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The accuracy of non-invasive blood pressure monitoring when compared to intra-arterial blood pressure monitoring in patients with severe pre-eclampsia during an acute hypertensive crisisDalla, Sangita 12 1900 (has links)
Thesis (MMed (Obstetrics and Gynaecology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: OBJECTIVE: The aim of this study was to compare the accuracy of non-invasive blood pressure measurements, using automated and manual devices, against invasive intra-arterial blood pressure measurements in patients with pre-eclampsia, during a hypertensive blood pressure peak.
STUDY DESIGN: In this prospective study, women admitted to the Obstetrics Critical Care Unit, with confirmed pre-eclampsia and acute severe hypertension, who had an intra-arterial line in situ, were asked to participate. During an intra-arterial blood pressure peak, both an automated oscillometric and a blinded manual aneroid sphygmomanometric blood pressure was recorded. These two methods of blood pressure measurements were compared to intra-arterial blood pressure measurements. The accuracy of a mean arterial pressure (MAP) ≥ 125mmHg in detecting a systolic blood pressure (SBP) ≥ 160mmHg, using all three methods, was also determined.
RESULTS: There was poor correlation between intra-arterial SBP and automated and manual SBP (r = 0.34, p < 0.01; r = 0.41, p < 0.01 respectively). The mean differences between automated and manual SBP compared to the intra-arterial SBP was 24 ± 17mmHg (p < 0.01) and 20 ± 15 mmHg (p < 0.01) respectively. There was better correlation between intra-arterial diastolic blood pressure (DBP) and automated and manual DBP (r = 0.61, p < 0.01; r = 0.59, p < 0.01 respectively). The mean differences of the automated and manual DBP was not statistically significant when compared to the intra-arterial DBP. There was poor correlation between the intra-arterial MAP and the automated MAP (r = 0.44, p < 0.01) and good correlation with the manual MAP (r = 0.56, p < 0.01). The mean differences of the automated and manual MAP were statistically significant (5 ± 13mmHg, p < 0.01; 8 ± 11mmHg, p < 0.01 respectively). The sensitivity of automated and manual methods in detecting a SBP ≥ 160mmHg was 23.4% and 37.5% respectively. A MAP ≥ 125mmHg in detecting a SBP ≥ 160mmHg, when using intra-arterial, automated and manual methods of blood pressure measurements showed low sensitivity (35.9%, 21.9% and 17.2% respectively).
CONCLUSION: This study demonstrated that both the automated and manual methods of blood pressure measurements were not an accurate measure of the true systolic intra-arterial blood pressure, when managing pre-eclamptic patients with acute severe hypertension. In such situations, intra-arterial blood pressure monitoring should be used when possible. When this is not possible, manual aneroid sphygmomanometry is recommended. Underestimating blood pressure, particularly SBP, may lead to severe maternal morbidity and mortality. / AFRIKAANSE OPSOMMING: DOELWIT: Die doel van hierdie studie is om die akuraatheid van nie invasiewe bloeddruk metings, wanneer geneem met outomatiese en manuele aparate, te vergelyk met intra-arteriele bloed druk metings in pasiente met pre-eklampsie, gedurende ‘n hipertensiewe bloeddruk piek.
STUDIE ONTWERP: In hierdie prospektiewe beskrywende dwarssnit studie, was pasiente wat toegelaat was tot die Obstetriese Kritieke Sorg Eenheid met pre-eklampsie, akute erge hipertensie en ‘n intra-arteriele lyn in situ gevra om deel te neem. Gedurende ‘n intra-arteriele erge hipertensiewe piek is beide die outomatiese ossilometriese en die geblinde aneroide sfigmometer lesing neergeskryf. Hierdie twee metodes van non invasiewe bloed druk lesings is vergelyk met intra-arteriele bloed druk lesings. Die akuraatheid van ‘n gemiddelde arteriele bloeddruk ≥ 125mmHg om ‘n sistoliese bloeddruk ≥ 160mmHg op te tel met gebruik van al die drie metodes is ook uitgewerk.
