Jin-ichi KITAMURA’s research while affiliated with Toyo University and other places

The purpose of this paper is to present the correct theory of the annular viscometer for gases. The measuring principle of this viscometer has been obtained from the Navier-Stokes equation for a steady flow of a viscous compressible fluid in cylindrical coordinates system. To find approximate solution, it is assumed that the mass velocity profile ρv is a function of the distance from the axis of the annular tube. The limit of the value as the mass flowrate ρQ approaches zero gives the true value η of viscosity.

The capillary viscometer for gases of steady flow type reported here is a device of measuring the viscosities of gases in a steady state. The measuring principle of the present viscometer is based on the previously developed Hagen-Poiseuille's law for gases. The viscosities can be obtained by a constant flowrate of a liquid and the pressure difference of both ends. The outlet of the capillary tube is open to atmosphere. This simple trial viscometer enables us to measure the viscosities of gases easily. Experimental results show that the obtained values are in good accordance with known reasonable values.

The velocity distribution at the inlet of a capillary viscometer is determined by the flow before the viscometer. Therefore, this flow is considered to affect the measurements of viscosity by the capillary viscometer. By the theoretical considerations applying Bernoulli's theorem and Newton's law of motion to the flow, the effect is indicated as πa²Δp and let MA be the momentum flowrate at the inlet of the capillary tube, it is known as MA>πa²Δp>1/2MA.

The purpose of this work is to make an attempt to clarify the so-called end correction of a capillary viscometer on the foundation of the theory reported in a previous paper, and to formulate the relation between the measured quantities and viscosity. Some experiments were carried out by using two capillary tubes, short and long, with equal diameters. It is observed that the experimental results agree fairly well with the theoretical con-siderations.

With a usual hot wire anemometer, air velocity is determined by utilizing the relation between the electric current, the temperature of a single heated resistance thermometer wire and air velocity. And the effect of the temperature of air to be measured is considerably large. Therefore it is necessary to heat the resistance thermometer wire to a tolerably high temperature. The double hot wire type anemometer, here reported, utilizes the relation between the electric current, the temperature rises of the double wires and air velocity in order to determine the air velocity. That is, instead of a single wire, double resistance thermometer wires are placed in air flow and the difference of the temperature rises between the two wires is utilized. Experimental results show that the effect of the air temperature is extremely small, and it is known that the air velocity can be measured with small temperature rises.

The gas flowmeter here reported is a movable L tube flowmeter of angular momentum type with a thermometer and a manometer. Such a flowmeter enables us to know the mass flow rate of a gaseous substance by measuring the torque on the movable L tube, the temperature and pressure at the inlet (or outlet) end of the tube. The theory of the flowmeter assumes the uniformity of velocity at the inlet (or outlet) end. When this assumption is invalid, the discharge coefficient becomes necessarily to correct the error. The experimental results show that the discharge coefficient for gas is equal to that for liquid, and the latter can be known experimentally with liquid.