Showing papers on "Slip ratio published in 1986"

The rheological characterization of HPG gels: Measurement of slip velocities in capillary tubes

Abstract: Measurements are reported for the properties of two hydroxypropyl guar (HPG) gels. The flow curves are composed of three distinct regions: a yield value at low stress levels, a quasi-linear region at intermediate stress or deformation rate levels, and a broad region at high deformation rate levels in which the flow is entirely dominated by slip phenomena.

An analysis of apparent slip flow of polymer solutions

Abstract: Theapparent slip flow phenomenon of polymer solutions in capillary tubes is analyzed by a thermodynamic diffusion model. An approximate solution of the developing concentration profiles shows a significant decrease in the polymer wall concentration. The approximate concentration profiles are coupled with the concentration-dependent viscosity for aqueous polyacrylamide solutions to provide a priori predictions of the magnitude of the effective slip velocity at the wall. The results are in a reasonable agreement with the available apparent slip data for 1% and 0.5% solutions of partially hydrolyzed polyacrylamide.

On the behavior of a slightly rarefied gas mixture over plane boundaries

Abstract: The behavior of a slightly rarefied gas mixture bounded by plane boundaries is investigated on the basis of the linearized Boltzmann equation ofB-G-K type for gas mixtures under the diffusive boundary condition. A useful result of the present analysis is that the macroscopic equations and the appropriate boundary conditions in terms of slip and jump are obtained together with the Knudsen-layer corrections near the boundaries. This system of equations makes possible the treatment at fluid dynamic level for various problems of gas mixtures with plane geometry which require kinetic theory consideration. As an application of this system, some basic flow problems of a slightly rarefied gas mixture, namely, Couette flow, thermal slip flow and diffusion slip flow between two plates are taken up. The total velocity distributions of these concrete problems are explicitly obtained for the first time, and their dependence on the properties and concentration of the component gases in the mixture are clarified in some detail.

Simultaneous Measurements of Bubble and Liquid Velocities in Two-Phase Bubbly Flow Using Laser Doppler Velocimeter

Abstract: Simultaneous measurements of local velocities of both phases in a two-phase bubbly flow have been successfully made using a laser Doppler velocimeter (LDV). First, an exact theory which forms the basis of the velocity measurement of a large particle, such as bubble, has been derive and its validity has been applied to an air-water vertical bubbly flow. As a result, it has become evident that the measured value of a local slip velocity between bubble and liquid is lower than a terminal velocity of a single bubble rising in still water, and that the slip velocity gradually decreases with an increase in the mean liquid velocity.

Anti-skid control based on duty cycle adjustment

Abstract: Disclosed is an anti-skid control system incorporated in the hydraulic pressure braking apparatus of a motor vehicle including a wheel braking cylinder responsive to a hydraulic pressure developed by a master cylinder for braking a wheel of the vehicle. The anti-skid control system comprises a hydraulic pressure supplying device and a directional control valve provided between the wheel braking cylinder and the hydraulic pressure supplying device. The directional control valve is actuated to shut off the communication therebetween and the actuation thereof is controlled in accordance with a duty cycle, which is in turn updated in accordance with the difference between a wheel speed and a target wheel speed so that the slip ratio of the wheel becomes equal to a target slip ratio.

Stokes Roughness Effects on Hydrodynamic Lubrication. Part II—Effects Under Slip Flow Boundary Conditions

Abstract: Stokes roughness effects on hydrodynamic lubrication are studied in the slip flow regime. Slip flow boundary conditions for Navier-Stokes equations are derived, assuming that the fluid on a surface slips due to the molecular mean free path along the surface, even if the surface is rough. The perturbation method for Navier-Stokes equations, which was derived in Part I of this report, is then applied. Slip flow effects on load carrying capacity and frictional force are numerically clarified for both Stokes and Reynolds roughnesses. In the slip flow regime, second-order quantities induced by Stokes effects, such as flow rate, load carrying capacity, and frictional force are in proportion to the wavenumber squared. This phenomenon relative to the quantities being proportional is also the same as that in the continuum flow regime. As a result of velocity slippage, the load carrying capacity in Stokes roughness is found to decrease more than in Reynolds roughness for incompressible films, while the relationship is reversed for compressible films having a high compressibility number. The simulation of random roughness, which is generated by numerical means, clarifies one important result: the average slip flow effects associated with random Stokes roughness become similar to the slip flow effects in deterministic sinusoidal Stokes roughness, whose wavelength and height are statistically equivalent to those of random roughness. Although attention should be given to the fact that Stokes effects on random roughness demonstrate considerable scattering with the continuum flow, such scattering diminishes with the slip flow.

