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Influence of brain death and associated trauma on solid organ histological characteristics

Simas, Rafael; Kogiso, Diogo Haruo; Correia, Cristiano de Jesus; Ferraz da Silva, Luiz Fernando; Silva, Isaac Azevedo; Miranda Costa Cruz, Jose Walber; Sannomiya, Paulina; Pinho Moreira, Luiz Felipe
Fonte: ACTA CIRURGICA BRASILEIRA; SAO PAULO Publicador: ACTA CIRURGICA BRASILEIRA; SAO PAULO
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
15.98%
PURPOSE: To evaluate histopathological alterations triggered by brain death and associated trauma on different solid organs in rats. METHODS: Male Wistar rats (n=37) were anesthetized with isoflurane, intubated and mechanically ventilated. A trepanation was performed and a balloon catheter inserted into intracraninal cavity and rapidly inflated with saline to induce brain death. After induction, rats were monitored for 30, 180, and 360 min for hemodynamic parameters and exsanguinated from abdominal aorta. Heart, lung, liver, and kidney were removed and fixed in paraffin to evaluation of histological alterations (H&E). Sham-operated rats were trepanned only and used as control group. RESULTS: Brain dead rats showed a hemodynamic instability with hypertensive episode in the first minute after the induction followed by hypotension for approximately 1 h. Histological analyses showed that brain death induces vascular congestion in heart (p<0.05), and lung (p<0.05); lung alveolar edema (p=0.001), kidney tubular edema (p<0.05); and leukocyte infiltration in liver (p<0.05). CONCLUSIONS: Brain death induces hemodynamic instability associated with vascular changes in solid organs and compromises most severely the lungs. However, brain death associated trauma triggers important pathophysiological alterations in these organs.; Sao Paulo Research Foundation (FAPESP); Sao Paulo Research Foundation (FAPESP); National Council of Scientific and Technology Development (CNPq); National Council of Scientific and Technology Development (CNPq)

Avaliação hemodinâmica e homogasomêtrica de cadelas submetidas à ovariohisterectomia videolaparoscópica, sob anestesia geral intravenosa contínua com propofol e fentanil, com ou sem o uso de infusão contínua de atracúrio, mediante ventilação controlada com pressão expiratória final positiva ou não.

Muccillo, Marcelo de S.
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
15.98%
A cirurgia laparoscópica requer a criação de um espaço de trabalho intraabdominal, através do pneumoperitônio, e para isto utiliza-se o dióxido de carbono (CO2). As alterações sistêmicas relacionadas ao sistema respiratório ocorrem pelo aumento da pressão intra-abdominal, resultando em diminuição da complacência pulmonar, atelectasia, hipercarbia e hipóxia. A insuflação de CO2 com pressões intraabdominais acima de 8 mmHg produz alterações hemodinâmicas significantes, caracterizadas por decréscimo do débito cardíaco, elevação da pressão arterial. Para que a homeostase hemodinâmica e respiratória seja mantida são necessários protocolos anestésicos adequados e métodos de ventilação mecânica como, por exemplo, a pressão expiratória final positiva final (PEEP). O presente trabalho teve por objetivo avaliar e comparar quatro protocolos anestésicos e ventilatórios distintos em cadelas submetidas à ovariohisterectomia videolaparoscópica eletiva, com uso de pneumoperitônio com CO2 e 12 mmHg de pressão intra-abdominal, sob anestesia geral total intravenosa. Para isso, 16 caninos foram distribuídos em quatro grupos: no grupo 1 (Zeepbloq) os animais receberam atracúrio (0,5 mg.kg-1), propofol (5 mg.kg-1) e fentanil (2 mcg.kg-1)...

Influence of the elevation of the left ventricular diastolic pressure on the values of the first temporal derivative of the ventricular pressure (dP/dt)

