The Expansion and Drainage Characteristics of AFFF in Low-Pressure Environment

2017 ◽  
Author(s):  
Qiang Sun ◽  
Quanyi Liu ◽  
Xiantao Chen ◽  
Mingwu Wang ◽  
Yuanhua He
Keyword(s):  
Combustion Chamber ◽  
Ambient Pressure ◽  
Low Pressure ◽  
Expansion Ratio ◽  
Experimental Results ◽  
Lower Pressure ◽  
Drainage Time ◽  
Measuring Cylinder ◽  
Film Forming ◽  
Drainage Ratio

Tests are conducted in a low-pressure combustion chamber of 3 × 2 × 4.65m3 in volume to investigate the effect of low pressure on the drainage and expansion characteristics of AFFF (Aqueous Film-Forming Foam). A manipulator equipment with the frequency of 4 Hz and the amplitude of 32cm is designed for the foaming of AFFF in the chamber. The parameters of expansion and drainage ratio are obtained under two different ambient pressure of 101kPa and 30kPa. Two fluorocarbon surfactants contained commercial AFFF (AFFF1 is type of 3% and AFFF2 is the type of 6%) that were used in precious studies are both diluted into different quality percentage resolutions, and then achieve foaming in a 130ml measuring cylinder with a cone bottom. The foaming expansion ratio and drainage time are obtained based on the recorded videos. Experimental results show that the expansion ratio of both AFFF1 and AFFF2 resolutions (the expansion ratio <6) is lower under the pressure of 30kPa than that under 101kPa. The drainage time (25% and 50%) of AFFF1 is increasing in the lower pressure environment. On the contrary, 50% drainage time of AFFF2 is shorter under 30kPa than that under 101kPa, but 25% drainage time of AFFF2 is almost the same under two ambient pressures. The variations under low pressure environment are obvious and various from each other, but the further tests should be conducted to reveal and explore the mechanism.

Unprecedented CO2 adsorption behaviour by 5A-type zeolite discovered in lower pressure region and at 300 K

2021 ◽  
Author(s):  
Akira Oda ◽  
Suguru Hiraki ◽  
Eiji Harada ◽  
Ikuka Kobayashi ◽  
Takahiro Ohkubo ◽  
...  
Keyword(s):  
Pressure Range ◽  
Co2 Adsorption ◽  
Low Pressure ◽  
Lower Pressure ◽  
Dft Studies ◽  
Adsorption Behaviour ◽  
Zeolite Sample ◽  
Pressure Region ◽  
Type Zeolite ◽  
Efficient Adsorbent

The NaCaA-85 zeolite sample which works as an efficient adsorbent for CO2 at RT and in low pressure range was found and its specificity is nicely explained by the model composed of CO2 pinned by two types of Ca2+ ions through far-IR and DFT studies.

scholarly journals Parametric diagnostics of the condition of a dual-flow turbojet engine using neural network simulation of the operating process

2018 ◽  
Vol 224 ◽  
pp. 02057
Author(s):  
Anas S. Gishvarov ◽  
Julien Celestin Raherinjatovo
Keyword(s):  
Neural Network ◽  
High Pressure ◽  
Combustion Chamber ◽  
Early Stage ◽  
Low Pressure ◽  
Similarity Criteria ◽  
Ann Model ◽  
Turbojet Engine ◽  
Operating Process ◽  
Pressure Compressor

The article presents a method of parametric diagnostics of the condition of a dual-flow turbojet engine (DFTE). The method is based on the identification (determination) of the condition of the DFTE components (the compressor, combustion chamber, turbine) with application of a mathematical model of the operating process which is presented as an artificial neural network (ANN) model. This model describes the relation between the monitored parameters of the DFTE (the air temperatures (Tlpc*, Thpc*) beyond the low pressure compressor (LPC) and the high pressure compressor (HPC), the pressure beyond the LPC (Plpc), the fuel consumption rate (Gf), the gas temperatures (Thpt*, Tlpt*) beyond the high pressure turbine (HPT) and the low pressure turbine (LPT)) and the parameters of the condition of its components (the efficiencies of the LPC and the HPC (ηlpc*, ηhpc*), the stagnation pressure recovery factor in the combustion chamber (σcc), the efficiencies of the HPT and the LPT (ηhpt*, ηlpt*)). The parameters of the condition of the engine components (ηlpc*, ηhpc*, σcc, ηhpt*, ηlpt*) are the similarity criteria (integral criteria) which enable to identify the condition of the DFTE components to a high degree of reliability. Such analysis enables to detect defects at an early stage, even if the values of the monitored parameters (Тlpc*, Тhpc*, Plpc, Gf, Тhpt*, Тlpt*) are within the permissible limits. We provide the sequence for development of the ANN model and the results of its performance study during the parametric diagnostics of the condition of the DFTE.

