The results of the experiments on the motion of pressed and solid cages guided by the rolling element of balls are summarized as follows: (1) The pattern of the motion of pressed cages resembles that of the cages guided by bearing rings. The pressed cages rotate with the posture moving with the parallel motion, inclinating in the axial direction, and varing their revolving speed. (2) The solid cages revolve with a uniform angular velocity under conditions of large eccentricity, inclined in the axial direction and held firmly by some of the balls in the ball bearing.
In order to investigate accuracy and convergence characteristics of any unsteady lifting surface computation programs, it is found that "DLM-C" scheme for two-dimensional airfoils developed by us is quite useful. This scheme is reliable up to high reduced frequencies k and high subsonic free stream Mach numbers M. It has comparable efficiency with NASA 2-D, within the published k and M values. For a rectangular wing of aspect ratio ten chordwise lift distributions on the midspan section are computed by using some unsteady lifting surface programs, which are compared with DLM-C. The values of error-index parameters E are entered in a k vs M diagram, and constant E curves are drawn. This diagram shows clearly the upper limit of k where the scheme is efficient.
Aerodynamic characteristics of slender wing-gapbody combinations are studied exactly in the frame of the slender-body theory. In our previous paper, the solutions of total lift and lift curve slope are obtained, in which the wings and the body have different incidence with respect to the free stream, and arbitrary width of chordwise gaps exist between the wings and body. In this work, the induced drag as well as the lift is evaluated exactly. This requires that the lift due to wings and one due to body are separately known. Together with the solutions of our previous paper, many problems in which missile aerodynamicists have interest may be covered.
An experimental study has been made of the initiation of planar blast waves by gaseous detonations. The gaseous detonation initiated by DDT process is submitted into a long tube filled with air at various initial pressures. The measurement of decaying process of a produced shock wave indicates that it can be treated as a "plane source" blast wave, although there exists a secondary shock wave, which may be a retonation wave refleCted on an end wall of a driver tube, behind the blast Wave front. As a result, the decays of a propagation Mach number and a peak overpressure of the wave front as a function of a distance from the initiation source and the initial pressure of the medium are found to be described by the quasi-similar theory of the idealized plane source blast wave. Comparing the experimental results with the theory leads to the estimation of an initiation energy of the blast wave. The initiation energies of oxyhydrogen detonations for three different mixture strengthes, three different initial pressures and two different size of the driver tube are estimated to show that about 30-40% of the chemical energy contained initially in the driver tube is used to initiate the blast wave.
The plasma properties in the discharge chamber of a quasi-steady MPD thruster have been investigated to understand acceleration mechanism and to design an optimum electrode configuration. The results measured by a magnetic probe show that the current pattern depends strongly on the propellant species (Ar, H2 and NH3) and the parameter JJ2/m (current squared over mass flow rate). It is found that the plasma produced in the discharge chamber is compressed radially and 50% on the input power is consumed in the cathode region for H2 at higher currents. From floating potential and number density measurements, the positive voltage slope and propellant starvation near the anode surface are found to occur beyond the predicted critical value of JJ2/m. With improved straight-diverging anode, satisfactory arc operation without anode erosion has been demonstrated somewhat beyond the predicted Critical Current.
A basic experiment of the sublimation heat transfer of solid cryogen has been conducted for its potential applications to cryogenic cooling of onboard instruments. The most serious concern is the separation of solid cryogen from a cooling section caused by local rapid sublimation (dry-out). The condition of the dry-out initiation and the heat transfer performance in the dry-out state was especially pursued in this paper. It is found from the experiments that the dry-out occurs sooner or later whenever heat is applied to solid cryogen and that heat transfered through the vapor phase is almost consumed upon sublimation of solid cryogen at the phase boundary. The order of the effective thermal conductivity of porous solid nitrogen was found to be almost the same as that of pure one and far smaller than that predicted in the sublimation-filtration. condensation (SFC) process. Application of the solid cryogen to onboard cooling is also discussed.