RESULTATE: Daar was swak korrelasie tussen intra-arteriele sistoliese bloed druk (SBD) metings en outomatiese en manuele SBD (r = 0.34, p < 0.01; r = 0.41, p < 0.01 onderskeidelik). Die gemiddelde verskille tussen outomatiese en manuele SBD wanneer vergelyk met intra-arteriele SBD was 24 ± 17mmHg (p < 0.01) en 20 ± 15 mmHg (p < 0.01) onderskeidelik. Beter korrelasie was gevind tussen intra-arteriele diastoliese bloed druk (DBD) en outomatiese en manuele DBD (r = 0.61, p < 0.01; r = 0.59, p < 0.01 onderskeidelik). Die gemiddelde verskille tussen outomatiese en manuele DBD wanneer dit vergelyk was met intra-arteriele DBD was nie statisties betekenisvol nie. Daar was swak korrelasie tussen intra arteriele gemiddelde arteriele bloeddruk en outomatiese gemiddelde arteriele bloeddruk (r = 0.44, p < 0.01) en beter korrelasie met manuele gemiddelde arteriele bloeddruk (r = 0.56, p < 0.01). Die gemiddelde verskille van outomatiese en manuele gemiddelde arteriele bloeddruk was betekenisvol (5 ± 13mmHg, p < 0.01; 8 ± 11mmHg, p < 0.01 onderskeidelik). Die sensitiwiteit van outomatiese en manuele metodes om ‘n intra-arteriele SBD ≥ 160mmHg op te tel was 23.4% en 37.5% onderskeidelik. Die vermoë van ‘n gemiddelde arteriele bloeddruk ≥ 125mmHg om ‘n SBD ≥ 160mmHg op te tel, gemeet deur intra-arterieel, outomatiese en manuele metodes het lae sensitiwiteit getoon (35.9%, 21.9% en 17.2% onderskeidelik).
GEVOLGTREKKING: Hierdie studie het gedemonstreer dat outomatiese en manuele metodes van bloeddruk meting nie akurate metodes is om ware intra-arteriele sistoliese bloeddruk te meet in pasiente met erge pre-eklampsie tydens ‘n erge hipertensiewe episode nie. In hierdie omstandighede moet intra-arteriele bloeddruk gemeet word indien beskikbaar. Indien dit nie beskikbaar is nie moet die manuele aneroiede sfigmomanometer gebruik word. Onderskatting van bloeddruk, veral sistoliese bloeddruk, kan lei tot erge moederlike morbiditeit en mortaliteit.
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Développement d’une nouvelle méthode de mesure du rythme cardiaque et du débit sanguin fondée sur les perturbations localisées d’un champ magnétique / Novel method of blood pulse and flow measurement using the disturbance created by blood flowing through a localized magnetic fieldPhua, Chee Teck 21 September 2012 (has links)
La mesure et le contrôle du pouls et du flux sanguin en continu sont d'importants paramètres pour l'évaluation de signes essentiels physiologiques sur la condition de santé d'un individu. Les dispositifs commerciaux existants, ainsi que les méthodes de recherche ou utilisées dans le milieu médical exigent un bon contact électrique ou optique pour obtenir cette mesure en continu. Pendant ces travaux de recherche, une méthode originale non invasive de mesure du rythme cardiaque fondée sur la perturbation localisée d'un champ magnétique au passage du flux sanguin a été développée, permettant l'acquisition des signaux à travers les vêtements, la transpiration, les salissures ou autres polluants dans l'environnement proche du capteur. Cette méthode est appelée la Signature Sanguine par Modulation Magnétique (MMSB) et les mesures ont été accomplies sur de multiples individus. Le système a été modélisé mathématiquement et simulé dans un environnement multiphysique, puis validé par l'utilisation des données expérimentales. Les résultats de mesure, en utilisant la méthode MMSB, pour le pouls et le flux sanguin ont été comparés et se trouvent bien corrélés, avec les résultats obtenus grâce à d'autres instruments. De plus, deux dispositifs ont été développés et sont en cours de commercialisation, pour des applications de vie quotidienne / Continuous pulse rate, blood pressure and blood flow monitoring are important for the assessment of physiological vital signs as these are able to provide continuous feedback on the health condition of an individual. Existing commercial, medical and research methods to continuously acquire such these physiological vital signs require good electrical or optical contact. During this research, a magnetic based sensing method, at room temperature, for blood pulse, flow and pressure is developed to achieve data acquisition through fabric, environmental contaminants and body-fluids. This method is named Modulated Magnetic Signature of Blood (MMSB) and physical measurements were conducted on multiple subjects, mathematically modelled and simulated in a multi-physics environment with verification through use of measurement data. Measurement results, using MMSB, for blood pressure and blood flow were compared, and found to be well correlated, with lifestyle device and medical research instruments respectively. In addition, two devices are developed, and are in the midst of commercialization, to support lifestyle applications
