Sloshing in LNG Tanks: Assessment of High and Low Pressures

2008 ◽  
Author(s):  
Sebastian Schreier ◽  
Mathias Paschen
Keyword(s):  
High Pressure ◽  
Numerical Simulations ◽  
Liquid Sloshing ◽  
Pressure Impact ◽  
Membrane Type ◽  
Low Pressures

In the assessment of 2D numerical simulations of liquid sloshing in partially filled membrane-type cargo tanks of LNG Carriers high pressure impacts and also particularly low pressures have been identified. One high pressure impact at low filling levels and one sloshing impact leading to particularly low pressures at high filling levels are studied in greater detail. The results of these investigations are presented and conclusions are drawn with respect to the underlying physics of the two phenomena.

Experimental and Numerical Study on Pressure Losses and Flow Fluctuations in a High-Pressure Valve Assembly of Steam Turbine Governing System

2020 ◽  
Author(s):  
Vaclav Slama ◽  
Lukas Mrozek ◽  
Bartolomej Rudas ◽  
David Simurda ◽  
Jindrich Hala ◽  
...  
Keyword(s):  
High Pressure ◽  
Flow Field ◽  
Numerical Simulations ◽  
Pressure Loss ◽  
Operational Reliability ◽  
Operating Conditions ◽  
The Real ◽  
Pressure Losses ◽  
Flow Fluctuations ◽  
Valve Assembly

Abstract Aerodynamic measurements and numerical simulations carried out on a model of a high-pressure valve assembly used for nozzle governing of a turbine with 135MW output are described in this paper. Aim of the study is to investigate effects of control valve’s strainers on pressure losses and unsteadiness in the flow field. It is an important task since undesirable flow fluctuations can lead to operational reliability issues. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences (IT) where an aerodynamic tunnel is installed. Numerical simulations were carried out in the Doosan Skoda Power (DSP) Company using ANSYS software tools. The experimental model consists of one of two identical parts of the real valve assembly. It means it consists of an inlet pipeline, a stop valve, a valve chamber with two independent control valves, its diffusers and outlet pipelines. The numerical model consists of both assembly parts and includes also an A-wheel control stage in order to simulate the real turbine operating points. The different lifts of the main cone in each control valve for its useful combinations were investigated. Results were evaluated on the model with control valve’s strainers, which were historically used in order to stabilize the flow, and without them. The results of the experimental measurement were compared with the numerical results in the form of pressure losses prediction. From measured pressure fluctuations, it was found out where and for which conditions a danger of flow instabilities occurs. It can be concluded that there is a border, in terms of operating conditions, where the flow field starts to be unstable and this border is different dependent of the fact whether the control valve’s strainers are used or not. Therefore, the areas of safe and danger operational reliability can be predicted. The influence of the control valve’s strainers on the maximal amplitude of periodic fluctuations appears only for the cases when valves are highly overloaded. For normal operating conditions, there is no difference. As a result, the control valve’s strainers do not have to be used in standard applications of valve assemblies. Furthermore, a loss model for valve pressure loss estimation could be updated. Therefore, a pressure loss should be predicted with a sufficient accuracy for each new turbine bid with similar valve assemblies.

Some Numerical Simulations and an Experimental Investigation of a Finger Seal

2005 ◽  
Author(s):  
Minel J. Braun ◽  
Hazel M. Pierson ◽  
Hongmin Li
Keyword(s):  
Experimental Investigation ◽  
High Pressure ◽  
Pressure Drop ◽  
Numerical Simulations ◽  
Mechanical Performance ◽  
Low Pressure ◽  
Pressure Differential ◽  
Experimental Results ◽  
Axial Pressure ◽  
Brush Seals

Finger seals (FS) are compliant seal configurations. Unlike brush seals, they exhibit hydrodynamic lifting capabilities which allow non-contact sealing between stationary and rotating members. The compliance combined with the non-contacting feature allows both axial and radial adjustment of the seal to the rotor excursions without endangering the integrity of the former. The embodiment of a two-layer finger seal with high pressure (1c) and low pressure (1b) laminates is shown in Figure1. In this paper we shall analyze the thermo-hydraulic and mechanical performance (axial and radial deformations and displacements) of a representative repetitive cell that contains four high pressure and four low-pressure fingers arranged axially in a staggered configuration, and subject to rotation and an axial pressure drop. We shall also present experimental results pertaining to the seal deformation under axial pressure differential and rotation.

