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This paper reports about experimental investigations of rotordynamic fluid force moments on an open type centrifugal impeller in precessing motion. The results show, at design flow rate, that the fluid force moment becomes destabilizing in the region of negative precession frequency ratio: -0.3

This paper presents the experimental results of rotordynamic forces on an open-type centrifugal impeller in whirling motion. For the whirling open-type impeller, the variation of the tip clearance produces the rotordynamic force. It was found that, [1] destabilizing force occures at small whirling/rotation ratio throughout all of the flow range, and [2] At smaller flow rate the magnitude of the force changes dramatically at a whirling/rotation ratio. The forces estimated from unsteady pressure distribution on the casing and that estimated from the pressure difference across the blades are compared with the measured rotordynamic forces.

The history of mechanical engineering education at the University of Tokyo is surveyed and the trend of evolution in the curricula and their requirement conditions is studied. The survey covers the past 106 years between 1886 and 1991, and ten representative curricula are selected from that period. Courses of each curriculum are classified into seven categories and listed for comparison. The history of curricula indicates that the traditional mechanical engineering curriculum, which features heavy concentration in applied mechanics education, took its present form half a century ago and continued until the mid 1980s. The shift from power-driven machines to information-driven ones required qualitative change in mechanical engineering education, and a new generation of curriculum with the combination of natural and artificial sciences appeared in recent years.

Thin-film formation on a rotating disk during the spin-coating process is analyzed. In the experiments for a solution of PMMA (polymethyl methacrylate) solute and chlorobenzene solvent, the final film thickness of dry film formed on silicon wafers for integrated circuits is measured with an ellipse thickness meter. Also, the transient film thickness during the entire film formation process on a rotating optical glass is measured using a laser displacement meter. A numerical calculation considering heat and mass transfer such as solvent evaporation is performed using a one-dimensional complete model proposed by the authors for each phase of liquid film and adjacent gas phase. Satisfactory agreement is obtained between these numerical and experimental results and the effect of various process parameters, e.g., spinning speed and initial film thickness, is clarified by this study.

An air-water two phase flow recirculating water test tunnel was constructed. This tunnel was designed and constructed to measure the performance of either an isolated hydrofoil or a cascade of hydrofoils under variable two phase condition. Void fraction measuring system using Point Electric Resistivity Probe was also developed. In this paper, the specification and the basic characteristics of the tunnel, such as the distribution of velocity, void fraction and bubble radius at the test section, are reported. As an example of test results, the distribution of void fraction behind an airfoil is shown.

The diffusion of a slightly heated jet issuing from a semi-circular tube into quiescent air along plane wall was studied experimentally. Measurements of instantaneous temperature and three velocity components were made by using a four-element constant-temperature hot-wire probe with digital signal processing. As to time-mean characteristics, the measurements confirm the previous findings that the diffusion in spanwise direction is considerably larger than the one in normal direction in far field. Measurements of turbulence indicate no distinct character in the fluctuations of three velocity components, but it is found that Reynolds stress and turbulent heat flux in spanwise direction are markedly higher than those in normal direction. Three-dimensional mixing-length model is applied to predict Reynolds stress and turbulent heat flux. Though the predicted values in normal direction show good agreement with measurements, the predicted values in spanwise direction are essentially lower than the measured ones.

Incompressible potential flow through a cascade of staggered thin airfoils with steady loading in general, unsteady, in-phase motion is considered. With the assumptions of the Kutta condition and linearized wakes, exact analytical expressions are derived for pressure distribution, lift and moment, using conformal mapping applied to the velocity field. Mean attack angle and parabolic camber are considerd to give steady loading, and then the results are expressed in closed-form as quadratures, and reduce to the well-known relations for thin airfoil theory, as the solidity decreases to zero. Typical results are given in the figures. They should serve as a measure of the accuracy of numerical or approximate solutions, as well as representing in a simple way the effects of steady loading, stagger and solidity on unsteady cascade aerodynamics.

Flow pattern in the rotor of turbomachines changes discontinuously when flow rate decreases beyond a critical limit. Typical examples are seen in reverse flow at the suction flow at the suction of axial and centrifugal impellers, in the reversal of discharge direction of centripetal impellers, etc. The purpose of this study is to find a clue to the criteria which initiate the transition from one pattern to the other. Non-staggered rotor was installed in an annulus between two stators with plane-symmetric configurations, so that the flow condition became perfectly symmetric. The flow pattern took either discharge or recirculation mode according to the geometry of rotor and stator. Transition criteria were discussed based on the measured driving torque and discharge flow.

To take out mechanical power from high pressure oil, an impulse type oil turbine of a construction similar to the Terry steam turbine was developed on the basis of the fundamental experiment and the study of the performance of a test turbine. The turbine mainly consists of a nozzle, a turbine wheel with many deflection grooves and several fixed deflection boxes. Comparing with a positive-displacement type oil moter, the oil turbine has such features as feasibility of high rotational speed, low idling resistance, simple construction etc. As the fundamental experiment, a static test of two-dimensional deflectors was carried out and design data for a deflector with minimum losses were obtained. Based on the data obtained from the above, a test turbine was built, and its performance was measured at different rotational speeds and also at different jet velocities. From this study the limit of performance of an impulse type oil turbine was clarified, and the necessary data for designing an efficient oil turbine were obtained.

Two adjacent rows of blades, which constitute a tandem compressor cascade, interfere aerodynamically with each other, so that the deflection angle and losses are different from those of a system having no interference. In order to calculate the interference effect on cascade performance, a method must be found for calculating the change of flow field due to interference. This paper presents a theoretical method for determining the two-dimensional incompressible potential flow through an arbitrary tandem compressor cascade based on a singularity method. This theory is especially suitable for the case in which the relative position between the two blade rows varies, while the blade profiles and settings remain constant. Results of sample calculation are shown and compared with the corresponding experimental results.

For the calculation of unsteady flow around an airfoil, the following assumptions are usually made: 1) Wake is straight, 2) Shed vorticities move downstream with uniform velocity, 3) Kutta-Joukowski's condition holds at the trailing edge. To estimate the validity of these assumptions, wake pattern of a translatorily oscillating airfoil in a uniform flow was visualized by Schlieren method. Instantaneous wake patterns were photographed at reduced frequency between 1 and 19. Observed wake patterns were classified into three types. The range of reduced frequency and oscillation amplitude for each type was given. Kutta-Joukowski's condition was found to be valid at any test condition in the sense that a dividing stream line detached the airfoil at the trailing edge.