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A model-based study on the effects of aortic blood pressure on the heart sounds and its applications. / CUHK electronic theses & dissertations collectionJanuary 2006 (has links)
2. A modified model of heart-arterial system was proposed for describing the timing of the second heart sound as a result of the heart-arterial interaction. Simulation results suggest that RS2 bears a significant negative correlation with both SBP and DBP as heart rate, cardiac contractility and peripheral resistance varies. The hypothesis was supported by the experimental data. To our knowledge, it is the first study describing the relation of the timing of S2 to BP by both the model-based study and experimental data. / 3. As a preliminary study, a linear predication model using RS2 with a novel calibration scheme was proposed for BP estimation and it has been evaluated in clinical test on 85 volunteers including 18 hypertensives. The results indicate that the approach has the potential to achieve the accuracy required for medical diagnosis. / Cuffless BP measurement has been proposed as a new concept in recent years to realize the continuous monitoring of BP. This research focuses on the investigation of cuffless BP monitoring technique using heart sound information. Specifically, the thesis proposes a new cuffless technique based on the timing of the second heart sound (S2), which will enable a novel wearable design of BP monitor, for instance, a multifunctional electronic stethoscope. / Finally, based on the findings on both theoretical and experimental studies, a linear prediction model with a novel calibration scheme has been proposed to estimate the BP using 1/RS2. The proposed method was evaluated in a clinical test on 85 volunteers aged 40+/-13 years, including 18 hypertensives. The average of BP measured by simultaneous ausculatory and oscillometric approaches was used as a reference. The results of clinical test shows that the RS2 based approach can estimate SBP and DBP within the 2.1+/-7.4 mmHg and 0.8+/-6.6 mmHg of the reference respectively, indicating the approach has the potential to achieve the accuracy required for medical diagnosis according to AAMI standard (mean error within +/-5mmHg and SD less than 8mmHg) and BHS protocol. / First, a mathematical model has been developed to investigate the effects of aortic BP on the aortic component (A2) in S2 produced by the vibration of the closed aortic valve. The nonlinear elasticity of aortic wall has been introduced to the model, reflecting the nature of aortic wall tissue and extending the model to the applications involving wide BP variations. The results of simulation show that the fundamental frequency and amplitude of A2 increases as aortic systolic blood pressure (SBP) is elevated, which is able to explain the 'accentuated S2' usually heard in the hypertensives. Nevertheless, the possibility of BP measurement using spectral information of externally recorded heart sounds still needs a careful examination because the frequency characteristics tends to be blurred during sound transmission. / Hypertension, known as 'a silent killer', is an important public health challenge, afflicting approximately 1 billion adults around the world. The monitoring of blood pressure (BP) is vitally important in order to identify hypertension and treat it earlier before serious health problems are developed. The conventional BP measurement provides only intermittent BP and causes circulatory interference if the cuff is inflated frequently. There is an urgent need to develop new devices which are fully wearable and unobtrusive for noninvasive and continuous monitoring of arterial BP in daily life. / Second, a modified model of heart-arterial system has been proposed in this thesis for describing the timing of aortic valve closure as a result of heart-arterial interaction. A timing parameter, RS2, was defined as the time delay from the peak of ECG R wave to the onset of S2. The study has investigated the relation between RS2 and aortic BP under varying peripheral resistance, arterial compliance, heart rate, cardiac contractility and preload. Based on the simulation results of parametric analysis, it is hypothesized that RS2 bears a significant negative correlation with both SBP and