scholarly journals Venturi Wet Gas Flow Modeling Based on Homogeneous and Separated Flow Theory

2008 ◽  
Vol 2008 ◽  
pp. 1-25 ◽  
Author(s):  
Fang Lide ◽  
Zhang Tao ◽  
Xu Ying
Keyword(s):  
High Pressure ◽  
Pressure Drop ◽  
Gas Flow ◽  
Flow Model ◽  
Separated Flow ◽  
Flow Theory ◽  
Low Pressure ◽  
New Correlation ◽  
Wet Gas ◽  
Low Pressures

When Venturi meters are used in wet gas, the measured differential pressure is higher than it would be in gas phases flowing alone. This phenomenon is called over-reading. Eight famous over-reading correlations have been studied by many researchers under low- and high-pressure conditions, the conclusion is separated flow model and homogeneous flow model performing well both under high and low pressures. In this study, a new metering method is presented based on homogeneous and separated flow theory; the acceleration pressure drop and the friction pressure drop of Venturi under two-phase flow conditions are considered in new correlation, and its validity is verified through experiment. For low pressure, a new test program has been implemented in Tianjin University’s low-pressure wet gas loop. For high pressure, the National Engineering Laboratory offered their reports on the web, so the coefficients of the new proposed correlation are fitted with all independent data both under high and low pressures. Finally, the applicability and errors of new correlation are analyzed.

Effect of Heat Flux on Droplet Entrainment Using Annular Flow Dryout Model

2010 ◽  
Author(s):  
Masroor Ahmad ◽  
Evgeniy Burlutskiy ◽  
Simon P. Walker ◽  
Geoffrey F. Hewitt
Keyword(s):  
Experimental Data ◽  
Heat Flux ◽  
High Pressure ◽  
Liquid Film ◽  
Annular Flow ◽  
High Pressures ◽  
Droplet Entrainment ◽  
Annular Film ◽  
Low Pressures ◽  
Flow Experiments

Annular film dryout depends upon the competition of entrainment, deposition and evaporation processes between the droplet-laden core and wall liquid film. In this paper, effect of heat flux on droplet entrainment is analyzed by modeling different low and high pressure diabatic annular flow experiments numerically using an annular flow dryout model (AFM). Overall, the AFM predicted the experimental data reasonably accurately. It is concluded that at high pressures increasing heat flux may enhance net entrainment considerably but this effect diminishes at low pressures.

scholarly journals Experimental and Numerical Investigation of Phase Separation due to Multi-Component Mixing at High-Pressure Conditions

2017 ◽  
Author(s):  
Christoph Traxinger ◽  
Hagen Müller ◽  
Michael Pfitzner ◽  
Steffen Baab ◽  
Grazia Lamanna ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Separation ◽  
Numerical Simulations ◽  
A Priori ◽  
Two Phase ◽  
Separation Processes ◽  
Pure Nitrogen ◽  
Elastic Light Scattering ◽  
Large Eddy ◽  
High Pressure Injection

Experiments and numerical simulations were carried out in order to contribute to a better understanding and predic-tion of high-pressure injection into a gaseous environment. Specifically, the focus was put on the phase separation processes of an initially supercritical fluid due to the interaction with its surrounding. N-hexane was injected into a chamber filled with pure nitrogen at 5 MPa and 293 K and three different test cases were selected such that they cover regimes in which the thermodynamic non-idealities, in particular the effects that stem from the potential phase separation, are significant. Simultaneous shadowgraphy and elastic light scattering experiments were conducted to capture both the flow structure as well as the phase separation. In addition, large-eddy simulations with a vapor- liquid equilibrium model were performed. Both experimental and numerical results show phase formation for the cases, where the a-priori calculation predicts two-phase flow. Moreover, qualitative characteristics of the formation process agree well between experiments and numerical simulations and the transition behaviour from a dense-gasto a spray-like jet was captured by both.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4756

scholarly journals Effects of Composition, Pressure, and Temperature on the Elastic Properties of SiO2–TiO2 Glasses: An Integrated Ultrasonic and Brillouin Study