Okoshi, Katashi; Fioretto, José Roberto; Bonatto, Rossano César; Tornero, Maria Teresinha Trovarelli; Tucci, Paulo José
Fonte: Sociedade Brasileira de Cardiologia (SBC) Publicador: Sociedade Brasileira de Cardiologia (SBC)
Tipo: Artigo de Revista Científica Formato: 42-46
ENG
Relevância na Pesquisa
15.98%
PURPOSE: To assess the effects of the elevation of the left ventricular end-diastolic pressure (LVEDP) on the value of the 1st temporal derivative of the ventricular pressure (dP/dt). METHODS: Nineteen anesthetized dogs were studied. The dogs were mechanically ventilated and underwent thoracotomy with parasympathetic nervous system block. The LVEDP was controlled with the use of a perfusion circuit connected to the left atrium and adjusted to the height of a reservoir. The elevation of the LVEDP was achieved by a sudden increase in the height of a reservoir filled with blood. Continuous recordings of the electrocardiogram, the aortic and ventricular pressures and the dP/dt were performed. RESULTS: Elevation of the LVEDP did not result in any variation of the heart rate (167±16.0bpm, before the procedure; 167±15.5bpm, after the procedure). All the other variables assessed, including systolic blood pressure (128±18.3mmHg and 150±21.5mmHg), diastolic blood pressure (98±16.9mmHg and 115±19.8mmHg), LVEDP (5.5±2.49 and 9.3±3.60mmHg), and dP/dt (4,855 ± 1,082 mmHg/s and 5,149±1,242mmHg/s) showed significant increases following the expansion of the ventricular cavity. Although the elevation of the dP/dt was statistically significant...

Efeito do bay 41-2272, na pressão arterial de ratos sob tratamento cronico com inibidor da sintese de oxido nitrico

Marcos Zanfolin
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 30/08/2005 PT
Relevância na Pesquisa
15.98%
Recentemente, o composto BAY 41-2272, um derivado da pirazolopiridina, 5-ciclopropil-2-[ 1-(2-fluor-benzil)-IH-pirazol[3, 4-b]piridina-3-il]-pirimidina-4-ilamina, (Bayer AGGermany), foi descrito como ativador específico de GCs de ação NO-independente (STRAUB et. al., 2001; STASCH et. aI., 2001). Experimentos in vitro demonstraram uma potente ativação da GCs pelo BAY 41-2272 nas concentrações de 0.1 nM a 100 J.IM, sendo esta estimulação potencializada na presença de doador de NO (DEA)/NO 1 J.LM (STACH et. al., 2001). Em estudos utilizando enzimas desprovidas de grupamento heme, o BAY 41-2272 não foi capaz de ativá-Ias demonstrando que seu mecanismo, apesar de ser NO-independente, é heme-dependente (STACH e1.al., 2001). Diante do exposto, observa-se que a inibição da síntese de óxido nítrico é responsável, em grande parte, pelo surgimento de processos patológicos, principalmente para o sistema cardiocirculatório. Neste sentido, o presente estudo foi realizado para investigar, principalmente, o efeito de um recente e potente estimulador da GCs (BAY 41-2272, Bayer AG, Germany) - independente de NO na hipertensão e miocardiopatia em ratos, avaliando desta forma a importância dessa via de estimulação na presença da patologia. Foram utilizados no experimento ratos WistarlUni S.P.F....

Deslizamento de fluidos da cavidade orofaringea para traqueia influenciado pela fisioterapia respiratoria em pacientes sob ventilação mecanica

Carla de Oliveira Yokoto
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/02/2004 PT
Relevância na Pesquisa
16.22%
A fisioterapia respiratória pode melhorar a função respiratória, promovendo a oxigenação e a ventilação pulmonar em pacientes acamados, sedados e dependentes de ventilação mecânica. As secreções retidas na face superior do balonete podem estar contaminadas por microorganismos patogênicos e se o material orofaríngeo colonizado chegar aos pulmões, torna-se potencial causador de pneumonia aspirativa. Este trabalho teve como finalidade verificar se as manobras de fisioterapia respiratória podiam influenciar no deslizamento de secreções entre a superfície externa do balonete insuflado do tubo traqueal e a parede da traquéia, indicando a passagem de secreções da cavidade orofaríngea para as vias aéreas inferiores, identificadas através do uso do corante. Foi um estudo experimental prospectivo, utilizando-se o modelo longitudinal. Para tanto, foram estudados 25 pacientes maiores de 18 anos, dependentes de ventilação mecânica, sedados, intubados endotraquealmente por um período de até 120 horas, que podiam permanecer na posição de Fowler 30° e se manter sob ventilação mecânica assistida/controlada, ventilado a volume (8 m1/kg de peso), com pressão expiratória final (PEEP) no valor de 5 a 8 cmH2O e relação inspiração/expiração 1:2. Foram subdivididos em dois grupos: Grupo não experimental (GNE) constituído por pacientes que não receberam atendimento fisioterápico e Grupo experimental (GE)...

