Non-linear conduction in insulating phase of (DMTSA)BF4 under high pressure

2001 ◽  
Vol 120 (1-3) ◽  
pp. 1059-1060 ◽  
Author(s):  
M. Nagasawa ◽  
K. Kawabata ◽  
T. Sambongi ◽  
T. Otsubo ◽  
N. Mori
Keyword(s):  
High Pressure ◽  
Non Linear ◽  
Insulating Phase

scholarly journals Machine Learning for Turbulence Model Development Using a High-Fidelity HPT Cascade Simulation

2017 ◽  
Author(s):  
Jack Weatheritt ◽  
Richard Pichler ◽  
Richard D. Sandberg ◽  
Gregory Laskowski ◽  
Vittorio Michelassi
Keyword(s):  
High Pressure ◽  
Evolutionary Algorithm ◽  
Turbine Blade ◽  
A Priori ◽  
Model Development ◽  
Boussinesq Approximation ◽  
High Pressure Turbine ◽  
Stress Strain ◽  
Non Linear ◽  
Anisotropy Tensor

The validity of the Boussinesq approximation in the wake behind a high-pressure turbine blade is explored. We probe the mathematical assumptions of such a relationship by employing a least-squares technique. Next, we use an evolutionary algorithm to modify the anisotropy tensor a priori using highly resolved LES data. In the latter case we build a non-linear stress-strain relationship. Results show that the standard eddy-viscosity assumption underpredicts turbulent diffusion and is theoretically invalid. By increasing the coefficient of the linear term, the farwake prediction shows minor improvement. By using additional non-linear terms in the stress-strain coupling relationship, created by the evolutionary algorithm, the near-wake can also be improved upon. Terms created by the algorithm are scrutinized and the discussion is closed by suggesting a tentative non-linear expression for the Reynolds stress, suitable for the wake behind a high-pressure turbine blade.

Theorical Analysis of Leakage in High Pressure Pipe Using Acoustic Emission Method

2012 ◽  
Vol 445 ◽  
pp. 917-922 ◽  
Author(s):  
Saman Davoodi ◽  
Amir Mostafapour
Keyword(s):  
High Pressure ◽  
Acoustic Emission ◽  
Degrees Of Freedom ◽  
Oil And Gas ◽  
Pipe Wall ◽  
Leak Detection ◽  
Stress Waves ◽  
Motion Equation ◽  
Non Linear ◽  
Acoustic Emission Test

Leak detection is one of the most important problems in the oil and gas pipelines. Where it can lead to financial losses, severe human and environmental impacts. Acoustic emission test is a new technique for leak detection. Leakage in high pressure pipes creates stress waves resulting from localized loss of energy. Stress waves are transmitted through the pipe wall which will be recorded by using acoustic sensor or accelerometer installed on the pipe wall. Knowledge of how the pipe wall vibrates by acoustic emission resulting from leakage is a key parameter for leak detection and location. In this paper, modeling of pipe vibration caused by acoustic emission generated by escaping of fluid has been done. Donnells non linear theory for cylindrical shell is used to deriving of motion equation and simply supported boundary condition is considered. By using Galerkin method, the motion equation has been solved and a system of non linear equations with 6 degrees of freedom is obtained. To solve these equations, ODE tool of MATLAB software and Rung-Kuta numerical method is used and pipe wall radial displacement is obtained. For verification of this theory, acoustic emission test with continues leak source has been done. Vibration of wall pipe was recorded by using acoustic emission sensors. For better analysis, Fast Fourier Transform (FFT) was taken from theoretical and experimental results. By comparing the results, it is found that the range of frequencies which carried the most amount of energy is same which expresses the affectivity of the model.

scholarly journals Non-linear modelling and statistical anlaysis of multi-stage high-pressure inactivation of lactic acid bacteria

PAMM ◽  
2005 ◽  
Vol 5 (1) ◽  
pp. 673-674
Author(s):  
Klaus Valentin Kilimann ◽  
Christoph Hartmann ◽  
Michael Gänzle ◽  
Antonio Delgado
Keyword(s):  
High Pressure ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Multi Stage ◽  
Linear Modelling ◽  
Non Linear

New Design Basis for the Design of High Pressure Polyethylene Reactor Bay Using an Explosion Risk Analysis and Non Linear Finite Analysis

2010 ◽  
Author(s):  
Christophe Catala ◽  
Cedric Allemand ◽  
Michel Moine ◽  
Laurent Paris ◽  
Nicolas Salau¨n ◽  
...  
Keyword(s):  
High Pressure ◽  
Risk Analysis ◽  
Detection Efficiency ◽  
Atmospheric Dispersion ◽  
Concrete Wall ◽  
Element Analysis ◽  
Non Linear ◽  
Explosion Overpressure ◽  
High Pressure Polyethylene ◽  
Explosion Risk

High pressure technology used for the production of Low Density Polyethylene (LDPE) requires a particularly high degree of safety to protect both reactor and surroundings from an accidental event. For this reason, historically, such tubular reactors have been enclosed in roofless bunkers designed on empirical data. Recent improvement in production capacities, scientific knowledge and calculation tools now allows historic designs of these concrete structures to be challenged. The study we have conducted has offered a better understanding of the mechanisms involved in case of an accidental release of ethylene (ventilation and atmospheric dispersion conditions, gas detection efficiency) and subsequent explosion inside the reactor bay (maximum overpressure, impulsion duration, etc…). The methodology, using a combination of an explosion risk analysis (with help of 3D CFD tool) and a non linear finite element analysis (NLFEA) calculation tool has made it possible to define a clear and new basis of design for the enclosure walls to explosion overpressure loads. This in turn also offers new possibilities for an optimisation of the concrete wall thickness and design.

