In order to clarify three dimensional velocity fields at rotor outlet with vortex in a semi-opened propeller fan, the experimental investigation was carried out using hot-wire anemometer. Tip diameter of test rotor was 310 mm and its rotor had four blades. The front half of blade tip was opened and the rear half was covered with casing. The tip clearance at rear half part is 1mm at constant. As results, it is found that the main stream region at rotor outlet has concentrated on the area between mid-span and blade tip and the dead flow region is formed on hub as flowrate decreases. It is also found that the vortex exists in the flow field of rotor outlet and its vortex moves toward the pressure surface of next blade with decreasing flowrate.

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In the wake-rotor interaction fan noise, the interacting modes at the Blade Passing Frequency（BPF）and its harmonics are generated which are prescribed by the number of stator and rotor blades etc. In the present study, the dominant mode is tried to be suppressed by the secondary spinning sound waves from the loudspeaker actuators. The experiments are conducted under the conditions of three rotational speeds of 2,000, 3,000（or 2,700），and 4,000 min^-1. Using the control system with 12 loudspeakers, for a target of a single mode at the BPF, a good reduction in the Sound Pressure Level（SPL）is observed for all three rotational speeds in experiments. For a target of a mode at the 2nd BPF, however, a reduction in the SPL is poor.

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There is a pulsating flow in reciprocating pumps generally to do a sign curve movement of the form. Multiplex type pulsation-free pump needs special cam form for avoiding the pulsating flow. However, a micro pulsation occurs in the start part of section of piling the flux wave form of two reciprocating pumps. The cause of this pulsation is analyzed in the present paper. And the way of amending the cam, which is necessary for eliminating the micro pulsation, is proposed and the applied result is described.

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The rotating stall cell of a multiblade fan is formed in the vicinity of the front side of the impeller without shroud （MF9）. In this experiment, the cell of MF9 rotated at approximately 40％ rotation speed of the impeller. The pseudo blades due to the cell are formed around the impeller. The aerodynamic noise source is distributed uniformly at the vicinity of the front side of the impeller with shroud（MF9S）because the cell is hard to be formed by the shroud. Accordingly, the broadband noise of MF9S in the low frequency domain became large than that of the MF9 at the vicinity of the rotation speed of the cell. Since the pressure characteristic of MF9S becomes high than the MF9, the overall characteristics of MF9S, that is, the specific noise level is improved at the high flow rate domain than the maximum efficiency point.

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Unsteady cavitating flows around two types of isolated two-dimensional hydrofoils, flat plate and Clark-Y 11.7％, are　experimentally studied in order to understand the unsteady characteristics of cavitation instabilities. From visual observations　using high-speed video cameras, the cavity length fluctuations with the cloud cavity formation from the trailing edge　of attached cavity are investigated as well as cavity patterns such as patch, sheet（partial and super），shear, and so on. The　pressure fluctuations near the leading and trailing edges of hydrofoil are measured simultaneously with high-speed camera　recording, to relate the emitted pressure disturbances with sheet cavity fluctuations. It is found that, despite of large geometric differences between hydrofoils, two types of cavitation instabilities, partial and transitional cavity oscillations, can occur for both hydrofoils, provided the necessary flow conditions：the partial cavity oscillation occurs when the partial cavity forms from near the leading edge of hydrofoil. The transitional cavity oscillation is unaffected by the location of the leading edge of the cavity, and occurs when the trailing edge of the cavity becomes close to that of hydrofoil.

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