Effects of Fuel Nozzle Condition on Gas Turbine Combustion Chamber Exit Temperature Distributions

2010 ◽  
Author(s):  
Kristen Bishop ◽  
William Allan
Keyword(s):  
Combustion Chamber ◽  
Ambient Pressure ◽  
Cone Angle ◽  
Operating Conditions ◽  
Spray Cone Angle ◽  
Mixing Processes ◽  
Spray Cone ◽  
Temperature Distributions ◽  
Fuel Nozzle ◽  
Exit Temperature

The effects of fuel nozzle condition on the temperature distributions experienced by the nozzle guide vanes have been investigated using an optical patternator. Average spray cone angle, symmetry, and fuel streaks were quantified. An ambient pressure and temperature combustion chamber test rig was used to capture exit temperature distributions and to determine the pattern factor. The rig tests matched representative engine operating conditions by matching Mach number, equivalence ratio, and fuel droplet size. It was observed that very small deviations (± 10° in spray cone angle) from a nominal distribution in the fuel nozzle spray pattern correlated to increases in pattern factor, apparently due to a degradation of mixing processes, which created larger regions of very high temperature core flow and smaller regions of cooler temperatures within the combustion chamber exit plane. The spray cone angle had the most measureable influence while the effects of spray roundness and streak intensity had slightly less influence. Comparisons were made with published studies conducted on the combustion chamber geometry, and recommendations were made for fuel nozzle inspections.

The Influence of Ambient Pressure on the Dynamic Response of RF MEMS Switches

2010 ◽  
Author(s):  
Avihay Ohana ◽  
Oren Aharon ◽  
Ronen Maimon ◽  
Boris Nepomnyashchy ◽  
Lior Kogut
Keyword(s):  
Rf Mems ◽  
Ambient Pressure ◽  
Actuation Voltage ◽  
Operating Conditions ◽  
Experimental Results ◽  
Release Time ◽  
Q Factor ◽  
Optimal Operating ◽  
Mems Switches ◽  
Rf Mems Switches

A study of the dynamic behavior of an RF MEMS switch is presented at different operating conditions. Experimental results for the actuation and release time and Q-factor as a function of the ambient pressure and actuation voltage are compared to theoretical predictions based on existing model. Optimal operating conditions (ambient pressure and actuation voltage) are determined based on two criterions: minimal actuation and release time and minimal oscillations upon switch release. In light of the experimental results optimal operating conditions determined to be 1.4Vpi at a pressure of a few torrs where actuation and release time are equal and short enough with no release oscillations. Three pressure regimes are identified with characteristic behavior of the Q-factor and actuation and release time in each regime. These behaviors have significant implications in many MEMS devices, especially RF MEMS switches.

scholarly journals Assessment of Severe Accident Management for Small IPWR under an ESBO Scenario

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Hao Yu ◽  
Minjun Peng
Keyword(s):  
High Pressure ◽  
Low Pressure ◽  
Lower Pressure ◽  
Severe Accident ◽  
Maximum Temperature ◽  
Pressurized Water ◽  
The Core ◽  
Severe Accidents ◽  
Accident Management ◽  
Degradation Studies

