A Study into Tubing Shear Stresses in High Rate Wet Gas Producers

Three different approaches to plasticity are investigated to model the experimentally-observed non-linear behaviour of unidirectional fibre-reinforced polymeric matrix materials. The first and simplest approach consists on assuming independent one-dimensional rate-dependent plasticity on in-plane (12) and through-thickness longitudinal (13) shear components of the Cauchy stress tensor. The second, employs a 3D extension of the plane stress Hill’48 anisotropic plastic surface. The third and the last is formulated as a quadratic yield function inspired by Puck’s fracture initiation criterion. It searches for a plastic localisation plane in which a certain combination of normal and shear stresses is maximum. Numerical simulations are conducted to analyse the off-axis compression behaviour of carbon fibre reinforced epoxy composite under varying loading rates. The afore-mentioned three different approaches are explored with an aim to predict the experimentally-observed non-linear response of such composites. The model parameters are determined using a deterministic inverse modelling strategy employing an iterative domain reduction optimisation technique. As far as the experiments are concerned, the quasi-static and medium rate tests were carried out in universal testing machines, while the experiments at high rate were conducted in a Split Hopkinson Pressure Bar system. The effectiveness in terms of accuracy and robustness of the three approaches are discussed.

Download Full-text

CFD Applied for the Identification of Stiffness and Damping Properties for Smooth Annular Turbomachinery Seals in Multiphase Flow

Volume 7B: Structures and Dynamics ◽

10.1115/gt2016-57905 ◽

2016 ◽

Cited By ~ 4

Author(s):

Andreas Jauernik Voigt ◽

Piero Iudiciani ◽

Kenny Krogh Nielsen ◽

Ilmar F. Santos

Keyword(s):

Multiphase Flow ◽

Volume Fraction ◽

Bubbly Flow ◽

Primary Phase ◽

Test Facility ◽

Liquid Volume ◽

Shear Stresses ◽

Liquid Volume Fraction ◽

Wet Gas ◽

Stiffness And Damping

This paper presents a first venture into quantifying stiffness and damping coefficients for turbomachinery seals in multiphase flow using Computational Fluid Dynamics (CFD). The study focusses on the simplest seal type: the smooth annular seal. The investigation is conducted for both wet-gas and bubbly flow regimes in which the primary phase is gas (air) and liquid (water), respectively. For the wet gas regime three different Liquid Volume Fraction (LVF) conditions are included in the study; 5%, 3% and 0%. Similarly for the bubbly flow regime three Gas Volume Fractions (GVF) conditions are included; 5%, 3% and 0%. An Eulerian-Eulerian modelling approach is taken, applying an inhomogeneous model, where the primary phase is treated as continuous and the secondary phase is included as dispersed. The Instationary Perturbation Method (IPM) is applied to identify the rotordynamic coefficients, in which the rotor is harmonically perturbed, and forces acting on the rotor are quantified through integration of the pressure and shear stresses. The perturbation is repeated for different frequencies to uncover any frequency dependence. The results presented in this paper are intended as an initial comparison basis for the experimental results to be obtained by applying the multiphase seal test facility currently in development, as part of a collaboration between Lloyd’s Register Consulting, the Technical University of Denmark, OneSubsea, TOTAL and Statoil.

Download Full-text

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069272 ◽

1970 ◽

Vol 28 ◽

pp. 456-457

Author(s):

L. E. Murr ◽

G. Wong

Keyword(s):

Single Crystal ◽

High Vacuum ◽

Ultra High Vacuum ◽

High Rate ◽

Flash Evaporation ◽

Optimum Load ◽

Single Crystal Films ◽

Crystal Films ◽

A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Download Full-text

Rapid Freezing of Freeze-Etch Specimens

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600003275 ◽

1980 ◽

Vol 38 ◽

pp. 752-755

Author(s):

A. Elgsaeter ◽

T. Espevik ◽

G. Kopstad

Keyword(s):

Low Temperature ◽

Metal Surface ◽

Relative Velocity ◽

Thermal Contact ◽

High Rate ◽

Rapid Freezing ◽

Temperature Decrease ◽

Freeze Etching

The importance of a high rate of temperature decrease (“rapid freezing”) when freezing specimens for freeze-etching has long been recognized1. The two basic methods for achieving rapid freezing are: 1) dropping the specimen onto a metal surface at low temperature, 2) bringing the specimen instantaneously into thermal contact with a liquid at low temperature and subsequently maintaining a high relative velocity between the liquid and the specimen. Over the last couple of years the first method has received strong renewed interest, particularily as the result of a series of important studies by Heuser and coworkers 2,3. In this paper we will compare these two freezing methods theoretically and experimentally.

Download Full-text