortex shedding or Strouhal frequencies as influenced by boundary layer suction and injection (blowing) occurring normal to the stream. Among the interesting findings dealing with this part of the study, a critical Reynolds number is predicted which acts as the transition from one limiting frequency behavior to another.

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Experimental studies are conducted on a supersonic flow CO chemical laser to obtain data on the reaction zone structure and the small signal gain coefficients when various gas additives are injected at the reactant interface. The additives are Ar, O₂, N₂O and CO. It is shown that the chemiluminescence from the laser cavity and the flow structure do not depend strongly on the kind of injected species, although the injection of gas additives considerably enhances the mixing. On the other hand, the measured small signal gain coefficients depend strongly on the injected species. The injection of O₂ leads to the higher gains than that of Ar since the formation of the vibrationally excited CO molecules is promoted. The injection of N₂O and CO also raises the gains due to the favorable effects of VV transfer.

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The internal flow in a cross-flow turbine is very complicated because the water passes through only a part of the runner. Therefore this type of turbine has been designed and manufactured until now on the basis of Banki's one-dimensional analysis and empirical results. In this report, the flow inside a cross-flow runner is analyzed two dimensionally. The unsteady flow along streamlines in the relative system of the runner is calculated numerically and the flow along the runner periphery is investigated. Additionally, calculated results are compared with experimental data and good agreement between them is demonstrated. Furthermore, it is made clear that the flow inside the runner is exceedingly nonuniform along the runner periphery.

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The discrete vortex method was used to provide detailed information on the flowfield and starting torque on a stationary Savonius rotor. The rotor average starting torque depends on its setting relative to the oncoming wind. The rotor position normal to the wind was selected to examine the local flow properties on and around its buckets. The results obtained were used to explain the relatively low torque developed by the rotor at that position.

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The flow behavior in a disk MHD generator was studied under high MHD interaction conditions. Experiments were conducted using the blow-down facility, and argon seeded with cesium was used. The static pressure distribution, the flow velocity, fluctuations of the static pressure and the swirl were measured. The results show that when load resistance and seed fractions are high, the steep pressure increase appears at the upstream region in the MHD channel owing to the enhanced Lorentz force. On the other hand, the location of the pressure increase shifts downstream with the decrease of the Lorentz force. At the same time, the increment of pressure becomes small. A large fluctuation of the static pressure was observed at the upstream region where the steep pressure increase appeared. Characteristics of the pressure fluctuation are found to be analogous to those of the pseudoshock observed in channels without MHD interactions. Furthermore, it is confirmed that the swirl becomes large with the increase of the Hall current.

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The required thermal conditions for control of thermal stresses during the melt growth of Si, GaAs, InP and CdTe are compared. The results indicate that the low thermal conductivity and CRSS values of the compound semiconductors results in significantly lower values of admissible heat transfer rates in these materials when compared to Si.

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A finite-difference solution algorithm is developed to solve the Navier-Stokes equations in a nonorthogonal curvilinear coordinate system. The governing equations are written in the strong-conservative-law form. A rectangular computational domain is yielded by Moretti's transformation. The tasks of numerically generating the body-fitted coordinate by partial differential equations are avoided. Hence the matrix of the transformation can be determined by direct analytic differentiation. The discretized conservation equations are derived on a control volume basis and solved by the extended SIMPLE calculation procedure. Numerical results obtained by employing the present methodology will be compared with results from analytical solutions. The relative merits of three numerical representations, i.e., power-law, hybrid, and first-order upwind, for approximating the convection terms in the momentum equations are compared. The results show that the numerical results exhibited excellent agreement with the available analytical solution.

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A method using a passive electrostatic probe to detect a flame by its plasma potential signal has been developed. The spatial resolution of the probe in this method is shown to be significantly improved over that of the conventional electrostatic probe. The plasma potential signals obtained by this method from premixed turbulent propagating flames show one to six spikes in each signal ; each spike is considered to be a flamelet in the flame zone. On the basis of this consideration, the propagating speed, the thickness of the flame zone, the number of flamelets in the zone, the separation distance between two adjacent flamelets, etc., of the flame, were obtained. The results of this experiment suggest the existence of "reactant islands" in the turbulent flame zone, and show that the number of flamelets in the zone increases with an increase in the turbulence intensity for the same mixture and/or a decrease in the Damkohler number for mixtures with the same turbulence intensity.

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An experimental study was made of the fundamental aspect of the mixture formation in the combustion chamber of an automotive spark ignition engine with multipoint fuel injection. The mixture formation process during the intake stroke of an engine was simulated by the intermittent injection of gasoline or Freon-113 into the steady flow of dust-free dry air through an intake port. The time histories of the vapor concentration at several locations in the transparent combustion cylinder were determined with the application of the laser Rayleigh scattering. The measured results were expressed in terms of the peak vapor concentration at the location of interest, the period of time between the initiation of the liquid fuel injection and vapor arrival, and the duration for the vapor to be observed over a wide range of injection pressures, injection durations, intake valve temperatures, intake valve lifts and intake air flow rates.

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An experimental study was conducted to determine the time history of fuel vapor concentration in the combustion chamber of an automotive spark ignition engine. Laser Rayleigh scattering was applied for the remote, nonintrusive, point probing of the concentration of fuel vapor in the combustion chamber, which was caused by the timed injection of liquid fuel into an intake port. In order to make the optical diagnostics accessible, the original engine was modified to permit installation of an extended combustion cylinder with three sets of glass windows and an extended piston. The results showed that the vapor concentration increased with reduced air fuel ratio, and with increased engine speed and fuel injection pressure. A maximum occurred as a function of fuel injection timing.

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