High-pressure insulating phase of Mo4O11 with collapsed volume

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
Z. Y. Liu ◽  
P. F. Shan ◽  
K. Y. Chen ◽  
Madalynn Marshall ◽  
S. Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Insulating Phase

Development of cavitation and enhanced injector models for diesel fuel injection system simulation

2002 ◽  
Vol 216 (7) ◽  
pp. 607-618 ◽  
Author(s):  
H-K Lee ◽  
M F Russell ◽  
C S Bae ◽  
H D Shin
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Diesel Fuel ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Injection System ◽  
Fuel Injection System ◽  
Non Linear ◽  
Diesel Fuel Injection ◽  
Injection Pressures

To expedite the application of fuel injection equipment to diesel engines, powertrain engineers are simulating the rate of injection with computer models. Many of the simple models give quite substantial errors if fuel cavitation in the high pressure system and the variations in bulk modulus with temperature and pressure are not included. This paper discuses cavitation and a companion paper discusses the treatment of non-linear bulk modulus. Diesel fuel injection nozzle hole size has been reduced and the injection pressures have been raised, to improve combustion, and the termination of the injection has been accelerated, to reduce carbon particle mass in the exhaust. High injection pressures and rapid termination set up very large hydraulic waves in the pipes and drillings of the fuel injection system, be it pump-pipe-nozzle or accumulator/common rail in type. The fuel momentum generated in these vigorous wave actions leaves such low pressures in parts of the system that vapour bubbles form in the fuel. Cavitation changes the bulk modulus of the fuel and the collapse of the cavities imparts sudden high pressure pulses to the fuel columns in the system and changes injection characteristics significantly. When modelling devices to control injection rate, the cavitation and non-linear bulk modulus have to be incorporated into the model. To this end, the concept of ‘condensation’ has been useful. The cavitated pipe section is divided into liquid and liquid + vapour mixture columns and modified momentum and mass conservation equations are applied separately. The model has been validated with a particular application of a rotary distributor pump to a high speed direct injection diesel engine, which is one of the more difficult fuel injection systems to model in which cavitation occurs at several operating conditions. The simulation results show the cavitation characteristics very well. This cavitated flow calculation model may be applied to other one-dimensional flow systems In addition, a more comprehensive injector model is introduced, which considers two loss factors at the needle seat and holes, sac volume, and viscous drag and leakage. This enhanced injector model shows some improvement at low load conditions

scholarly journals Lateral Buckling Induced by Trawl Gears Pull-Over Loads on High Temperature/High Pressure Subsea Pipeline

2012 ◽  
Author(s):  
Iswan Herlianto ◽  
Qiang Chen ◽  
Daniel Karunakaran
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Fe Analysis ◽  
Commercial Fishing ◽  
Lateral Buckling ◽  
External Interference ◽  
Global Response ◽  
Subsea Pipeline ◽  
Non Linear ◽  
Temperature And Pressure

Lateral buckling has become a challenge to deep water and high pressure/high temperature (HP/HT) flowlines. In areas that support major commercial fishing industries (e.g. the North Sea in Norway and Atlantic Margin in UK), there is high possibility of interaction between flowlines and fishing trawl gears. This interaction can expose the flowlines to substantial loads and induce lateral buckling. This paper presents global response of subsea pipeline as a result of trawl gear pull-over loads. The external interference from trawl gear pull-over loads can create substantial imperfection or out-of-straightness on the pipeline and may also generate global lateral buckling. The pull-over loads can also induce excessive bending moments and strains in the buckle region. To be able to understand the global response of the pipeline under pull-over loading conditions, a Finite Element (FE) analysis is carried out based on DNV OS F101 [1], DNV RP F110 [2] and DNV RP F111 [3] using general FE analysis software ANSYS v13. Non-linear transient analysis is used to incorporate the non-linear effects, such as the pipeline material nonlinearity, and the response of a structure under the action of pull-over time-dependent loads [8]. The FE analysis covers two periods of duration, i.e. during pull-over duration and post pull-over duration. The analysis during pull-over duration deals with the pipeline global response as a result of trawl gear pull-over loads. The pipeline is subjected to substantial horizontal and vertical pull-over forces from the trawl gear. For post pull-over duration, the FE analysis was carried out for an additional five seconds. In this period, the pull-over loads are no longer applied. However, the pipeline may expand further due to temperature and pressure loads on pipeline. The FE analysis result shows that the pull-over loads induce out-of-straightness on the pipeline and may cause lateral buckling. The pipeline deforms laterally at the pull-over location. The DNV displacement condition code check is used to check the integrity of the pipeline. The pipeline may in the risk under the trawl gears pull-over loads. This paper also shows the development of lateral buckling on the pipeline under different magnitudes of trawl gear pullover loads and lateral soil frictions. Further work should also take into account different dimension of pipeline, as the variation of operating temperature and pressure and variation of lateral and axial soil friction combinations to obtain better conclusions.

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