Showing papers by "Itzhak Green published in 1986"

Nonlinear Dynamic Analysis of Noncontacting Coned-Face Mechanical Seals

Abstract: The complete nonlinear equations of motion of a flexibly mounted stator in a noncontacting coned-face mechanical seal are solved numerically. The solution utilizes a transient dynamic analysis and takes into account rotor axial runout and assembly tolerances in the form of initial stator misalignment. Cavitation of the fluid film is also accounted for. A parametric investigation is performed and the effect of various design parameters and operation conditions on the seal dynamics is presented and discussed. A critical shaft speed is found above which the seal becomes dynamically unstable. A critical rotor runout is found which, if exceeded, will cause seal failure due to local face rubbing contact. A comparison is made between the numerical results and those of a simpler analytical solution. It is found that the analytical solution is valid for most practical applications of mechanical seals. Presented at the 40th Annual Meeting in Las Vegas, Nevada May 6–9, 1985

Pressure and Squeeze Effects on the Dynamic Characteristics of Elastomer O-Rings Under Small Reciprocating Motion

Abstract: A test procedure is described by which quick measurements of stiffness and damping coefficients of elastomer O-rings can be made for a wide range of the parameters affecting O-ring dynamics. Tests were performed to investigate the effects of squeeze and pressure on the dynamic characteristics of Nitrile (Buna N) and Fluorocarbon (Viton 75) O-rings. Results of these tests are presented and discussed.

A Kinematic Model for Mechanical Seals With Antirotation Locks or Positive Drive Devices

Abstract: A kinematic model of mechanical face seals is presented. Two basic seal arrangements are considered: a flexibly mounted stator with antirotation locks, and a flexibly mounted rotor with positive drive devices. The equation of kinematic constraint is derived and presented in a simple form for all the possible types of antirotation or positive drive mechanisms found in practical seals. This simple form is then used to derive the dynamic moments acting on the flexibly mounted element of the seal.

Transient Temperature Distribution in Partially Filled Rotating Horizontal Cylinders

Abstract: The transient temperature distribution in an infinitely long horizontal rotating cylinder which is partially filled by a viscous fluid is calculated. Thermal boundary and initial conditions are such that the fluid starts from a uniform temperature, and that the outer boundary (cylinder surface) is isothermal at a different temperature. Nondimensional analysis shows that the problem can be fully described by a properly defined Fourier modulus and a normalized bubble eccentricity.