Showing papers on "Slip ratio published in 1974"

Microscopic wear grooves on slickensides: Indicators of paleoseismicity

Abstract: The frictional wear of Westerly granite surfaces polished with 0.3-μm Linde A polishing compound was studied on triaxial compression specimens for slip up to 3 mm at confining pressures to 2.9 kbar. A stable sliding to stick-slip transition occurs at 0.3-kbar confining pressure. Frictional wear occurs on the polished sliding surface only when the specimens undergo stick-slip. The initial wear on the surface consists of microscopic carrot-shaped grooves whose length rarely exceeds the maximum slip accompanying one stress drop during stick-slip sliding. The preferred orientation of the carrot-shaped grooves is such that the tip points in the direction of motion of the surface containing the grooves. A groove length equivalent to individual slip distance results in a small groove length to total slip ratio (<1:5) that may be used as a criterion for stick-slip sliding. A small groove length to total slip ratio also occurs on two natural slickenside surfaces, and on the basis of the laboratory experiments these natural surfaces are thought to be samples from fault zones that were once seismically active. The experimental observation that maximum groove length closely approximates the slip during the seismic event suggests that the seismic moment of prior earthquakes on a fault may be calculated without prior knowledge of seismicity.

Hydrodynamic stability of plane porous slip flow

Abstract: The hydrodynamic stability of the flow between two plane porous plates with velocity slip at the plates is examined using a finite difference scheme. Results in the form of critical Reynolds number as a function of cross flow with velocity slip as a parameter are given.

Slip Factor of a Centrifugal Compressor and Its Variation with Flow Rate

Abstract: To predict the complete performance map of turbocharger centrifugal compressors, it has been found essential to include a procedure for estimating the slip factor at off-design flow rates. The many correlations available for the slip factor only concern themselves with design-point operation and consequently only provide a single value for the slip factor. The approach presented here attempts, within the confines of a one-dimensional procedure, to recognize the changing flow pattern at the impeller discharge in order to predict the variation of slip factor with flow rate. The procedure is based upon the well-established jet-wake flow model of Dean and the overall slip factor calculated from the jet slip factor.Experimental and theoretical slip factors are presented for three impellers with 34, 30 and 12 radial blades, respectively. The complete performance map of the 12-bladed turbocharger compressor and the effect of using a constant and varying slip factor on the predicted performance are presented.

Influence of hall effect and ion slip on velocity and temperature fields in an MHD channel

Abstract: The combined influence of viscosity, Hall effect and ion slip on hydrodynamic fields and on heat transfer is investigated. The exact solutions for velocity, induced magnetic field and temperature are derived for the laminar MHD flow in a flat channel assuming a small magnetic Reynolds number, finely segmented electrodes, fully developed flow and uniform heat flux at channel walls. The internal generation of heat is not considered. The Kantorowitsch method of variational calculus is employed to approximate the complicated velocity distribution.

Measurements of individual alumina particle velocities and the relative slip of different-sized particles in a vertical gas - solid suspension flow using a laser - anemometer system

Abstract: Particle velocities in a vertically upward gas-solid suspension flow have been measured using a laser-Doppler anemometer system. The electronic signal-processing equipment enables individual particle slip velocities to be measured, which in turn allows mixtures of different-sized particles to be successfully studied. Alumina particles in the size range 15-200 μm were used. In laminar pipe flow of fine particles (15 μm) the particle velocity profile is parabolic, but with increasing pipe Reynolds' number the profile becomes flatter. Near the pipe wall smaller particles were unexpectedly found to have greater slip than larger particles. Reasonable agreement was found between the measured centre-line slip velocities and those computed by extensive theoretical considerations. For alumina particles in excess of 30 μm diameter, Stokes' law is no longer applicable, and great care must be taken in order to obtain an accurate estimation of the slip.

Skid control system for vehicles

Abstract: In the skid control system disclosed a pressure modulator reduces the pressure applied by a master cylinder to a wheel cylinder when the wheel velocity as measured by a wheel detector decreases faster than a deceleration predetermined by a deceleration control. A control unit which regulates the pressure modulator corrects the predetermined deceleration when the wheel has exceeded the slip ratio at which the coefficient of friction is maximum so as to achieve an optimum deceleration that corresponds to the road surface condition. The control unit induces the pressure modulator to reduce the pressure of the brake fluid and restore the wheel velocity when the coefficient of friction of the wheel reaches the maximum. Emergency braking is thus performed with an average slip ratio at which the coefficient of friction is maximum. A comparator circuit compares the wheel velocity with a signal from the control unit indicative of the velocity of the predetermined decelerator to determine when the wheel velocity has decreased faster than the predetermined deceleration.

Determination of slip ratios in air‐water two‐phase critical flow at high quality levels utilizing holographic techniques

Abstract: Holographic techniques employing a pulse ruby laser were used to measure the size and velocity of drops for air-water two-phase critical flow at quality levels above 0.95. The use of a large numerical aperture in the holographic recording system permitted diffraction limited resolution of the droplets. The measured slip ratio a long withthe observation that a very significant portion of the liquid phase was concentrated near the boundary layer at the exit plane indicates that a separated flow model describing two-phase critical flow would represent the actual conditions to a better degree than the other models.

Slip, friction, and heat transfer laws in a merged regime

Abstract: The phenomenological expressions of the slip velocity, slip temperature, the friction, and the heat transfer rate to the surface in the merged flow regime are determined by comparing the results of numerical integration of the Navier‐Stokes equations with experimental data over the sharp leading edge of a flat plate. The best agreement is obtained with the two‐stream slip models under the surface condition of total diffused reflection. The absolute error bound of the computed results is given as < 15% in the merged regime.