diastolic blood pressure (DBP) as the peripheral resistance, heart rate or cardiac contractility varies. / Third, in order to verify the findings of the model-based study, three experiments were carried out to explore the relationship between RS2 and BP. The alterations of RS2 in the dynamic-exercise experiments are mainly attributable to the interactive effect of the changes in heart rate, cardiac contractility and peripheral resistance, and the effect of heart rate is dominant. In two dynamic-exercise experiments, the timing parameter, RS2, exhibited a close inverse correlation with SBP (r =0.892 and r =0.845, p<0.05 in both experiments) and a moderate inverse correlation with diastolic blood pressure (DBP) (r = 0.687, p<0.05 and r =0.660, p>0.05). The correlations are comparable to those of PTT-based parameters. However, due to the restricted range of the BP variation, there was no significant correlation observed in long-term rest monitoring experiment. Moreover, the standard deviation (SD) of the errors for SBP and DBP estimated by linear fitting of 1/RS2 is close to that of PTT-based estimation. The results also suggest that the ability of RS2 on BP estimation is as good as that of the PTT based parameters. / To summarize, the original contributions of the thesis are: 1. By the introduction of the nonlinear elasticity of aortic wall, a mathematical model for the vibration of the closed aortic valve was improved and extended to the applications involving wide variations of BP To my knowledge, this represents the first study to look into the effects of aortic BP on the frequency characteristic of S2 from the theoretical point of view. / Zhang Xin-Yu. / "September 2006." / Adviser: Yuan-Ting Zhang. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 6125. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.
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Dynamic, In-Situ Pressure Measurements during CMPOsorno, Andres 26 September 2005 (has links)
A rotational setup for measuring interfacial fluid pressure and temperature was successfully constructed. Interfacial fluid measurements were performed with various slurries, slurry flow rates, and pad topographies. It was experimentally determined that the pad topography has the biggest effect in pressure and temperature distribution. This was also confirmed by tilt experiments ran in a rotational environment. For all cases, the edge high conditioned pad displayed the most changes during the experiments.
For an edge high conditioned pad, the fluid pressure was found to be mostly subambient reaching levels of up to 42 kPa at the center of the fixture, and dissipating towards the edges. The pressure maps appear to be almost center symmetric. The pressure was found to be positive during the first second of contact, and rapidly turn subambient. The Subambient pressures stabilize after about 5 seconds, and their suction force was found to slow the rotating platen significantly. Suction forces were confirmed by displacement observed during the tilt experiments. The fixtures center was sucked down into the pad up to 20 m, and tends to tilt towards the leading edge.
Interfacial temperatures were also found to vary with pad geometry. The edge-high conditioned pad exhibited changes of up to 4 C, concentrated at the center. The relative position and shape of these temperature rises matches the results observed in the pressure experiments. Temperature takes a longer time to reach equilibrium, up to 30 seconds in most measurements.
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Twenty-four hour ambulatory blood pressure and heart rate monitoring in Viet Nam veteransMuraoka, Miles Yukito January 1995 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 80-94). / Microfiche. / vii, 94 leaves, bound 29 cm
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Epidemiological and diagnostical aspects of prostatitisMehik, A. (Aare) 20 September 2001 (has links)
Abstract
The principal aim of a population-based cross-sectional survey was to generate information on the lifetime occurrence of prostatitis in Finnish men and their exposure to the disease, and also on the influence of prostatitis-related fears and disturbances on their sexual life. A second aim was to develop and clinically validate a new diagnostic tool for differential diagnosis between the forms of chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS), especially between patients belonging to categories IIIA and IIIB in the new NIH (National Institutes of Health) clinical classification.
