Investigation on the ball screws no-load drag torque in presence of lubrication through MBD simulations

2021 ◽  
Vol 161 ◽  
pp. 104328
Author(s):  
Antonio Carlo Bertolino ◽  
Giovanni Jacazio ◽  
Stefano Mauro ◽  
Massimo Sorli
Keyword(s):  
Drag Torque

New Development of a Gas Cavitation Model for Evaluation of Drag Torque Characteristics in Disengaged Wet Clutches

2016 ◽  
Vol 9 (3) ◽  
pp. 1910-1915 ◽  
Author(s):  
Shahjada A. Pahlovy ◽  
Syeda F. Mahmud ◽  
Masamitsu Kubota ◽  
Makoto Ogawa ◽  
Norio Takakura
Keyword(s):  
Drag Torque ◽  
Cavitation Model ◽  
New Development

Performance of Hydrostatic Spherical Gas Gyro Bearings

1976 ◽  
Vol 98 (1) ◽  
pp. 111-116 ◽  
Author(s):  
A. Gu ◽  
L. Cziglenyi
Keyword(s):  
Numerical Solution ◽  
Flow Rate ◽  
Gas Flow ◽  
Load Capacity ◽  
Performance Data ◽  
Drag Torque ◽  
Fixed Bearing ◽  
Gas Flow Rate

Analysis and method of numerical solution for evaluating the performance of hydrostatic spherical gas gyro bearings at any gimbal angle and at any eccentricity have been developed. Performance data on load capacity, gas flow rate, drag torque, and error torque over some ranges of gimbal angle and eccentricity are presented. Comparison has been made between the equatorially vented and nonvented bearings of fixed bearing angles.

The aerodynamic resistance to a sphere rotating at high Mach numbers in the rarefied transition régime

1966 ◽  
Vol 293 (1433) ◽  
pp. 156-168 ◽  
Keyword(s):  
Experimental Study ◽  
Aerodynamic Resistance ◽  
Pressure Gauge ◽  
Transition Regime ◽  
Drag Torque ◽  
Free Molecule ◽  
Rotating Sphere ◽  
Mach Numbers ◽  
High Mach ◽  
Molecule Flow

An experimental study has been made of the gaseous drag torque on an isolated sphere rotating at high Mach numbers. The sphere was suspended electromagnetically and spun by induction. The drag torque has been measured through the transition régime from continuum to free molecule flow at Mach numbers (based on equatorial speed) of up to about five. These high Mach numbers were achieved in heavy vapours (diiodomethane, germanium tetrabromide and stannic bromide) with sonic speed as little as a quarter of that in air. To measure the pressure in the vapour a second (smaller) rotating sphere was used as a pressure gauge. The results agree well with those previously obtained and show an unexpected Mach number dependence in the transition régime.

Measurements of Apparent Mass Torque Coefficients of Two-Dimensional Centrifugal Impellers

1986 ◽  
Vol 108 (4) ◽  
pp. 407-413
Author(s):  
Y. Tsujimoto ◽  
K. Imaichi ◽  
T. Moritani ◽  
K. Kim
Keyword(s):  
Angular Velocity ◽  
Flow Rate ◽  
Potential Flow ◽  
Rotational Velocity ◽  
Apparent Mass ◽  
Two Dimensional ◽  
Drag Torque ◽  
Mean Flow ◽  
Experimental Values

Apparent mass torque coefficients for fluctuations of flow rate and angular velocity are determined experimentally for two-dimensional centrifugal impellers. Nearly sinusoidal fluctuations of flow rate and angular velocity are produced by using crank mechanisms, and the resulting unsteady torque on the impeller is measured. The torque is divided into components in-phase and out-of-phase with the displacements. The in-phase components are used to determine the apparent mass coefficients. Drag torque coefficients are defined and used to represent the out-of-phase components. The tests are conducted under various frequencies and amplitudes of the fluctuations with zero mean flow rate and rotational velocity. The apparent mass torque coefficients are compared with theoretical values obtained under the assumption of a two-dimensional potential flow. The experimental values are 5 to 20 percent larger than the theoretical ones and no appreciable effects of the frequency and the amplitude are observed within the range of the experiments.

The aerodynamic resistance to a rotating sphere in the transition régime between free molecule and continuum creep flow

1964 ◽  
Vol 279 (1376) ◽  
pp. 39-49 ◽  
Keyword(s):  
Rarefied Gas ◽  
Aerodynamic Drag ◽  
Aerodynamic Resistance ◽  
Reynolds Numbers ◽  
Approximate Theory ◽  
Drag Torque ◽  
Free Molecule ◽  
Steel Sphere ◽  
Creep Flow ◽  
Wide Range

An experimental and theoretical study has been made of the aerodynamic drag torque on a sphere rotating in a rarefied gas. The drag torque on a magnetically suspended polished steel sphere rotating in air was measured over a wide range of Knudsen numbers from continuum to free molecule flow and for several different Mach numbers up to ca . 1. The drag under free molecule conditions was found to be consistent with the assumption of perfectly diffuse reflexion of molecules at the surface of the rotor. An approximate theory is derived which is analogous to Millikan’s solution to the problem of plane Couette flow and is valid for low Mach and Reynolds numbers. Theory and experiment are found to agree to within 10 % in the range investigated, for Reynolds numbers less than ca . 20.

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