Interest in evaluation of severe accidents induced by extended station blackout (ESBO) has significantly increased after Fukushima. In this paper, the severe accident process under the high and low pressure induced by an ESBO for a small integrated pressurized water reactor (IPWR)-IP200 is simulated with the SCDAP/RELAP5 code. For both types of selected scenarios, the IP200 thermal hydraulic behavior and core meltdown are analyzed without operator actions. Core degradation studies firstly focus on the changes in the core water level and temperature. Then, the inhibition of natural circulation in the reactor pressure vessel (RPV) on core temperature rise is studied. In addition, the phenomena of core oxidation and hydrogen generation and the reaction mechanism of zirconium with the water and steam during core degradation are analyzed. The temperature distribution and time point of the core melting process are obtained. And the IP200 severe accident management guideline (SAMG) entry condition is determined. Finally, it is compared with other core degradation studies of large distributed reactors to discuss the influence of the inherent design characteristics of IP200. Furthermore, through the comparison of four sets of scenarios, the effects of the passive safety system (PSS) on the mitigation of severe accidents are evaluated. Detailed results show that, for the quantitative conclusions, the low coolant storage of IP200 makes the core degradation very fast. The duration from core oxidation to corium relocation in the lower-pressure scenario is 53% faster than that of in the high-pressure scenario. The maximum temperature of liquid corium in the lower-pressure scenario is 134 K higher than that of the high-pressure scenario. Besides, the core forms a molten pool 2.8 h earlier in the lower-pressure scenario. The hydrogen generated in the high-pressure scenario is higher when compared to the low-pressure scenario due to the slower degradation of the core. After the reactor reaches the SAMG entry conditions, the PSS input can effectively alleviate the accident and prevent the core from being damaged and melted. There is more time to alleviate the accident. This study is aimed at providing a reference to improve the existing IPWR SAMGs.

Laser ignition of an experimental combustion chamber with a multi-injector configuration at low pressure conditions

2017 ◽  
Vol 9 (3) ◽  
pp. 299-311 ◽  
Author(s):  
Michael Börner ◽  
Chiara Manfletti ◽  
Gerhard Kroupa ◽  
Michael Oschwald
Keyword(s):  
Combustion Chamber ◽  
Low Pressure ◽  
Laser Ignition ◽  
Experimental Combustion

THERMAL CHARACTERISTICS OF FOAMS AND DISCHARGE FROM FIRE-EXTINGUISHMENT FOAM SPRAY NOZZLE

2009 ◽  
Vol 23 (03) ◽  
pp. 381-384
Author(s):  
YOUN-JEA KIM ◽  
JIN-SOO PYO
Keyword(s):  
Heat Flux ◽  
Temperature Gradient ◽  
Thermal Characteristics ◽  
Expansion Ratio ◽  
Experimental Results ◽  
Orifice Diameter ◽  
Spray Nozzle ◽  
Foam Expansion ◽  
Fire Extinguishment ◽  
Air Hole

To evaluate the performance of discharged foam agents used to protect structures from heat and fire damages, the thermal characteristics of fire-extinguishment foams were experimentally investigated. Especially, two different parameters of a spray nozzle, that is, the number of air holes and the orifice diameter, were considered. A simple repeatable test for fire-extinguishment foams subjected to fire radiation was performed. Experimental results showed that the expansion ratio of the discharged foam with the small orifice throat ( d 0= 9.5 mm ) and opened air hole ( N h =9) was large. Results also showed that although the temperature gradient in the foam increased as the foam expansion ratio is increased, it remained constant as the intensity of heat flux increased.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

Prediction of Reynolds Number Effects on Low-Pressure Turbines Using a High-Order ILES Method

2019 ◽  
Author(s):  
Marc Bolinches-Gisbert ◽  
David Cadrecha Robles ◽  
Roque Corral ◽  
Fernando Gisbert
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Fourth Order ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
High Order ◽  
Experimental Results ◽  
Numerical Code ◽  
Design System

Abstract A comprehensive comparison between Implicit Large Eddy Simulations (ILES) and experimental results of a modern highlift low-pressure turbine airfoil has been carried out for an array of Reynolds numbers (Re). Experimental data were obtained in a low-speed linear cascade at the Polithecnic University of Madrid using hot-wire anemometry and LDV. The numerical code is fourth order accurate, both in time and space. The spatial discretization of the compressible Navier-Stokes equations is based on a high-order Flux Reconstruction approach while a fourth order Runge-Kutta method is used to march in time the simulations. The losses, pressure coefficient distributions, and boundary layer and wake velocity profiles have been compared for an array of realistic Reynolds numbers. Moreover, boundary layer and wake velocity fluctuations are compared for the first time with experimental results. It is concluded that the accuracy of the numerical results is comparable to that of the experiments, especially for integral quantities such as the losses or exit angle. Turbulent fluctuations in the suction side boundary layer and the wakes are well predicted also. The elapsed time of the is about 140 hours on 40 Graphics Processor Units. The numerical tool is integrated within an industrial design system and reuses pre- and post-processing tools previously developed for another kind of applications. The trend of the losses with the Reynolds number has a sub-critical regime, where the losses scale with Re−1, and a supercrital regime, where the losses scale with Re−1/2. This trend can be seen both, in the simulations and the experiments.

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