The purpose of this study is to develop a flowmeter in which flow indication is not affected by setting angle. Flow rate of fluid is observed by deflection angle of a vane sustained by a helical spring.
The principle of the flowmeter is as follows;
A partition is set in a transparent hollow cylinder, and the swivelling vane is supported at the cylinder center. Fluid flows into a space between the vane and the partition, then flows through clearance between the cylinder and the vane, and finaly flows out from another space between the vane and the partition. A moment is generated on the vane by differential pressure generated from the fluid flow through the clearances. The vane is rotated to a certain angle where the moment balances with reaction moment generated from the mounted helical spring. The experimental results indicatedt hat as expected the characteristics of the testing flowmeter is not affected by setting angle. Flow coefficient i n the flowmeter is almostc onstant over the Reynolds numer ranging from 2.0×10²to10⁴.

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Cylindricacl hokes are widely used as a component of oil hydraulice quipment. s The dynamic characteristics between flowrate and pressure drop across the cylindrical chokes were discussed by the authors from a practical point of view, and they obtained the mathematical model which can represent the high frequency characteristics of the chokes.
In the model, they assumed no pressure recovery at the downstream neighborhood of the choke. However, the oscillatory jetflow from outlet of cylindrical chokes shows very complex behavior which are quite different from the steady jetflow and it is not clarified quantitatively. In order to utilize the chokes as a flowmeter, it is indispensable to discuss the estimation of the dynamics of pressure drop in the downstream jetflow region of cylindrical chokes.
In this research, the dynamic behavior of the jetflow in the downstream region of cylindrical chokes are investigated precisely by making use of flow visualization.

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In this research, t he dynamic behavior of the oscillatory jetflow in the downstream region of cylindrical chokes are analized numerically.
The results are compared with the experimental flow patterns which were obtained by the flow visualization. Further, the numerical results are compared with the measurement of velocity distribution of oscillatory flow in the downstream region of chokes, and the pressure along the downstream wall is discussedp recisely.
These experiments confirmed the validity of the numerical analysis. From the results the appropriate pressure tap position is proposed to measure the choke pressure drop.

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