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Buoyant jet and two-phase jet-plume modeling for application to large water pools
Norman, Timothy L.,Revankar, Shripad T. Elsevier 2011 Nuclear engineering and design Vol.241 No.5
<P><B>Highlights</B></P><P>► A two-phase jet-plume model was developed to predict pool thermal response, pool surface temperature and consequently the pool cover gas pressure in enclosed spaces such as nuclear reactor wetwell. ► The jet-plume half-width, centerline velocity and temperature along the axis defining the plume's trajectory were solved as variables along the path. ► The pool surface temperature prediction is comparable to experimental data within 0.5°C.</P> <P><B>Abstract</B></P><P>Models of a single-phase liquid-into-liquid buoyant jet and a two-phase vapor-into-liquid turbulent jet-plume injected in horizontal orientation were developed for analyzing the dynamics of the mixing characteristics and thermal response for shallow submergence of the source in large pools. These models were developed from the Reynolds averaged Navier–Stokes equations in the cylindrical system for steady axisymmetric flow and incorporated the integral plume theory. The bases for the general assumptions such as self-similarity and use of Gaussian profiles to represent the velocity field across the effluent cross-section are examined. Subroutines were developed to reproduce the governing differential equations formulated from the continuity, momentum and conservation of buoyancy or energy equations which treats the jet-plume's half-width, velocity and temperature as variables and seek solutions of these variables along the jet-plume trajectory. Information on empirical closure relations obtained from experimental data such as the coefficient-of-entrainment, bubble slip velocity, momentum amplification factor, and plume spread-ratios for buoyancy and density-defect which are available for adiabatic cases were applied to the case of steam-into-water. Solutions were obtained without cross-flow in a linearly stratified ambient and then with cross-flow in a homogeneously mixed ambient for the single-phase formulation that represents a complete condensation scenario of a buoyant jet. The model was finally extended to the turbulent two-phase jet-plume case and the results were compared to available jet-plume pool condensation data. The analysis and results proved to be comparable to experimental data in predicting the pool surface temperature to within 0.5°C, however, temperature fluctuations along the jet-plume path were not adequately captured by the model since an oscillating input component was not incorporated in the model formulation; indeed the pool surface temperature proved to be of higher importance, which was adequately captured by the model.</P>
Chaitanya Baban Chikhale,Ketan Shripad Khurjekar,Ashok Kumar Shyam,Parag Kantilal Sancheti 대한척추외과학회 2017 Asian Spine Journal Vol.11 No.2
Study Design: This was a single surgeon, single center-based retrospective study with prospective data collection. Purpose: To assess the correlation between T2-weighted magnetic resonance imaging (MRI) signal intensity (SI) changes and factors such as age, duration of symptoms, baseline modified Japanese Orthopedic Association (mJOA) score and to determine its prognostic value in predicting recovery after surgery. Overview of Literature: Whether intramedullary cord T2-weighted MRI SI changes can predict operative outcomes of cervical myeloradiculopathy remains debatable, with only a few prospective studies analyzing the same. Methods: Forty-six consecutive patients who underwent cervical myeloradiculopathy were included and were followed up for an average of 1 year. Preoperative T2-weighted MRI SI grading was performed for all patients. The correlation between MRI SI changes and age, duration of symptoms, preoperative mJOA score, and mJOA score at 1-year follow-up were analyzed. Results: Fifteen patients had single-level (21.73%) or double-level (10.86%) prolapsed discs; 54.34% had degenerative cervical spondylosis with canal stenosis or multilevel disc prolapse and 13.07% had ossified posterior longitudinal ligaments. The mean age was 56.17±9.53 years (range, 35–81 years). The mean baseline mJOA score was 10.83±2.58 (range, 6–16), which postoperatively improved to 13.59±2.28 (range, 8–17; p <0.001). There was a statistically significant correlation between mJOA score at 1 year and MRI T2 SI grading (p =0.017). Conclusions: Patients with longer symptom durations had high grades of intramedullary cord T2-weighted MRI SI changes. Age and preoperative neurological status were not significantly correlated with the existence of intramedullary cord SI changes. However, patients without or with mild and diffuse intramedullary cord T2-weighted MRI SI changes had better postoperative neurological recovery than those with sharp and focal SI changes.