Altogether 1832 men out of 2500 aged 20–59 years chosen randomly from the two most northerly provinces of Finland (Oulu and Lapland) participated in the epidemiological study, a response rate of 75%. The overall lifetime prevalence of prostatitis was 14.2%. The risk of having had the disease increased with age, being 1.7 times greater in the men aged 40–49 years than in those aged 20–39 years, and 3.1 times greater in those aged 50–59 years. More than a quarter of the 261 men who had or had had prostatitis symptoms (27%) suffered from them at least once a year, while 16% suffered from chronic prostatitis symptoms throughout the year. 63% of the men with prostatitis had their worst symptoms during the wintertime (November–march).
17% of the men with chronic prostatitis reported a constant fear of undetected prostate cancer. Erectile dysfunction was reported by 43% of the symptomatic men and decreased libido by 24%. Self-assessment of personality showed that the men with prostatitis were more often busy and nervous and had a meticulous attitude to life and problems than were the non-symptomatic men.
197 patients with chronic prostatitis/chronic pelvic pain syndrome participated in three clinical case-control studies during the years 1995–2000, at Oulu University Hospital, the District Hospital of Oulainen and Seinäjoki Central Hospital. The first prostatic tissue pressure measurement (PTPM) study included 34 patients and 9 controls. A novel method was developed to measure intraprostatic tissue pressure with a Stryker® intracompartmental pressure monitor. The PTPM showed a clear increase (p < 0.001) in the patients with symptoms of prostatitis and benign prostatic enlargement (BPE) relative to the controls and the patients with BPE but without pain symptoms. The second PTPM study included 42 patients with chronic prostatitis symptoms without significant BPE and 12 new controls. Significantly higher pressure readings (p < 0.001) were recorded at all three measurement points in the patients than in the controls.
48 new patients and 12 new controls were enrolled for the third PTPM study, the purpose of which was to confirm the results of the previous ones and to compare the prostatic tissue pressures of two clinical groups (IIIA and IIIB). The prostatic tissue pressure was again significantly higher in the patients with chronic prostatitis symptoms than in the controls (p < 0.001). An interesting finding was that prostatitis patients belonging to clinical category IIIA had significantly higher tissue pressures (p < 0.01) than those in category IIIB, probably reflecting more severe inflammation in the prostatic tissue.
This new PTPM method provides a more precise and/or exact tool for differential diagnosis between the forms of pelvic pain and CP/CPPS.
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Non-invasive Estimation of Blood Pressure using Harmonic Components of Oscillometric PulsesAbolarin, David January 2016 (has links)
This research presents a pulse-by-pulse analysis of Oscillometric blood pressure waveform at systolic, diastolic and mean arterial pressure points.
Using a mathematical optimization technique, pulses are characterized into component harmonic by minimizing the least square error. The results at the important pressure points are analyzed and compared for different subject using different waveform extraction techniques.
Blood pressure is estimated using the harmonic parameters. The approach studies changes in the parameters as oscillometric blood pressure recording is done. 8 harmonic parameters are obtained from the pulse characterization and are used to estimate Systolic arterial Blood Pressure, Mean arterial Blood Pressure, and Diastolic arterial Blood Pressure. The estimates are compared with our reference value to determine which has the best agreement. The proposed method is further compared with Maximum Amplitude Algorithm and Pulse Morphology Algorithm.
The effect of oscillometric waveform extraction methods on the proposed method is observed. The experiment established the fact that the extraction technique can alter the shape of oscillometric pulses. The methods were compared and it was observed that the used extraction methods did not make any significant difference on the accuracy, using this technique.
