scholarly journals Depressurization of Vertical Pipe with Temperature Gradient Modeled with WAHA Code

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Oriol Costa ◽  
Iztok Tiselj ◽  
Leon Cizelj

The subcooled decompression under temperature gradient experiment performed by Takeda and Toda in 1979 has been reproduced using the in-house code WAHA version 3. The sudden blowdown of a pressurized water pipe under temperature gradient generates a travelling pressure wave that changes from decompression to compression, and vice versa, every time it reaches the two-phase region near the orifice break. The pressure wave amplitude and frequency are obtained at different locations of the pipe's length. The value of the wave period during the first 20 ms of the experiment seems to be correct but the pressure amplitude is overpredicted. The main three parameters that contribute to the pressure wave behavior are: the break orifice (critical flow model), the ambient pressure at the outlet, and the number of volumes used for the calculation. Recent studies using RELAP5 code have reproduced the early pressure wave (transient) of the same experiment reducing the discharge coefficient and the bubble diameter. In the present paper, the long-term pipe pressure, that is, 2 seconds after rupture, is used to estimate the break orifice that originates the pressure wave. The numerical stability of the WAHA code is clearly proven with the results using different Courant numbers.

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Fang Yuan ◽  
Quanbin Zhao ◽  
Daotong Chong ◽  
Weixiong Chen

Steam discharged into subcooled water is investigated experimentally to demonstrate the direct contact condensation phenomena in nuclear reactor safety system and underwater propulsion apparatus. The steam jet condenses to various shapes at different thermal hydraulic conditions. A condensation regime diagram is drawn to classify the regime for different flow patterns, among which there are three typical shapes of steam plume characterizing the chugging, condensation oscillation, stable condensation regime (Figure 1). The flow region can be separated into three parts—vapor, water and two-phase regions, and the white patch in the image indicating the two-phase region is a mixture of condensed vapor and subcooled water. Three typical stages of bubble motions—growth (subimage 1 to 6, Figure 2), necking (subimage 7 to 10, Figure 2), and detachment (subimage 11 to 13, Figure 2)—are demonstrated. The bubble diameter reaches the maximum at the necking stage and remains approximately invariant with the connecting neck prolonging for a period. A series of sequent photos exhibits shape transformations at the stable condensation regime, implying that the steam plume grows and shortens periodically due to comprehensive effects of injection, viscosity damping and condensation (Figure 3). The dimensionless penetration length, defined as the ratio of penetration length to nozzle diameter, is in the range of 8.23–11.67 in the Figure 3. The majority of previous literatures present the average dimensionless penetration length which is closely related with time-averaged heat transfer characteristic. However, variations of steam plume are proven to account for pressure oscillation phenomena by the transient visualization investigations, in which the first dominant frequency acquired from the FFT domain graph of pressure signal is consistent with the period of steam plume variations. The second dominant frequency is verified to be caused by oscillations of detached bubbles (subimage 8 and 9, Figure 3) in the research.


2020 ◽  
Author(s):  
Haiquan Bi ◽  
Yi Fang ◽  
Yuanlong Zhou ◽  
Honglin Wang ◽  
Xu Zhang

Abstract The pressure wave is of crucial importance for subway development since it greatly influences the comfort while taking. As the subway lines are rapidly developing in the cities, the pressure wave in different subway tunnel constructures is urgently needed to be studied and receded. In this paper, a subway tunnel pressure wave experimental system was designed, constructed, and tested. The influence of train model head shape, train model speed, shaft number in the tunnel, and bypass number in the tunnel on the pressure wave amplitude were experimented with and analyzed. The results show that the train model head shapes significantly impact the amplitude of the initial compression wave in the tunnel. The blunter train model head generates a greater amplitude of the initial compression wave. When the train passes through a single-track tunnel, the maximum positive pressure amplitude of the pressure wave in the tunnel is at the first compression wave at the tunnel entrance. The maximum negative pressure value in the tunnel is at the superposition of the initial compression wave reflected from the first time and the train's body, which is related to the length of the train's body, tunnel length, train's speed, and sound speed. The shaft set in the tunnel decreases the amplitude of the initial compression wave in the tunnel space behind, but it will increase the pressure wave's amplitude reflected in the tunnel when the train passes through the shaft. After the bypass tunnel is added, the initial compression wave propagation in the tunnel behind the bypass tunnel is receded. Still, it also increases the negative pressure amplitude when the train passes.