Qu, Xiaohang,Revankar, Shripad T.,Tian, Maocheng Elsevier 2017 Nuclear engineering and design Vol.320 No.-
<P><B>Abstract</B></P> <P>Bubble formation and condensation of steam-air mixture vertically injected in a subcooled water pool was simulated, combining thermal phase change model into the two continuous phase free surface model of ANSYS CFX 17.1. Continuous surface force model was used to calculate surface tension force and the influence of non-condensable gas was accounted for by component transportation equation and assumption of interface temperature equal to saturation temperature at local partial steam pressure. The thermal phase change model includes an experimental correlation for liquid side sensible heat transfer. Based on available experiment data from literatures, singular pure steam bubble and steam-mixture bubble in a pool were first simulated to see the predictability of the proposed method and then, the same method was applied to the bubble formation, detachment and condensation process of injected steam air mixture from a nozzle. Bubble dimeter, water subcooling and non-condensable gas concentration studied range from 4.9mm to 50mm, 12K to 40K, and 0 to 31.5% respectively. The results of the computations indicate that the present method can predict very well the bubble formation and condensation both for pure steam case and with non-condensable gas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bubble formation and condensation process injected from a nozzle is studied numerically. </LI> <LI> Euler-Euler two-fluid free surface model and species model from are coupled together. </LI> <LI> Influence of non-condensable gas is considered. </LI> <LI> Bubble shape variation histories are shown in comparison with experiments. </LI> </UL> </P>
B. T. S. Ramanujam,S. Radhakrishnan,Shripad D. Deshpande 한국고분자학회 2017 Macromolecular Research Vol.25 No.4
Polyethersulfone (PES)-7 wt% graphite- x wt% filler (carbon black (CB), carbon nanofiber (CNF), expanded graphite (ExGr)) hybrid composites are synthesized by solution blending route. The electrical percolation threshold in hybrid composites varies exponentially with the aspect ratio of the second conducting filler. The aspect ratio of the second conducting filler has been found to vary in the order CB < CNF < ExGr. The percolation threshold is identified at 0.05 wt%, 0.4 wt%, 1.3 wt% for ExGr, CNF and CB added PES-7 wt% graphite composites. Through plane thermal conductivity of PES-x wt% graphite-y wt% CB (x=10, 20, 30, 40, 50, 60, y=0, 3, 7) hybrid composites has been found to increase with the addition of CB. Thermal conductivity has been increased to 0.42 W/m-K when 7 wt% CB is added to PES-60 wt% graphite from 0.2 W/m-K. Reduction of interparticular distance with the increased loading of CB facilitates better thermal transport. Aspect ratios of second conducting fillers have been found out from transmission electron microscopy and scanning electron microscopy analysis.
ECONOMIC VIABILITY TO BeO-UO_2 FUEL BURNUP EXTENSION
S. K. KIM,W. I. KO,H. D. KIM,정양헌,방성식,SHRIPAD T. REVANKAR 한국원자력학회 2011 Nuclear Engineering and Technology Vol.43 No.2
This paper presents the quantitative analysis results of research on the burnup effect on the nuclear fuel cycle cost ofBeO-UO_2 fuel. As a result of this analysis, if the burnup is 60 MWD/kg, which is the limit under South Korean regulations,the nuclear fuel cycle cost is 4.47 mills/kWh at 4.8wt% of Be content for the BeO-UO_2 fuel. It is, however, reduced to 3.70mills/kWh at 5.4wt% of Be content if the burnup is 75MWD/kg. Therefore, it seems very advantageous, in terms of theeconomic aspect, to develop BeO-UO_2 fuel, which does not have any technical problem with its safety and is a high burnup& long life cycle nuclear fuel.