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Modélisation 3D du rachis scoliotique : fusion de données et personnalisation expérimentale / 3D modeling of the scoliotic spine : data fusion and experimental customizationGesbert, Jean-Charles 10 July 2014 (has links)
Ces travaux s'inscrivent dans le cadre d'un projet de recherche translationnel visant à améliorer la conception des corsets orthopédiques de traitement de la scoliose par la mise en place, par méthode inverse, d'un modèle biomécanique global, simplifié et personnalisé, propre au tronc de chaque patient scoliotique. Ils constituent la première étape de ce projet, à savoir, développer et mettre en œuvre des techniques, outils et protocoles permettant, d'une part, la construction d'un modèle géométrique 3D de la surface externe et des éléments internes du tronc du patient à partir de radiographies bi-planes issues d'un équipement standard et du système Model Maker (Proteor), et d'autre part, la mesure des pressions exercées par le corset ainsi que leur recalage sur les géométries reconstruites. Des reconstructions géométriques 3D du tronc avec et sans corset ainsi que des mesures de pressions ont été réalisées pour 11 patients. La conception d'un unique dispositif de calibration associé à un protocole spécifique permet l'acquisition des différentes données quasi sans déplacements du patient. Sa facilité de transport, d'installation et son faible coût, associés à un temps d'acquisition ne pénalisant pas le confort du patient, rendent envisageable son utilisation en routine clinique. L'utilisation de modèles géométriques paramétriques, associée à des équations de prédiction des paramètres anatomiques, permet d'obtenir une initialisation rapide des géométries des éléments internes du tronc à partir d'un nombre réduit de points anatomiques à numériser. Les mesures de la pression exercée par le corset, effectuées à l'aide d'un dispositif innovant muni de capteurs entièrement réalisés en fibres textiles lui permettant d'épouser parfaitement les courbes anatomiques, ont mis en avant les variations de correction, non négligeables, qu'entraînent la modification de la position du patient. / This thesis is a part of a translational research project to improve scoliosis orthopedic brace design through the use, by inverse method, of a simplified and personalized comprehensive biomechanical model for each scoliotic patient’s trunk. It represents the first step of this project, namely, to develop and to implement methods, tools and protocols allowing, on one hand, 3D reconstruction of the external shape and internal components of patient’s trunk from biplanar X-rays (performed with a standard device) and the Model Maker system (Proteor), and on the other hand, measurements of the pressure infered by the brace and their registration on the reconstructed geometry. 3D modeling of the trunk with and without brace as well as pressure measurement were carried out on 11 patients. The development of a common calibration device associated to a specific protocol allows data acquisition nearly without displacements of the patient. Its ease of transportation, installation and a low cost associated with an acquisition time which not penalize the patient’s comfort make possible its use in clinical routine. The use of parametrics geometrical models associated with prediction equations of anatomical parameters provides fast initialization of the geometries of trunk’s internal elements from a reduced number of anatomical landmarks to digitize. Measurements of the pressure infered by the brace, performed thanks to an innovative device made of pressure-sensitive textile fibers allowing it to perfectly fit anatomical curves, have highlighted significant correction variations according to the patient’s position.