2011 ◽  
Vol 686 ◽  
pp. 388-391 ◽  
Author(s):  
Fei Xue ◽  
Mei Ling Wang ◽  
Qiang Feng

The phase equilibria of Co-base trial alloys of Co-9Al-7.5W, Co-5.5Al-10W and Co-9Al-3W at 1300°C and 900°C were determined in the present investigation. The experimental alloys were γ single-phase alloys at 1300°C, although the existence of the γ' phase and the ε phase was identified due to cooling effect. The nearly cuboidal γ' phase and the plate-like DO19 phase in alloys 9Al-7.5W and 5.5Al-10W were coarsened after long-term annealing at 900°C. It is suggested that the alloy 9Al-7.5W was in γ+γ' two-phase region, while the alloys 5.5Al-10W and 9Al-3W were in γ+DO19 two-phase region and γ singe-phase region at 900°C, respectively.


Author(s):  
Mitsunori Uchida ◽  
Satoshi Someya ◽  
Koji Okamoto ◽  
Hiroyuki Ohshima

When a heat exchanger in a Fast Breeder Reactor cracks, highly pressurized water or steam escapes into the surrounding liquid sodium. A sodium-water reaction then occurs, forming disodium oxide (and hydrogen gas). It can cause secondary damages to the heat exchangers by the reaction heat and erosion corrosion. The released flow of steam from the cracks of the heat exchanger is an underexpanded jet because the ambient pressure outside the tubes is lower than the critical pressure. When the pressure of a jet released at high pressure cannot be reduced to the low pressure of the ambient fluid, the flow is said to be underexpanded. Because this expansion causes a reduction of pressure and the pressure is lower than the critical pressure, the velocity of the flow can reach supersonic speed. Several studies have examined the underexpansion of the gas-gas phase. However, there have been few studies on the underexpansion of gas-liquid two-phase flows. The flow characteristics of the gas-liquid two-phase flow differ from the gas-gas flow because breakups of the bubbles appear in the gas-liquid two-phase flow. Therefore, in this study qualitative measurement was carried out for the purpose of revealing the flow with the underexpanded gas jet injected into water. The gas jet distance L and the expansion angle θ were then obtained from averaged image of a high-speed camera. L and θ increased approximately linearly with increasing pressure. The entrainment velocity and the velocity of entrained water droplets into the gas jet were obtained by PIV. Images of unstable expansion near the jet nozzle were captured for the first time.


Author(s):  
Md. Hamidul Kabir ◽  
Ravshan Makhkamov ◽  
Shaila Kabir

The solution properties and phase behavior of ammonium hexylene octyl succinate (HOS) was investigated in water and water-oil system. The critical micelle concentration (CMC) of HOS is lower than that of anionic surfactants having same carbon number in the lipophilic part. The phase diagrams of a water/ HOS system and water/ HOS/ C10EO8/ dodecane system were also constructed. Above critical micelle concentration, the surfactant forms a normal micellar solution (Wm) at a low surfactant concentration whereas a lamellar liquid crystalline phase (La) dominates over a wide region through the formation of a two-phase region (La+W) in the binary system. The lamellar phase is arranged in the form of a biocompatible vesicle which is very significant for the drug delivery system. The surfactant tends to be hydrophilic when it is mixed with C10EO8 and a middle-phase microemulsion (D) is appeared in the water-surfactant-dodecane system where both the water and oil soluble drug ingredient can be incorporated in the form of a dispersion. Hence, mixing can tune the hydrophile-lipophile properties of the surfactant. Key words: Ammonium hexylene octyl succinate, mixed surfactant, lamellar liquid crystal, middle-phase microemulsion. Dhaka Univ. J. Pharm. Sci. Vol.3(1-2) 2004 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website


2019 ◽  
Vol 3 ◽  
pp. S25
Author(s):  
Benjamin Ehst ◽  
George Han ◽  
Scott Guenthner ◽  
Kimberly Eads ◽  
Abby Jacobson

Abstract not available.