Slip controlling method for driving wheel of vehicle

Abstract: PURPOSE: To prevent the lowering of a driving force by judging that excessive slip is detected when a variable corresponding to the slip ratio of a driving wheel becomes above a set value corresponding to the reference slip ratio of said driving wheel, and increasing said set value when vehicle speed is below a defined speed. CONSTITUTION: The output signals of speed sensors 21W24 for detecting the speeds of right and left driving wheels 11, 12 and right and left driven wheels 13, 14 at the time of operating a vehicle are taken in an ECU35. In this ECU35, the excessive slip of the right and left driving wheels 11, 12 is detected based on the speed of the right and left driven wheels at the time of the accelerating operation of the vehicle and, when excessive slip is detected, a fuel injection valve 36 is controlled to restrict the slippage of the driving wheels 11, 12. In this case, vehicle speed is detected based on the speed of each of driven wheels 13, 14, while setting a set value corresponding to the reference slip ratio of the driving wheels. And, when a variable corresponding to this reference slip ratio becomes above the set value, it is judged that an excessive slip is detected and the set value, it is judged that an excessive slip is detected and the set value is set large when vehicle seed is lower than a defined speed. COPYRIGHT: (C)1987,JPO&Japio

Wire drawing machine

Abstract: PURPOSE:To improve product quality and to prolong machine life by setting a speed change gear on a connecting device for every couple of capstans. CONSTITUTION:Two couples of cone type capstans 2, 3 and 4, 5 are set on the machine body 1 and a connecting device 9 is provided with a speed change gear 14. All capstans 2, 3, 4, and 5 are drived and a wire is fed to a die 6. After the total length of the wire passes through the die 6, a wire drawing is performed at a small slip ratio by adjusting the speed of capstans near the inlet side to the speed of capstans on the wire finishing side using the speed change gear 14. In that time, the accumulated slip on the wire finishing side is increased but the slip is corrected to the minimum slip ratio at the final stage of the inlet side capstans, so that the accumulated slip ration on the inlet side is minimized. Therefore, the product quality is improved and the machine life is prolonged through reduction of friction between the wire and the capstans.

Automobile slip control device

Abstract: PURPOSE: To set the slip ratio of a driving wheel to be the optimum in accordance with change in the ground contact load of said driving wheel by correcting the target value of the slip of said driving wheel in accordance with a road face gradient. CONSTITUTION: A torque adjusting means (c) adjusts an applied torque to a driving wheel (a). A slip control means (e) receives an output from a slip detecting means (b) and controls the torque adjusting means (c) so as to make the slip of the driving wheel (a) to be a defined target value. A target value correcting means (f) corrects the target value in accordance with a road face gradient (d). On an upward slope where a ground contact load at the time of cornering becomes small, it reduces the target slip ratio of the driving wheel (a) increasing a lateral force. When the ground contacting load of the driving wheel (a) becomes small on a straight upward slope, the target slip ratio is made large to increase gripping force. COPYRIGHT: (C)1988,JPO&Japio

Drive force control device in front and rear wheel drive vehicle

Abstract: PURPOSE:To restrain the generation of slips and to obtain a relatively large drive force, by controlling torque transmitted to at least either one of front and rear wheels to obtain a desired slip ratio between the front and rear wheels. CONSTITUTION:A clutch means 14 for enabling transmission torque to be changed is disposed in at least one of power transmission systems for front and rear wheels 12, 13, between an engine 11 and the front and rear wheels 12, 13. There are provided sensors 15, 16 for detecting the rotational speeds of the front and rear wheels 12, 13, from which output signals are delivered to a means 17 for calculating the slip ratio between both wheels 12, 13 in accordance with the signals. A control means 19 compares the thus obtained slip ratio with a desired slip ratio set on a desired slip ratio setting means 18, and controls the clutch means 14 to change the transmission torque of the clutch means 14 so that the slip ratio between the front and rear wheel reaches the desired slips ratio.

Braking controller for vehicles

Abstract: PURPOSE:To aim at reduction in a braking distance, by setting the desired revolving speed of each wheel on the basis of a slip ratio in response to braking instructions of a driver as well as setting the extent of braking hydraulic pressure on the basis of an optimum feedback gain complying with a dynamic model in a system related to braking CONSTITUTION:There is provided with a slip ratio setting device M7 which sets a slip ratio of each wheel M3 according to braking instructions of a driver, and thereby the desired revolving speed of each wheels M3 is set by a setting device M8 on the basis of the set slip ratio and the car body speed made by a car body speed detecting device M2 And, braking pressure for securing this desired revolving speed is found by a brake controlling device M9, and according to the output, a braking pressure regulating member M6 is controlled This brake controlling device M9 is constituted as an additional integration type optimum regulator which determines the braking pressure for the braking member M5 on the basis of an optimum feedback gain being preset according to a dynamic model in a system related to braking of a car M1

A Method of Computing Hydraulic Reaction Force Due to a Fluid Jet at a Steamline Break

Abstract: A method of computing hydraulic jet reaction force at a 100% steamline break is presented. The steamline break analysis is performed by the use of the NOTRUMP code. Formation of supersonic flow at the converging-diverging flow restrictor is computed with a homogeneous equilibrium model. Consideration is given, however, to the slip ratio of the liquid and steam phases, thermal nonequilibrium effects, and normal and oblique shocks.