scholarly journals Microflow Leakage Through the Clearance of a Metal-Metal Seal

2016 ◽  
Author(s):  
Ali A. Anwar ◽  
Konstantinos Ritos ◽  
Yevgen Gorash ◽  
William Dempster ◽  
David Nash
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Low Pressure ◽  
Channel Height ◽  
Relief Valve ◽  
Pressure Relief ◽  
Metal Seal ◽  
Metal Metal ◽  
Representative Model ◽  
Flow Through

The motivation behind this study is to simulate high pressure gas flow through the clearance between a valve seat and disc when in a closed position using a representative model. This leakage phenomenon is common in metal-to-metal seal pressure relief valves. As a pressure relief valve reaches the set pressure, it is known for the leakage to increase. The representative model that we studied is of an ideal-gas flow through a 2D microchannel in the slip flow regime. We used a laminar continuum flow solver which solved the mass, momentum and energy equations. In addition, we applied low pressure slip boundary conditions at the wall boundaries which considered Maxwells model for slip. The channel height was varied from 1μm to 5μm while the length remained at 1.25 mm, this means the length to height ratio varied from 1250 to 250. Inlet pressure was varied from a low pressure (0.05 MPa) to a high pressure (18.6 MPa), while the outlet remained constant at atmospheric. The calculated mass flow rate is compared to an analytical solution giving very good agreement for low pressure ratios and high length to height ratios.

INVESTIGATION OF THE TIME OF GAS FLOW THROUGH A HOLE IN LONG PIPELINES UNDER HIGH PRESSURE

2020 ◽  
Vol 58 (1) ◽  
pp. 30-43
Author(s):  
N.D. Yakimov ◽  
◽  
A.I. Khafizova ◽  
N.D. Chichirova ◽  
O.S. Dmitrieva ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Flow Through

The Influence of Different Rim Seal Geometries on Hot-Gas Ingestion and Total Pressure Loss in a Low-Pressure Turbine

2010 ◽  
Author(s):  
P. Schuler ◽  
W. Kurz ◽  
K. Dullenkopf ◽  
H.-J. Bauer
Keyword(s):  
Pressure Loss ◽  
Total Pressure ◽  
Gas Flow ◽  
Low Pressure ◽  
Total Pressure Loss ◽  
Pressure Loss Coefficient ◽  
Low Pressure Turbine ◽  
Hot Gas ◽  
Flow Through ◽  
Total Pressure Loss Coefficient

In order to prevent hot-gas ingestion into the rotating turbo machine’s inside, rim seals are used in the cavities located between stator- and rotor-disc. The sealing flow ejected through the rim seal interacts with the boundary layer of the main gas flow, thus playing a significant role in the formation of secondary flows which are a major contributor to aerodynamic losses in turbine passages. Investigations performed in the EU project MAGPI concentrate on the interaction between the sealing flow and the main gas flow and in particular on the influence of different rim seal geometries regarding the loss-mechanism in a low-pressure turbine passage. Within the CFD work reported in this paper static simulations of one typical low-pressure turbine passage were conducted containing two different rim seal geometries, respectively. The sealing flow through the rim seal had an azimuthal velocity component and its rate has been varied between 0–1% of the main gas flow. The modular design of the computational domain provided the easy exchange of the rim seal geometry without remeshing the main gas flow. This allowed assessing the appearing effects only to the change of rim seal geometry. The results of this work agree with well-known secondary flow phenomena inside a turbine passage and reveal the impact of the different rim seal geometries on hot-gas ingestion and aerodynamic losses quantified by a total pressure loss coefficient along the turbine blade. While the simple axial gap geometry suffers considerable hot-gas ingestion upstream the blade leading edge, the compound geometry implying an axial overlapping presents a more promising prevention against hot-gas ingestion. Furthermore, the effect of rim seals on the turbine passage flow field has been identified applying adequate flow visualisation techniques. As a result of the favourable conduction of sealing flow through the compound geometry, the boundary layer is less lifted by the ejected sealing flow, thus resulting in a comparatively reduced total pressure loss coefficient over the turbine blade.

Transient Analysis of Dedicated Pressure Relief Valve Under High-Pressure Condition in Severe Accident for Tianwan 56 Nuclear Power Plant

2020 ◽  
Author(s):  
Youyou Xu ◽  
Jian Deng ◽  
Xiaoji Wang ◽  
Lingjun Wu ◽  
Ming Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
Power Plant ◽  
Nuclear Power ◽  
Severe Accident ◽  
Feed Water ◽  
Pressure Condition ◽  
Relief Valve ◽  
Pressure Relief ◽  
Accident Sequences ◽  
Water Accident

Abstract In the management of severe accident of nuclear reactor, the pressure relief of reactor coolant system (RCS) is an important mitigation measure to prevent high pressure core melt (HPCM). In the safety system improvement of Tianwan56 nuclear power plant, the optimization measure of adding the dedicated pressure relief valve (DPRV) for severe accident were adopted. This improvement allows the reactor to release the pressure of RCS before the reactor vessel being damaged to mitigate the consequence of reactor melt accident under high-pressure condition. Based on the analysis of severe accident sequences, the total loss of feed water accident is confirmed to cover the various severe accident consequences which may lead to HPCM accident. This paper studied the transient characteristics of total loss of feed water accident sequences, and the factors such as valve opening delay on the operating temperature of the valve were researched. Finally, the representative and envelope operating condition of DPRV under severe accident was clarified. Besides, the temperature curve of fluid passing through the valve and the maximum temperature the valve experienced were obtained. This research provides the valuable and indispensable basis to the operability and integrity analysis of DPRV in severe accident.

Low‐pressure gas flow through a microsize channel

1982 ◽  
Vol 53 (4) ◽  
pp. 2904-2909 ◽  
Author(s):  
Bernard E. Kalensher ◽  
Julius Perel
Keyword(s):  
Gas Flow ◽  
Low Pressure ◽  
Flow Through

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.

A Numerical Study of High Pressure Flow Through a Hydraulic Pressure Relief Valve Considering Pressure and Temperature Dependent Viscosity, Bulk Modulus and Density

2016 ◽  
Author(s):  
Sven Osterland ◽  
Jürgen Weber
Keyword(s):  
High Pressure ◽  
Bulk Modulus ◽  
Hydraulic Pressure ◽  
Temperature Dependent ◽  
Relief Valve ◽  
Temperature Dependent Viscosity ◽  
Pressure Region ◽  
Flow Through ◽  
The Mean ◽  
Dependent Viscosity

This paper investigates the flow through a hydraulic pressure relief valve at high levels of operating pressure up to 700 bar (10000 Psi). Following the flow path from the cold high pressure region before the metering edge to the warm low pressure region behind, the mean viscosity decreases by a factor of 16, the mean bulk modulus decreases by a factor of 2 and the mean density decreases by 6 %. Based on this preliminary considerations, a turbulent single phase flow considering pressure and temperature dependent viscosity, bulk modulus and density is modelled and steady state as well as transient calculations are performed. The results of this study show that a pressure and temperature dependent viscosity reduces the pressure drop and the spool force by 10 % compared to a simulation with constant fluid parameters. Moreover, it is shown that compressible flow modelling has negligible influence on pressure drop and spool force — nevertheless, it is required to describe the temperature correctly. Due to the effect of volumetric work an incompressible model approach predicts the mean temperature rise 20 % too high. Finally, it was found that the temperature on the spool exceeds 400 °C. Afterwards, this fact is experimentally validated obtaining tempering colors in high pressure tests.

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