Simulação do comportamento térmico de edifícios com fachadas ventiladas

Carvalhal, Catarina Mourão
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
16.31%
Com a entrada em vigor dos novos regulamentos na área de consumo energético de edifícios, torna-se cada vez mais importante a simulação do comportamento térmico destes. Existe ainda a necessidade de criar novas soluções construtivas, sendo uma delas o uso de fachadas ventiladas. As fachadas ventiladas podem ser definidas como um sistema de revestimento exterior de edifícios, cuja principal característica é a existência de uma caixa-de-ar em movimento, resultante do afastamento entre a parede do edifício e o revestimento. O principal objectivo do presente estudo é analisar o sistema construtivo em três regiões climáticas de Portugal: Bragança, Ovar e Évora. Para tal recorreu-se a dois programas de simulação, o EnergyPlus e o DesignBuilder. Com base nos resultados obtidos pelo EnergyPlus calcularam-se os consumos em Aquecimento e Arrefecimento e os respectivos Graus Dias. Observando os resultados, conclui-se que de uma forma geral a utilização de fachadas ventiladas reduz os consumos em Aquecimento e Arrefecimento nas três regiões climáticas. No entanto, é na estação de Arrefecimento que se verifica uma redução mais acentuada. Observou-se ainda que a colocação de um damper nas aberturas melhorava significativamente a prestação do edifício na estação de Arrefecimento. ABSTRACT: With the new regulations in the area of energy consumption of buildings...

Influence of the elevation of the left ventricular diastolic pressure on the values of the first temporal derivative of the ventricular pressure (dP/dt)

Okoshi,Katashi; Fioretto,José Roberto; Bonatto,Rossano César; Tornero,Maria Teresinha Trovarelli; Tucci,Paulo José
Fonte: Sociedade Brasileira de Cardiologia - SBC Publicador: Sociedade Brasileira de Cardiologia - SBC
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/1999 EN
Relevância na Pesquisa
15.98%
PURPOSE: To assess the effects of the elevation of the left ventricular end-diastolic pressure (LVEDP) on the value of the 1st temporal derivative of the ventricular pressure (dP/dt). METHODS: Nineteen anesthetized dogs were studied. The dogs were mechanically ventilated and underwent thoracotomy with parasympathetic nervous system block. The LVEDP was controlled with the use of a perfusion circuit connected to the left atrium and adjusted to the height of a reservoir. The elevation of the LVEDP was achieved by a sudden increase in the height of a reservoir filled with blood. Continuous recordings of the electrocardiogram, the aortic and ventricular pressures and the dP/dt were performed. RESULTS: Elevation of the LVEDP did not result in any variation of the heart rate (167±16.0bpm, before the procedure; 167±15.5bpm, after the procedure). All the other variables assessed, including systolic blood pressure (128±18.3mmHg and 150±21.5mmHg), diastolic blood pressure (98±16.9mmHg and 115±19.8mmHg), LVEDP (5.5±2.49 and 9.3±3.60mmHg), and dP/dt (4,855 ± 1,082 mmHg/s and 5,149±1,242mmHg/s) showed significant increases following the expansion of the ventricular cavity. Although the elevation of the dP/dt was statistically significant...

Gas exchange in abdominal cavity during laparoscopy.

Cameron, A E; Dear, G L; Pocock, T J; Tennant, R W
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1983 EN
Relevância na Pesquisa
26.14%
Gas exchange occurring in the abdominal cavity during laparoscopy, using carbon dioxide as the insufflating gas, was investigated in 25 female patients being ventilated with 66.6% nitrous oxide and 33.3% oxygen. The gas remaining in the abdomen at the end of the procedure was collected and measurements were made using an infrared spectrometer, a paramagnetic analyser and a mass spectrometer. The mean duration of the laparoscopy was 9.5 minutes and the mean volume of carbon dioxide delivered was 6.8 litres. Nitrous oxide concentration in the abdomen was found to increase significantly with the duration of the procedure, varying from 1.4% to 12.8% with a mean of 4.3% (s.d. +/- 2.4). Oxygen concentration measured from 0.1 to 1.8% with a mean of 0.7% (s.d. +/- 0.4). Nitrogen concentration varied from zero to 1.8%, having a mean concentration of 0.8% (s.d. +/- 0.5). Carbon dioxide content was from 85.7 to 99.6% with a mean concentration of 94.2% (s.d. +/- 3.1).

