The motion of revolving cages guided by the bearing rings is measured in the three dimensional directions under various experimental conditions by the non-contacting displacement vibrometer and is measured in the revolving direction by the stroboscope. The running cages oscillate in the three dimensional directions and in the revolving direction, especially they have very large amplitude and parallel oscillation in the axial direction. The oscillations of the integral numbers' frequencies, 1, 2, 3, …times as large as the revolving speed of the cages, are usually contained with in the motion. It seems that oscillations of the cages are brought about by contacting conditions between balls and cage pockets in the running. The amplitude of oscillations are not so subjected to the effect of revolving speed, loading directions and magnitude of load.
This paper presents an experimental study of reverse transition in a turbulent boundary layer along a corner of contraction of rectangular section. The reverse transition was examined by consideration of the velocity distribution and the contours of axial mean velocity and turbulent intensity. It is found that a turbulent corner flow reverses to laminar in the presence of favourable pressure gradient and the well-known secondary flow of second kind generated in a corner region disappears during the reverse transition process.
This paper concerns with the kernel function which appears in the subsonic lifting surface theory. There are two parts. In Part I, evaluation method of the so-called integral function B is discussed. In a previous paper the present authors proposed an improved evaluation method, about which a few "demerits" were pointed out by some readers. These "demerits" however are trivial according to the present investigation. For small k (reduced frequency), an ultra near field approximation formula (BUS) is useful. It is noteworthy that B for small k and/or small W is combined into BUS, where the product kW plays an important role. For small r, the function Qr(r) can be calculated using double precision without any difficulties. In addition an ultra far field approximation formula BUL is effective for kW>50…though it is irrespective of "demerits." Both in Bus and BUL, the product kW is a controlling independent variable. Thus advantages resulting from kX and kr over X and r become much clearer. Part II presents an ideal form of the overall kernel function. The singular terms are written by using the original independent variables, which make analytic treatment much more convenient. On the other hand the finite terms preserve their favourable formes for numerical evaluation.
Simplified analytical equations are derived from numerical checking of the order of each terms in the theoretical equations in the authors' previous paper. These equations yield a simple mechanical explanation for the mechanism of self-excitation in Pogo. Furthermore a simple expression for discrimination of stability is derived for the case including the influences of the longitudinal vibration of liquid in the long feed pipe, of the cavitation in the pump, and of the function of an accumulator as a suppression device. The expression makes it easy to understand the effect of each factor on the self-excitation. A model experiment corresponding to the present simplified analytical model was carried out in laboratory. The test model was installed on an electro-magnetic shaker and the force corresponding to the thrust variation proportional to the flow velocity variation in the discharge pipe was given by the shaker. The occurrence of a self-excited oscillation under the mechanism clarified in the present analytical study was confirmed by this experiment. Furthermore the effect of oscillation of liquid surface was measured.