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Etude numérique et expérimentale de l’interaction entre deux écoulements compressibles dans un éjecteur supersonique / Numerical and experimental study of the interaction of two compressible flows in supersonic air ejectorBouhanguel, Ala 10 December 2013 (has links)
Le travail mené dans le cadre de cette thèse porte sur l’étude expérimentale et numérique de l’écoulement au sein d’un éjecteur supersonique. Le régime d’écoulement qui s’installe dans ces appareils est très complexe du fait des phénomènes physiques qui les caractérisent comme la turbulence et les ondes de choc. Les méthodes expérimentales utilisées sont la mesure de la pression le long de l’axe de l’éjecteur `a l’aide d’une sonde développée à cet effet, la visualisation de l’écoulement par tomographie laser et la mesure de vitesse par PIV. Les simulations numériques sont réalisées à l’aide du code Ansys-Fluent en 2D axisymétrique et en 3D. Dans un premier temps, une étude de sensibilité du modèle numérique portant sur les paramètres de simulations et les modèles de turbulence est menée sur l’éjecteur fonctionnant sans flux induit. La validation des simulations repose sur une comparaison des résultats numériques avec des mesures de vitesse par PIV. Un modèle 3D s’est avéré incontournable pour l’étude de l’écoulement dans l’éjecteur avec flux induit à cause de sa géométrie complexe. Les outils expérimentaux et numériques développés permettent d’analyser finement l’interaction des flux moteur et induit, en particulier les processus de recompression par chocs obliques et de mélange. Une tentative de modélisation par LES des instabilités de l’écoulement détectées expérimentalement est également abordée. / The work reported in this thesis relates to the experimental and numerical studies of the flow within a supersonic ejector. The flow pattern which occurs in these apparatuses is very complex because of the flow phenomena encountered like flow turbulence and shock waves. The experimental methods used are the measurement of the pressure along the axis of the ejector using a specific probe developed for this purpose, the flow visualization by laser tomography and the velocity measurement by PIV. The numerical simulations are carried out using the Ansys-Fluent code with 2D axisymmetric and 3D models. First, a study of sensitivity to the numerical parameters of simulation and to the turbulence models is carried out on the ejector operating without induced flow. The validation of the simulations is achieved by a comparison between the numerical results and velocity measurements by PIV. A 3D model is necessary for the simulation of the flow in the ejector operating with induced flow because of the complex ejector geometry. The experimental techniques and the numericalmodels developed make it possible to analyze the interaction of the primary and secondary flows, in particular the process of recompression by oblique shocks and the mixing process. An attempt at modeling by LES simulation the flow instabilities detected during experiments is also approached.
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DEVELOPMENT OF A LASER LIFETIME PRESSURE-SENSITIVE PAINT METHOD FOR TURBINE ANALYSISPapa Aye Nyansafo Aye-Addo (11811563) 19 December 2021 (has links)
<p>To increase overall
aircraft engine efficiency, the diameter of the high-pressure turbine is
reduced, leading to low aspect ratio airfoils. Secondary flow dominates in
these low aspect ratio turbines, and the small airfoil geometry inhibits
flush-mounted, full-spatial dynamic pressure measurements with pressure
transducers. Airfoil surface pressure measurements are vital to understanding
the inherently unsteady flow phenomena in turbines. Additionally, aerodynamic performance
data derived from high-resolution surface pressure measurements provide
invaluable data for validating computational fluid dynamics codes used for
prediction. Non-intrusive measurement techniques such as fast-responding
Pressure Sensitive Paint (PSP) offer a potential solution of a full-field optical
measurement of surface pressure fluctuation, with each camera pixel
representing a sensor. The porous binder
improves the dynamic response of PSP,
making it suitable for unsteady flow environments such as turbomachinery
applications. In this view, the overall objective of the current doctoral
research is to develop a lifetime PSP method using laser-based excitation for
surface pressure measurement on a new class of high-pressure turbines. </p>
<p>The overall research
goal was subdivided into three main strategies. (1) A pulse lifetime calibration
procedure of a porous polymer/ceramic binder PSP was developed in a
pressure-controlled chamber to assess the correlation between pressure and time-resolved
luminescent lifetime, pressure sensitivity, and signal-to-noise ratio. (2) The
lifetime technique was implemented for surface pressure measurements in a
linear test section to measure high spatial pressure gradients and resolve
unsteady flow features. A data reduction routine and an optimal binning bundle
of pixels were proposed for calibration analysis to reduce the overall pressure
uncertainty. Uncertainty quantification and sensitivity analysis were also
completed to determine the parameters with a substantial effect on the pressure
uncertainty. (3) The pulse lifetime method was demonstrated on a high-pressure
turbine vane suction surface at engine representative conditions. The surface pressure
data were corroborated with static pressure tappings and computational
simulations. This research effort provided new insights into time-resolved
luminescent lifetime PSP techniques. Steady and unsteady flow features from
surface pressure measurements were identified using a precise calibration
method. The lifetime pulse method was effective in a high-pressure turbine flow
field, paving the way for back-to-back PSP experiments with different turbine
geometries. </p>
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