Oral biofilms, periodontitis, and pulmonary infections

Paju, S; Scannapieco, FA
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /11/2007 EN
Relevância na Pesquisa
16.2%
Bacteria from the oral biofilms may be aspirated into the respiratory tract to influence the initiation and progression of systemic infectious conditions such as pneumonia. Oral bacteria, poor oral hygiene, and periodontitis seem to influence the incidence of pulmonary infections, especially nosocomial pneumonia episodes in high-risk subjects. Improved oral hygiene has been shown to reduce the occurrence of nosocomial pneumonia, both in mechanically-ventilated hospital patients and non-ventilated nursing home residents. It appears that oral colonization by potential respiratory pathogens, possibly fostered by periodontitis, and possibly by bacteria specific to the oral cavity or to periodontal diseases contribute to pulmonary infections. Thus, oral hygiene will assume an even more important role in the care of high-risk subjects – patients in the hospital intensive care and the elderly. The present paper critically reviews the recent literature on the effect of oral biofilms and periodontitis on pneumonia.

Genetic relationships between Candida albicans strains isolated from dental plaque, trachea, and bronchoalveolar lavage fluid from mechanically ventilated intensive care unit patients

Heo, Seok-Mo; Sung, Robert S.; Scannapieco, Frank A.; Haase, Elaine M.
Fonte: CoAction Publishing Publicador: CoAction Publishing
Tipo: Artigo de Revista Científica
Publicado em 20/06/2011 EN
Relevância na Pesquisa
26.35%
Candida albicans often resides in the oral cavity of healthy humans as a harmless commensal organism. This opportunistic fungus can cause significant disease in critically ill patients, such as those undergoing mechanical ventilation in the intensive care unit (ICU) having compromised local airway defense mechanisms. The goal of this study was to determine the intra- and inter-patient genetic relationship between strains of C. albicans recovered from dental plaque, tracheal secretions, and the lower airway by bronchoalveolar lavage of patients undergoing mechanical ventilation. Three pulsed-field gel electrophoresis (PFGE) typing methods were used to determine the genetic relatedness of the C. albicans strains, including electrophoretic karyotyping (EK) and restriction endonuclease analysis of the genome using SfiI (REAG-S) and BssHII (REAG-B). The C. albicans isolates from dental plaque and tracheo-bronchial sites from the same patient were genetically indistinguishable and retained over time, whereas strains from different patients usually separated into different genotypes. Among the three methods, REAG-B proved to be the most discriminatory method to differentiate isolates. The finding of genetically similar strains from the oral and tracheo-bronchial sites from the same patient supports the notion that the oral cavity may serve as an important source for C. albicans spread to the trachea and lung of mechanically ventilated patients.

Long-term survival of salivary streptococci on dental devices made of ethylene vinyl acetate

Ogawa, Taiji; Yamasaki, Sayaka; Honda, Mariko; Terao, Yutaka; Kawabata, Shigetada; Maeda, Yoshinobu
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.2%
Bacterial infection associated with the use of medical or dental devices is a serious concern. Although devices made of ethylene vinyl acetate (EVA) are often used in the oral cavity, there are no established standards for their storage. We investigated bacterial survival on EVA sheets under various storage conditions to establish a standard for hygienic storage of such dental devices. Bacterial counts were evaluated, which showed a significant decrease after washing with sterilized water, mechanical brushing and rinsing, and using Mouthguard Cleaner as compared to untreated samples. In addition, no bacteria were detected on samples stored 2 days or longer in a ventilated environment, whereas they were detected for up to 14 days on samples without any cleaning stored in a closed environment. Bacterial counts for the untreated samples gradually declined, while surviving bacteria on samples treated with sterilized water and mechanical brushing showed a rapid decrease. Additionally, bacterial identification using polymerase chain reaction (PCR) revealed that Streptococcus oralis was dominantly detected on salivary samples after 14 days of storage among both two subjects. For effective hygienic storage of dental devices made of EVA, washing with sterilized water is important to remove absorbed salivary compounds along with storage in a ventilated environment.

A new nasal cavity nursing methods application in patients with mechanical ventilation

Wei, Liuqing; Qin, Gang; Yang, Xining; Hu, Meichun; Jiang, Fufu; Lai, Tianwei
Fonte: Professional Medical Publicaitons Publicador: Professional Medical Publicaitons
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
26.14%
Objective: To compare different nasal cavity nursing methods on mechanically ventilated patients.