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 481
Author(s):  
Murli H. Manghnani ◽  
Quentin Williams ◽  
Teruyuki Matsui ◽  
Peter C. Schultz ◽  
Charles R. Kurkjian
Keyword(s):  
High Pressure ◽  
Elastic Properties ◽  
Excellent Agreement ◽  
Diamond Anvil Cell ◽  
Brillouin Scattering ◽  
Elastic Behavior ◽  
Tio2 Content ◽  
Diamond Anvil ◽  
Raman Study ◽  
Low Pressures

We have systematically investigated the elastic properties (ρ, VP, VS, K, μ and σ) of eight SiO2–TiO2 glasses, varying in composition from 1.3 to 14.7 wt% TiO2, as a function of pressure up to 0.5 GPa by the pulse superposition (PSP) ultrasonic technique, and two compositions (1.3 and 9.4 wt% TiO2) up to ~5.7 GPa by Brillouin scattering in a diamond anvil cell. The parameters were also measured after annealing to 1020 °C. Composition–elasticity relationships, except for K and σ, are more or less linear; the annealing simply makes the relationships more uniform (less scatter). There is excellent agreement between the ultrasonic and Brillouin measurements at ambient and high pressure. The pressure-induced anomalous elastic behavior (negative dVP/dP and dK/dP) becomes more negative (more compressible) with the increasing TiO2 content. Correspondingly, the acoustic Grüneisen parameters become more negative with increases in the TiO2 content, reaching a minimum near ~8–10 wt% TiO2. The comparison of the low- and high-pressure ultrasonic and Brillouin VP and VS in two glasses (1.3 and 9.4 wt% TiO2) shows excellent agreement, defining the reversible elastic behavior at low pressures and irreversible behavior at higher pressures (≥5.7 GPa) well. This result is consistent with our previous high-pressure Raman study showing an irreversible structural change in a similar pressure range.

scholarly journals High Pressure Impact Forming of Titanium Carbide Cermet

1970 ◽  
Vol 17 (4) ◽  
pp. 176-178
Author(s):  
Katsuya Kudaka ◽  
Naoto Asami ◽  
Takashi Ishimori
Keyword(s):  
High Pressure ◽  
Titanium Carbide ◽  
Pressure Impact

Investigation of species-mass diffusion in binary-species boundary layers at high pressure using direct numerical simulations

2021 ◽  
Vol 928 ◽  
Author(s):  
Takahiko Toki ◽  
Josette Bellan
Keyword(s):  
High Pressure ◽  
Numerical Simulations ◽  
Boundary Layers ◽  
Mass Flux ◽  
Mass Fraction ◽  
Soret Effect ◽  
Streamwise Velocity ◽  
Mass Diffusion ◽  
Direct Numerical Simulations ◽  
Temperature Fields

Direct numerical simulations of single-species and binary-species temporal boundary layers at high pressure are performed with special attention to species-mass diffusion. The working fluids are nitrogen or a mixture of nitrogen and methane. Mean profiles and turbulent fluctuations of mass fraction show that their qualitative characteristics are different from those of streamwise velocity and temperature, due to the different boundary conditions. In a wall-parallel plane near the wall, the streamwise velocity and temperature have streaky patterns and the fields are similar. However, the mass fraction field at the same location is different from the streamwise velocity and temperature fields indicating that species-mass diffusion is not similar to the momentum and thermal diffusion. In contrast, at the centre and near the edge of the boundary layer, the mass fraction and temperature fields have almost the same pattern, indicating that the similarity between thermal and species-mass diffusion holds away from the wall. The lack of similarity near the wall is traced to the Soret effect that induces a temperature-gradient-dependent species-mass flux. As a result, a new phenomenon has been identified for a non-isothermal binary-species system – uphill diffusion, which in its classical isothermal definition can only occur for three or more species. A quadrant analysis for the turbulent mass flux reveals that near the wall the Soret effect enhances the negative contributions of the quadrants. Due to the enhancement of the negative contributions, small species-concentration fluid tends to be trapped near the wall.

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