Evaluating the Effects of Sealing Quality on Gas Leakage Rates During Structural Fumigation by Pressurization Testing and CFD Simulations

2010 ◽  
Vol 53 (3) ◽  
pp. 853-861 ◽  
Author(s):  
W. Chayaprasert ◽  
D. E. Maier
Keyword(s):  
Cfd Simulations ◽  
Gas Leakage ◽  
Structural Fumigation

Modelling of Sonic Jets for Gas Leak Applications

2019 ◽  
Author(s):  
Stefano Minotti ◽  
Alessandro Corsini ◽  
Giovanni Delibra ◽  
Gabriele Lucherini ◽  
Stefano Rossin ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Ventilation System ◽  
Supersonic Jet ◽  
Cfd Simulations ◽  
Fuel Gas ◽  
Safety Issues ◽  
Gas Leakage ◽  
Round Jets ◽  
Gas Leak ◽  
Gas System

Abstract Design of gas turbine packages is subjected to safety issues and the related guidelines are provided by ISO-21789. According to this code, the ventilation system shall guarantee a good and safe dilution in case of an unexpected gas leakage from components of the fuel gas system inside the enclosure. The evaluation of the dilution is commonly carried out by CFD simulations and the ISO-21789 indicates the criteria to evaluate the danger of a gas leak by estimating the cloud volume of the explosive mixture. To follow this prescription and to properly calculate the exact volume cloud, it is fundamental to accurately reproduce the fuel gas leak, which is always a supersonic jet of fuel gas into an air-ventilated domain. The main criticality is to simulate a supersonic jet into a complex domain such as the gas turbine package, considering the industrial goals in terms of accuracy and time constraints. The complexity is due to the geometry of the package and to the multiple locations where the leakage could occur. In such context, it is preferable to develop an advanced modeling of the phenomenon rather than simply improve the detail of the CFD, that could turn out to be unfeasible for industrial goals. For this reason, the authors present a series of simulations of under-expanded jets at high pressure ratios carried out to investigate the applicability of the sonic source approach to not-round jets.

Extraperitoneal gas leakage causing pneumothorax after low rectal submucosal dissection

2019 ◽  
Vol 85 (5) ◽  
Author(s):  
Arantxa Pavón-Benito ◽  
Ana Casimiro-Erviti ◽  
Leonor Veiga-Gil ◽  
Elena Pérez-Bergara ◽  
Miguel Salvador-Bravo
Keyword(s):  
Gas Leakage ◽  
Submucosal Dissection

Gas leakage monitor and Controller

2020 ◽  
Vol 06 (02) ◽  
pp. 22-27
Author(s):  
Vidhya priya SP ◽  
Shiny Rachel M ◽  
Preethi R ◽  
Thiruvenketa kumar T
Keyword(s):  
Gas Leakage

Comparison of DSMC and CFD Models of Heat Transfer in a Rarefied Two-Dimensional Geometry

2018 ◽  
Author(s):  
Dilesh Maharjan ◽  
Mustafa Hadj-Nacer ◽  
Miles Greiner ◽  
Stefan K. Stefanov
Keyword(s):  
Heat Transfer ◽  
Rarefied Gas ◽  
Complex Geometry ◽  
Direct Simulation Monte Carlo ◽  
Accurate Method ◽  
Vacuum Drying ◽  
Helium Pressure ◽  
Two Dimensional ◽  
Dsmc Method ◽  
Cfd Simulations

During vacuum drying of used nuclear fuel (UNF) canisters, helium pressure is reduced to as low as 67 Pa to promote evaporation and removal of remaining water after draining process. At such low pressure, and considering the dimensions of the system, helium is mildly rarefied, which induces a thermal-resistance temperature-jump at gas–solid interfaces that contributes to the increase of cladding temperature. It is important to maintain the temperature of the cladding below roughly 400 °C to avoid radial hydride formation, which may cause cladding embrittlement during transportation and long-term storage. Direct Simulation Monte Carlo (DSMC) method is an accurate method to predict heat transfer and temperature under rarefied condition. However, it is not convenient for complex geometry like a UNF canister. Computational Fluid Dynamics (CFD) simulations are more convenient to apply but their accuracy for rarefied condition are not well established. This work seeks to validate the use of CFD simulations to model heat transfer through rarefied gas in simple two-dimensional geometry by comparing the results to the more accurate DSMC method. The geometry consists of a circular fuel rod centered inside a square cross-section enclosure filled with rarefied helium. The validated CFD model will be used later to accurately estimate the temperature of an UNF canister subjected to vacuum drying condition.

Recurrence Characteristics Analysis of Near-Surface Wind Speed Signal with Different Sampling Frequencies

2014 ◽  
Vol 599-601 ◽  
pp. 1605-1609 ◽  
Author(s):  
Ming Zeng ◽  
Zhan Xie Wu ◽  
Qing Hao Meng ◽  
Jing Hai Li ◽  
Shu Gen Ma
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Recurrence Plot ◽  
Sampling Frequency ◽  
Near Surface ◽  
Gas Leakage ◽  
Time Period ◽  
Characteristics Analysis ◽  
Quantification Analysis

The wind is the main factor to influence the propagation of gas in the atmosphere. Therefore, the wind signal obtained by anemometer will provide us valuable clues for searching gas leakage sources. In this paper, the Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA) are applied to analyze the influence of recurrence characteristics of the wind speed time series under the condition of the same place, the same time period and with the sampling frequency of 1hz, 2hz, 4.2hz, 5hz, 8.3hz, 12.5hz and 16.7hz respectively. Research results show that when the sampling frequency is higher than 5hz, the trends of recurrence nature of different groups are basically unchanged. However, when the sampling frequency is set below 5hz, the original trend of recurrence nature is destroyed, because the recurrence characteristic curves obtained using different sampling frequencies appear cross or overlapping phenomena. The above results indicate that the anemometer will not be able to fully capture the detailed information in wind field when its sampling frequency is lower than 5hz. The recurrence characteristics analysis of the wind speed signals provides an important basis for the optimal selection of anemometer.

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