Frequency and Intensive Care Related Risk Factors of Pneumothorax in Ventilated Neonates

Bhat Yellanthoor, Ramesh; Ramdas, Vidya
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.31%
Objectives. Relationships of mechanical ventilation to pneumothorax in neonates and care procedures in particular are rarely studied. We aimed to evaluate the relationship of selected ventilator variables and risk events to pneumothorax. Methods. Pneumothorax was defined as accumulation of air in pleural cavity as confirmed by chest radiograph. Relationship of ventilator mode, selected settings, and risk procedures prior to detection of pneumothorax was studied using matched controls. Results. Of 540 neonates receiving mechanical ventilation, 10 (1.85%) were found to have pneumothorax. Respiratory distress syndrome, meconium aspiration syndrome, and pneumonia were the underlying lung pathology. Pneumothorax mostly (80%) occurred within 48 hours of life. Among ventilated neonates, significantly higher percentage with pneumothorax received mandatory ventilation than controls (70% versus 20%; P < 0.01). Peak inspiratory pressure >20 cm H2O and overventilation were not significantly associated with pneumothorax. More cases than controls underwent care procedures in the preceding 3 hours of pneumothorax event. Mean airway pressure change (P = 0.052) and endotracheal suctioning (P = 0.05) were not significantly associated with pneumothorax. Reintubation (P = 0.003)...

Experimental investigation of ventilated cavities.

Kinnear, Richard James
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado
EN_US
Relevância na Pesquisa
26.35%
A wedge with a 3.5 inch chord and a half-angle of 4.1 degrees is tested in the MIT Propeller Tunnel. No pulsations were observed on the cavity. Thus, the attempt to verify the theory that pulsations are possible in an infinite medium (without a free surface) is inconclusive. Although there exist a variance in the cavitation number between theory and experiment, the data plotted show that the general shape of the curve for a 4.1 degree wedge is correct. The primary discrepancy is in the pressure recording methods. Visual observations become difficult when ventilated cavities are generated in the test section. It takes only about 5 to 10 seconds for the air introduced into the cavity to recirculate through the tunnel.

Time Resolved Two Dimensional X-Ray Densitometry of a Two Phase Flow Downstream of a Ventilated Cavity

MAKIHARJU, Simo A; GABILLET, Céline; PAIK, Bu-Geun; CHANG, Natasha A; PERLIN, Marc; CECCIO, Steven L
Fonte: Arts et Métiers ParisTech Publicador: Arts et Métiers ParisTech
EN
Relevância na Pesquisa
56.55%
To measure the void fraction distribution in gas-liquid flows, a two-dimensional x-ray densitometry system was developed. This system is capable of acquiring a two-dimensional projection with a 225 cm2 area of measurement through 21 cm of water. The images can be acquired at rates on the order of 1 kHz. Common sources of error in x-ray imaging, such as x-ray scatter, image distortion, veiling glare, and beam hardening were considered, and mitigated. The measured average void fraction was compared success fully to that of a phantom target and found to be within 1%. To evaluate the performance of the new system, the flow in and downstream of a ventilated nominally two-dimensional partial cavity was investigated and compared to measurements from dual tip fiber optical probes and high speed video. The measurements were found to have satisfactory agreement for void fractions above 5% of the selected void fraction measurement range.; Office of Naval Research under grant N00014-10-1-0974

Thermal and structural performances of insulated cavity rammed earth wall houses.

Dong, Xiang
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2015
Relevância na Pesquisa
36.22%
Rammed earth (RE) wall construction is perceived to carry extremely low embodied energy and have desirable thermal performance without much energy input for heating and cooling due to the thermal mass effect. In Australia, however, because of the low thermal resistance (R-value) of RE material, it is very difficult for houses constructed with only solid RE walls to comply with the Deemed-to-Satisfy Provision provided in the National Construction Code (NCC) by the Building Code of Australia, which specifies the minimum R-value for external walls. The NCC provides an alternative provision, named the Energy Efficiency Provision, which states a maximum allowance of energy use by a residential house. As houses have the potential to consume little energy load particularly when passive design strategies are implemented, houses built with RE walls may still be able to comply with the Energy Efficiency Provision of the NCC. Adding thermal insulation to the wall construction is one way to ensure that RE wall houses comply with NCC. Normally, rigid board foam insulation can be inserted in the middle of RE walls to maintain the aesthetics of the wall surfaces and part of the thermal mass effect. The result of this solution is an insulated cavity rammed earth (ICRE) wall system. This solution...