Qiu, Binbin,Yang, Qingchuan,Yan, Junjie,li, Gen,Revankar, Shripad T. Elsevier 2017 Experimental thermal and fluid science Vol.88 No.-
<P><B>Abstract</B></P> <P>The propagation characteristics of pressure oscillation in direct contact condensation with low mass flux steam jet have been investigated experimentally. Steam is injected into subcooled water at one atmosphere pressure with steam mass flux and water temperature range of 186–272kg/(m<SUP>2</SUP> s) and 293–343K. The pressure oscillation propagates in the form of wave with stable dominant frequency, however the wave intensity attenuates with the increasing distance from the oscillation source. The root mean square of pressure wave <I>p</I> <SUB>rms</SUB> attenuates rapidly with the increasing dimensionless radial distance from the nozzle exit. At about dimensionless radial distance <I>R</I> =100, the <I>p</I> <SUB>rms</SUB> is attenuated by about 90%. Although the dominant frequency of the pressure oscillation is constant during the propagation, after <I>R</I> =100, there will be not enough energy for the pressure oscillation to resonate with relevant equipment. A correlation equation to calculate the root mean square of pressure oscillation along the radial distance is given. The prediction errors are within ±30% compared with the experimental data.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The pressure oscillation propagates in the form of wave. </LI> <LI> In the propagation process, the frequency remains the same but the intensity attenuates. </LI> <LI> A correlation to calculate the <I>p</I> <SUB>rms</SUB> along the radial distance is given. </LI> <LI> At about R=100, the <I>p</I> <SUB>rms</SUB> is attenuated by about 90% and most of the energy is dissipated. </LI> </UL> </P>
Shailesh Ramakant Hadgaonkar,Ashok Kumar Shyam,Kunal Chandrakant Shah,Ketan Shripad Khurjekar,Parag Kantilal Sancheti 대한척추외과학회 2014 Asian Spine Journal Vol.8 No.5
Osteoblastomas are bone forming lesions arising mainly from posterior elements of the vertebra. They are commonly encountered in the cervical and lumbar regions. We present a case of a thoracic osteoblastoma which is extra osseous and is not communicating with any part of the vertebra present intraforaminally. This is a rare presentation of an osteoblastoma. Imaging studies do not accurately diagnose the osteiod lesion. The size of the lesion and cortical erosion seen on the computed tomography scan help in differentiating the osteoid osteoma and osteoblastoma, but they are less sensitive and specific. Thus a histopathology is the investigation of choice to diagnose the osteoblastoma. Early and adequate removal of mass prevents malignant transformation, metastasis, and recurrence. In our case we excised the pars interarticularis unilaterally, removed the osteoid mass intact, and performed unilateral instrumented fusion. There was no recurrence and solid fusion was seen at 3 years follow up.
Kumaran, Aswathy,Guruvare, Shyamala,Sharan, Krishna,Rai, Lavanya,Hebbar, Shripad Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.11
Purpose: To assess chemoradiation related acute morbidity in women with carcinoma cervix and to find and correlation between hematologic toxicity and organ system specific damage. Materials and Methods: A prospective study was carried out between August 2012 and July 2013 enrolling 79 women with cancer cervix receiving chemo-radiotherapy. Weekly assessment of acute morbidity was done using the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 4 and the toxicities were graded. Results: Anemia [77 (97.5%)], vomiting [75 (94.8%)] and diarrhea [72 (91.1%)], leukopenia [11 (13.9%)], cystitis [28 (35.4%], dermatitis [19 (24.1%)] and fatigue [29 (36.71%)] were the acute toxicities noted. The toxicities were most severe in $3^{rd}$ and $5^{th}$ week. All women could complete radiotherapy except two due to causes unrelated to radiation morbidity; seven (8.86%) had to discontinue chemotherapy due to leukopenia and intractable diarrhea. Though there was no correlation between anemia and other toxicities, it was found that all with leukopenia had diarrhea. Conclusions: Chemoradiation for cancer cervix is on the whole well tolerated. Leukopenia and severe diarrhea were the acute toxicities that compelled discontinuation of chemotherapy in two women. Though anemia had no correlation with gastrointestinal toxicity, all of those with leukopenia had diarrhea.
Awate, Shobhana Vaman,Waghmode, Suresh Babasaheb,Kashinath Rangu,Patil, Agashe, Mangala Shripad,Joshi, Praphulla Narahar 한국화학공학회 2001 Korean Journal of Chemical Engineering Vol.18 No.2
Ultrasonication method was employed for preparation of zirconia-pillared montmorillonite (Zr-PILC) by using polyhydroxy zirconium cation. The influences of various preparation parameters such as pH, concentration of pillaring agent, aging period on physico-chemical properties of Zr-PILCs are reported. The characterization was done by using different characterizing tools such as powder X-ray diffraction (XRD), thermal analysis (TG/DTA), Fourier transform infrared spectroscopy (FITR), X-ray photo-electron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF) and surface area measurements. Effective pillaring was obtained in the pH range 2.0-2.8 at reduced preparation time by using ultrasonication. Ultrasonication, especially at higher pH and concentration of pillaring agent with no aging after ultrasonic agitation of the clay slurry was found to increase zirconium content and specific BET surface area leaving no scope for remarkable increase in d001 spacing. The presence of -OH groups attached to Zr has been revealed by pyridine-adsorbed FTIR, TG/DTA and XPS techniques. The acidic character, ease of accessibility and good dispersion of active sites in Zr-PILC were found to be controlling factors for the challenging activity in hydroxylation reaction of phenol. Probably, this first report on the use of Zr-PILC in hydroxylation of phenol and its preparation by employing ultrasonication technique may attract great attention in the catalysis area of academic and industrial importance.