2012 ◽  
Vol 9 (1) ◽  
pp. 131-135
Author(s):  
M.A. Pakhomov

The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.


Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 727
Author(s):  
Shiyun Jin ◽  
Huifang Xu ◽  
Seungyeol Lee

The enigmatic Bøggild intergrowth in iridescent labradorite crystals was revisited in light of recent work on the incommensurately modulated structures in the intermediated plagioclase. Five igneous samples and one metamorphic labradorite sample with various compositions and lamellar thicknesses were studied in this paper. The lamellar textures were characterized with conventional transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The compositions of individual lamellae were analyzed with high-resolution energy-dispersive X-ray spectroscopy (EDS) mapping and atom probe tomography (APT). The average structure states of the studied samples were also compared with single-crystal X-ray diffraction data (SC-XRD). The Na-rich lamellae have a composition of An44–48, and the Ca-rich lamellae range from An56 to An63. Significant differences between the lamellar compositions of different samples were observed. The compositions of the Bøggild intergrowth do not only depend on the bulk compositions, but also on the thermal history of the host rock. The implications on the subsolidus phase relationships of the plagioclase feldspar solid solution are discussed. The results cannot be explained by a regular symmetrical solvus such as the Bøggild gap, but they support an inclined two-phase region that closes at low temperature.


2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 327.1-328
Author(s):  
A. Kavanaugh ◽  
M. H. Buch ◽  
B. Combe ◽  
L. Bessette ◽  
I. H. Song ◽  
...  

