Axial Thrust Force Research Articles

SURFACE ROUGHNESS EFFECTS ON FLOW BETWEEN STATIONARY- AND ROTATING DISCS

The turbulent outward fluid flow between stationary and a rotating disc enclosed by a cylindrical housing has been investigated experimentally . This type of flow occurs in many applications of engineering interests . Most of the flows enco-untered in practice are turbulent specially in turbo-machinery. The effect of surface roughness on the friet.ional voment of the rotating disc as well as on the radial pressure distributi-ons has been investigated for different relative roughness ratios of the rotating disc CR/k),16005CR/k35I6401 . Here k is the mean particle diameter of the used grain size and R is the outer disc radius . The flow is investigated at a dimensionless gap height CID of 10.013 SCHmh/10.15 0.401, mass flow coefficient CCw er 11.0x103 5CCwapWeR35 4.2x103 and rotational Reynolds number (Re) of 13x1055 (Re•peR2/0)5. 1.21x 1061. Radial pressure and frictional moment for rough discs are compared with the experimental results obtained on smooth rotating discs . The results have showed that the surface roughness affects strongly upon the radial pressure distribution, the frictional moment and the axial thrust force .

コンクリート充填構造要素のせん断耐力 : その1 基本せん断耐荷機構の研究

This paper deals with an analysis of the ultimate strengths of concrete filled steel box elements subjected to an arbitrary combination of axial thrust, bending moment and shear force. A significant ultimate shear resitance of this composite is characterized by a stable truss action of both materials such that diagonal compression field develops through the filled concrete, while tension field is formed along the opposite diagonal direction of the steel web plates. An ultimate strength analysis was achieved based on the assumed ultimate stress field which reflects the above material behaviors. The solution is given explicityly in the form of an ultimate strength interaction curve of axial thrust and shear force. A notable feature of the solution is that this can be constructed graphically by use of the individual interaction curves for the filled concrete and the peripheral steel element, where each curve is obtainable independently of the other. Accuracy of the solution was examined by a series of experiment. It is verified that the solution gives, on the whole, a conservative estimate of the actual strengths of the tested specimens. More specifically, (1) the predicted strength is sufficiently accurate for the specimens with shear collapse mode, while for the specimens with bending collapse mode errors increase toward conservative side. (2) The solution is more accurate for the specimens whose steel elements have smaller volume fractions.

Side Thrust Control by Secondary Gas Injection into Rocket Nozzles

Directional control of rockets can be achieved by using secondary gas jets for providing side forces. The present investigation is concerned with the fact that a greater side force can be achieved by expanding the secondary gas into the supersonic region of the main nozzle than by expanding it directly to atmosphere. A laboratory test rig using ambient temperature air for the primary and secondary flows is described. Axial thrust and side force were measured using strain gauge force transducers. The experiments were performed on a small axisymmetric main nozzle with a 10° semi-angle of divergence and with sonic injection through circular ports placed normal to the main nozzle axis. The investigations centred principally on the effects of (1) varying the secondary port size at a given axial location in the nozzle and of (2) varying the axial location of a port of constant diameter. Side force and axial thrust augmentation characteristics were obtained for a range of primary and secondary flow inlet pressures. The results show the relative importance of the parameters on which side force depends, the maximum side force that may be produced and the interdependence of axial thrust augmentation and side force.

岩石の切削抵抗に関する研究

A rotary bit penetrates into the rock along a helical path under the action of an axial thrust force and a rotary torque and the action of the cutting tip is one of planing. It seems reasonable to assume, therefore, that a study of the planing action of a tool on rock would reveal much information to rotary drilling or boring.Then, we have studied on the following problems using a rock planing apparatus which is able to measure horizontal and vertical component of cutting resistance of rock: 1) effect of depth of cut, 2) effect of number of free surface, 3) effect of width of cutting tip, 4) effect of wear of cutting tip, etc.