In this paper, the frictional resistance of the flat plate, placed in the uniform stream along its direction, is calculated by the variational method. The functional J of the velocity distribution is constructed, its stationary value being equal to the shearing stress on the surface of the plate. The Euler equation for δJ=0 is same as the equation of motion. The problem is solved by Ritz's method. The obtained value of the resistance coefficient of the plate of length l is c_f=1.333√(ν/U₀l), where ν is the kinematic coefficient of viscosity and U₀ is the uniform velocity. The equations used to reduce this result are regarded as the equations of the balance of energy and momentum in the boundary layer.

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In this paper the authors deal with the problem about the flow of the fluid emitted from a long slot in the wall of a straight pipe. Such a problem has been occurred in many cases in chemical engineering practice. Two kinds of the brass pipes are used for the experiments. Each one has a long axial slot in its wall. The pressure distribution along an axis of the pipe and the quantity of the fluid flowing through each lateral section inside of it are determined by solving differential equation which can be obtained from energy relations. There is a close agreement between the theoretical and experimental distributions of pressure along the pipe axis.

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In this paper the authors deal with the problem about the flow of the fluid inhaled through a long slot in the wall of a straight pipe. Such a problem has been occurred in many cases in engineering practice. Two sorts of the brass pipes, 34.7 mm and 28 mm in the inside diameter, are used for the experiments. Each one has a long axial slot of 2 mm wide in its wall. The pressure distribution along the axis of the pipe and the quantity of the fluid flowing through each lateral section inside of it are determined by solving differential equation which can be obtained from energy relations. There is a close agreement between the theoretical and experimental distributions of pressure along the pipe axis.

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In this paper, we studied experimentally on the running conditions of pump, when the pumping system falls in surging. We recorded the total head, discharge and motor imput by the oscillograph, and we obtained the closed curve which is described by the instantaneous points (H_p, Q) in the H_p (total head)-Q (discharge) plane. The results showed that (1) these closed curves were described in the direction of counter clock-wise, (2) the instantaneous discharge never attained to the negative range, (3) ΔH_p and ΔQ : that they are difference between maximum and minimum values, were less than those which were ever described by the other authors.

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In our first report the form of Feuerheerd type rotary pump was solved analytically, and now in this report the theoretical discharge quantity of this pump is investigated. We obtained a result that the theoretical discharge Q is given by the following equation, [numerical formula], where n=r.p.m., l=width of the pump, α=radius of base circle of the pump rotar, r=radius of the circular arcs of the rotar, 2γ₁=central angle of the arcs, λ=r/α.

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Experimental and theoretical research was made upon the contraction and coefficient of radial flow at the circular clearance between nozzle hole of the pneumatic micrometer attachment and meusuring surface. It was proved that a small chamfering, whose radious is one half of the clearance, arround nozzle hole resulted the stable performance and enlarged magnification, also that the most desirable thickness of nozzle flange was 0.5-1 ratio to the hole radius.

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In this report the author described the application of the experimental and theoretical results which had been reported on the 1 st∼4 th reports and in addition the experimental results of two newly-designed technical absolute viscometers. The one is a viscometer whose jets are non-rounded uniform short tubes and its measuring error is less than 3∼4% for all range, therefore its accuracy is higher than the Redwood viscometer obtained in our markets. The other one is a viscometer whose jets are the short tubes with divergent exits, and the kinematic viscosity can be given by multiplying the jet factor x by time of efflux T sec. (effluxed volume is 25 cc) and its measuring error is less than 2% at the measuring ranges of these jets. As this viscometer is wieldy and strong in construction and high accuracy, it is very suitable for any practical use.

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The circular distribution of pressure along the outer radius of gear was measured. When δ (=radial tip clearance of gear pump) was small and μ N/P (μ=viscosity of oil, N=no. of revolutions of gear, P=pressure applied to oil by gear pump) was large, it was concave, and when δ was large and μ N/P was small, it was convex. As a result of measuring the total efficiency of gear pump, the best value of the clearance δ which had been formerly derived theoreticaly by the present author was proved to be true.

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As there were not any study of the abrasion between the rigid body and the rigid body in the current liquid, the present author studied on the abrasion of metals to the fluid with sand grains as the study in this case. In this report, he deseribes his study on the fundamental mechanism of abrasion of the pelton wheel's backets to the fluid with sand particles, and reports on the relation between the radius of curvature of the semicircular section of the backet, the static pressure of the flow water and the wear.

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