Background:The primary treatment goal for patients (pts) with rheumatoid arthritis (RA) is a state of sustained clinical remission (REM) or low disease activity (LDA).1,2Objectives:To assess the long-term sustainability of responses to upadacitinib (UPA), a JAK inhibitor, with or without background csDMARD(s) in pts with RA.Methods:Data are from two phase 3 randomized, controlled trials of UPA in RA pts with roughly similar baseline disease characteristics: SELECT-NEXT enrolled pts with an inadequate response (IR) to csDMARD(s) on background stable csDMARD(s) receiving UPA 15 mg or 30 mg once daily or placebo for 12 weeks (wks); SELECT-MONOTHERAPY enrolled methotrexate (MTX)-IR pts receiving UPA 15 mg or 30 mg monotherapy or blinded MTX for 14 wks. After 12/14 wks, pts could enter a blinded long-term extension and receive UPA 15 mg or 30 mg for up to 5 years. This post hoc analysis evaluated clinical REM (CDAI ≤2.8; SDAI ≤3.3), LDA (CDAI≤10; SDAI≤11), and DAS28(CRP) <2.6/≤3.2 at first occurrence before Wk 84; additionally, these measures were evaluated at 3, 6, and 12 months after the first occurrence for the total number of pts randomized to UPA 15 mg. Sustainability of response was evaluated by Kaplan-Meier only for those pts who achieved REM/LDA and was defined as time to the earliest date of losing response at two consecutive visits or discontinuation of study drug. The predictive ability of time to clinical REM/LDA was assessed using Harrell’s concordance (c)-index (for reference, an index ~ 0.5, indicates no ability to predict; an index of 1 or -1 would be a perfect prediction). The last follow up dates were 22 March, 2018 (SELECT-NEXT) and 25 May, 2019 (SELECT-MONOTHERAPY), when all pts had reached the Wk 84 visit.Results:Through Wk 84, the percent of treated pts achieving CDAI REM/LDA was 43%/79% for those receiving UPA 15 mg with background csDMARD(s) (SELECT-NEXT) and 37%/76% for those receiving UPA 15 mg without background csDMARD(s) (SELECT-MONOTHERAPY). 35%/25% of pts randomized to UPA 15 mg with background csDMARD(s) and 27%/23% of pts randomized to UPA 15 mg without background csDMARD(s) achieved sustained CDAI REM through 6/12 months after the first occurrence. 64%/56% of pts randomized to UPA 15 mg with background csDMARD(s) and 61%/56% of pts randomized to UPA 15 mg without background csDMARD(s) achieved sustained CDAI LDA through 6/12 months after the first occurrence (Figure 1). Time to initial clinical REM/LDA did not appear to be associated with sustained disease control. The c-indices (95%CI) for CDAI REM in the UPA 15 mg with background csDMARD(s) and UPA 15 mg without background csDMARD(s) groups were 0.541 (0.47, 0.62) and 0.568 (0.49, 0.65) and that of LDA were 0.521 (0.46, 0.58) and 0.498 (0.43, 0.56), respectively. Through last follow-up visit, 55% of pts receiving UPA 15 mg with background csDMARD(s) and 62% of pts receiving UPA 15 mg without background csDMARD(s) remained in CDAI REM while 72% and 70% of pts remained in CDAI LDA, respectively (Figure 2). Similar results were observed across other disease activity measures (SDAI REM/LDA and DAS28(CRP) <2.6/≤3.2).Conclusion:More than a quarter and more than a half of pts with RA and prior IR to csDMARD(s) receiving UPA with or without background csDMARD therapy achieved sustained clinical REM and LDA, respectively, across disease activity measures. Sustainability of responses appeared comparable among pts receiving UPA with or without background csDMARDs through up to 84 wks.References:[1]EULAR: Smolen JS, et al. Ann Rheum Dis 2017;76:960–977.[2]ACR: Singh et al. Arthritis & Rheumatology Vol. 68, No. 1, January 2016, pp 1–26.Disclosure of Interests: :Arthur Kavanaugh Grant/research support from: Abbott, Amgen, AstraZeneca, BMS, Celgene Corporation, Centocor-Janssen, Pfizer, Roche, UCB – grant/research support, Maya H Buch Grant/research support from: Pfizer, Roche, and UCB, Consultant of: Pfizer; AbbVie; Eli Lilly; Gilead Sciences, Inc.; Merck-Serono; Sandoz; and Sanofi, Bernard Combe Grant/research support from: Novartis, Pfizer, Roche-Chugai, Consultant of: AbbVie; Gilead Sciences, Inc.; Janssen; Eli Lilly and Company; Pfizer; Roche-Chugai; Sanofi, Speakers bureau: Bristol-Myers Squibb; Gilead Sciences, Inc.; Eli Lilly and Company; Merck Sharp & Dohme; Pfizer; Roche-Chugai; UCB, Louis Bessette Grant/research support from: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, Roche, Sanofi, UCB Pharma, Consultant of: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, Roche, Sanofi, UCB Pharma, Speakers bureau: AbbVie, Amgen, Bristol-Myers Squibb, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, Sanofi, In-Ho Song Shareholder of: AbbVie Inc., Employee of: AbbVie Inc., Yanna Song Shareholder of: AbbVie Inc., Employee of: AbbVie Inc., Jessica Suboticki Shareholder of: AbbVie Inc., Employee of: AbbVie Inc., Peter Nash Grant/research support from: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly and Company, Gilead, Janssen, MSD, Novartis, Pfizer Inc, Roche, Sanofi, UCB, Consultant of: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Gilead, Janssen, MSD, Novartis, Pfizer Inc, Roche, Sanofi, UCB, Speakers bureau: AbbVie, Bristol-Myers Squibb, Celgene, Eli Lilly, Gilead, Janssen, MSD, Novartis, Pfizer Inc, Roche, Sanofi, UCB


Sign in / Sign up

Export Citation Format

Share Document