A performance-prediction theory for partially submerged ventilated propellers

Furuya, Okitsugu
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em /02/1985
Relevância na Pesquisa
26.2%
A partially submerged propeller theory was developed by employing a singularity distribution method. Unsteady pressure doublets and pressure sources represented the blade camber and blade-and-cavity thickness respectively. The induced velocities were derived by reducing the formula to a lifting-line configuration. The free-surface effect was considered by use of the image method. The induced velocities contained the singular integrals of 5th order, which are usually numerical unstable. An effort was made to derive numerically stable formulae from these singular equations by applying a method similar to the induction-factor method of Morgan & Wrench (1965) and Lerbs (1952) used for steady-state fully wetted propeller problems. These new formulae are not only applicable to the present partially submerged ventilated propeller problem, but also to general unsteady subcavitating and cavitating propeller problems such as propeller starting-up and non-periodic loading problems. By combining the two-dimensional water entry-and-exit theory of Wang (1979), the thrust and torque coefficients were calculated for representative partially submerged propellers and favourably compared with the experimental data.

A Preliminary Study of the Effect of the Free Surface on a Three-dimensional Cavity Produced by a Circular Disk

Bate, E. R., Jr.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em /03/1964
Relevância na Pesquisa
36.3%
The influence of the free surface on the cavitation associated with bodies operating at shallow submergences has long been of interest because of the practical use for such information. The performance of hydrofoil boats is very much dependent on the submergence below the water surface of the hydrofoils, for example. Because of the extreme complexity introduced by the consideration of boundaries of any sort, most theories relating the parameters associated with cavitation are developed for a fluid of "infinite" extent. The task of determining the effects of the boundaries for such a cavitating flow problem then becomes one of experimentation. Such an experiment was performed to determine the free surface effects on a supercavitating, flat plate hydrofoil in two-dimensional flow p:: However, most real flow situations are three dimensional, and the present experiment is a preliminary study to determine the effects of the free surface on the geometry of a ventilated cavity in such a flow. Specifically, the variation of the length of a cavity due to submergence is studied. The cavity is produced by a sharp- edged, circular disk normal to the flow. Figures la and lb show this cavity at two different ventilation numbers. This experiment was planned as a preliminary study to determine the general trend and order of magnitude of the free surface effects...

Free-surface water tunnel studies of a family of base-ventilated hydrofoils

Brentjes, J.
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em /06/1962
Relevância na Pesquisa
26.31%
This test program is one of a series designed to investigate the properties of base-ventilated hydrofoils. The purpose of this study was to determine the two-dimensional force and ventilation characteristics of an uncambered hydrofoil which could be truncated by removing four removable trailing edge sections. The program was performed at the request of T. G. Lang of the Naval Ordnance Test Station, Pasadena, who in Reference 1 analyzed the possibilities of reducing the cavity drag of base-ventilated hydrofoils by selecting appropriate section profiles and foil base thicknesses. Using a profile developed in Reference 1, it was intended to study the effects of ventilation air flow rate, angle of attack, and the position of the trailing edge cutoff points, and to compare the experimental values of the drag with those predicted from a linearized flow theory.

Indoor air quality analysis based on the ventilation effectiveness for CO2 contaminant removal in ventilated cavities

Serrano-Arellano,J.; Gijón-Rivera,M.; Riesco-Ávila,J.M.; Xamán,J.; Álvarez,G.
Fonte: Sociedad Mexicana de Física Publicador: Sociedad Mexicana de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2014 EN
Relevância na Pesquisa
36.44%
A theoretical study to determine an optimal configuration for removal a CO2 contaminant from inside a room is presented. The geometry considered was a 2D ventilated cavity in turbulent flow regime and solving the governing equations of mass, momentum and chemical species by the finite volume method. The interval of Reynolds number under study was 0 ≤ Re ≤ 2.5 X 10(4). The air inlet gap is located on the lower side of vertical right wall of the cavity. Three configurations of the cavity varying the air outlet gap on vertical left wall were analysed: in the upper side (case A), in the middle side (case B), and in the lower side (case C). From the results, case A removed the most amount of contaminant from inside room for a Re = 5 x 10³, which had an effect on energy savings. The lower levels of contaminant for higher Reynolds numbers were obtained for the case B. The case C was the less desirable for contaminant removal purposes.