Universiẗat, Diss., 2006--Würzburg.

Der Untersuchung des Strömungsverhaltens in einer Spiralstrahlmühle kommt auf Grund ihrer Komplexität besondere Bedeutung zu. Seit der Entwicklung der Strahlmühlen wird versucht, die Abläufe während des Zerkleinerungsprozesses genau zu beobachten und zu analysieren. Als Kontrollinstrument der Betriebszustände in der Mühle hat sich die Aufzeichnung des statischen Drucks etabliert. Der statische Druck ist auf gleichem Radius unabhängig von der Position des Druckaufnehmers und damit auch unabhängig vom Einfluss der Treibstrahlen über der Wandschicht fast konstant. Weitere Untersuchungen über dem Radius der Mahlkammer bringen den Beweis, dass die aufgenommene radiale Druckkennlinie vom äußeren Mahlkammerrand in Richtung des Kammermittelpunktes abfällt. Die Aufnahme des zur Geschwindigkeitsberechnung benötigten Gesamtdrucks erfolgt über ein Pitot-Rohr. Dazu muss zunächst ein für die Mühle geeignetes Pitot-Rohr angefertigt werden. Das Pitot-Rohr mit einer Kopflänge von 13 mm und einem Verhältnis von Innendurchmesser zu Außendurchmesser von 0,73 liefert in Vergleichsmessungen die höchsten Gesamtdruckwerte und wird daher für die weiteren Versuche eingesetzt. Um den Innenraum der Mühle so vollständig wie möglich zu erfassen, werden wesentliche Einflussgrößen, wie Messposition und Eintauchtiefe des Pitot-Rohres sowie definierte radiale Positionen in der Mahlkammer schrittweise variiert. Dabei erfolgt jeweils die Ermittlung des optimalen Anströmwinkels des Pitot-Rohres. Versuche mit unterschiedlichen Eintauchtiefen des Pitot-Rohres in die Mahlkammer zeigen ebenfalls einen Druckanstieg, sobald das Messrohr in Nähe der Treibstrahldüsen ausgerichtet wird. Je weiter sich das Rohr von der Treibstrahldüse entfernt, desto niedriger sind aufgenommener Gesamtdruck und die daraus resultierende Geschwindigkeit. Die berechneten Geschwindigkeitswerte lassen sich mit Hilfe des Programms MATLAB® graphisch in Strömungsprofilen darstellen. So können besonders übersichtlich Richtung und Geschwindigkeit der lokalen Strömung in Abhängigkeit vom Radius der Mahlkammer und Position des Pitot-Rohres veranschaulicht werden. Von großer Bedeutung sind die Treibstrahlebenen sowie angrenzende Bereiche ober- bzw. unterhalb der Treibstrahlebenen, da hier ein symmetrisches Strömungsverhalten beobachtet werden kann. Diese Symmetrie wird jedoch in den nachfolgenden Ebenen, bedingt durch das Tauchrohr, durchbrochen. Der charakteristische Verlauf einer Spiralströmung kann mit Hilfe der durchgeführten Druckmessungen bestätigt werden. Das geläufige “Drei-Ebenen-Modell“ von Kürten und Rumpf zur Darstellung der Strömungsverläufe in der Strahlmühle kann an Hand der gewonnenen Erkenntnisse nicht bestätigt werden. Die vermuteten Rückströmungen lassen sich trotz Ausrichtung des Pitot-Rohres in verschiedenen Eintauchtiefen sowie an veränderten Positionen der Mahlkammer nicht beobachten. Für die Versuche mit Pulverbeladung der Mühle ist es notwendig, zunächst einen konstanten Feststoffdurchsatz zu bestimmen, bei dem stabile Betriebsbedingungen der Strahlmühle gewährleistet sind. Dazu werden Mahlvorgänge mit veränderter Förderrate des Gutes durchgeführt. Es zeigt sich, dass bei einer Förderrate von 3,49 g/min die statischen Druck- und damit Strömungsverhältnisse über eine Messdauer von 10 Minuten stabil sind. Mit dieser Einstellung werden anschließend statische Druckverläufe in Abhängigkeit von der Position des Druckaufnehmers aufgezeichnet. Ein Einfluss der Treibstrahlen auf die statischen Druckwerte ist auch hier nicht erkennbar, wie bereits in den Untersuchungen ohne Feststoffbeladung bewiesen. Die Bestimmung der Partikelgrößenverteilung und Auswertung mittels RRSB-Netz dient dabei zur Überprüfung eines erfolgreichen Zerkleinerungsprozesses. Je höher der angelegte Mahldruck, desto feinkörniger und enger verteilt ist das erhaltene Mahlprodukt. Die Aufzeichnung des Gesamtdrucks bei Feststoffbeladung verläuft hingegen nicht erfolgreich. Durch die Ausrichtung in Strömungsrichtung setzt sich das Pitot-Rohr schnell mit Pulverpartikeln zu, die sich trotz regelmäßiger Freiblasstöße nicht entfernen lassen. Es treten starke Druckschwankungen und zahlreiche Strömungsinstabilitäten auf, die eine reproduzierbare Gesamtdruckerfassung selbst über eine kurze Messdauer und damit eine genaue Berechnung der Geschwindigkeit nicht erlauben. Zusammenfassend lässt sich festhalten, dass die Messungen mittels Pitot-Rohr eine geeignete Methode zur Ermittlung des Gesamtdrucks in reinen Gasströmungen darstellen. Aus diesen Messergebnissen kann der Strömungsverlauf in der Luftstrahlmühle wiedergegeben werden, der dem einer Spiralströmung exakt entspricht. / Investigations of the flow in a spiral jet mill demand particular importance due to its complexity. Since the development of these mills began, numerous studies have aimed at improving understanding of flow processes during particle comminution. Monitoring the static pressure represents a well suitable method of controlling operating conditions in the mill. easily be calculated using the “compressible Bernoulli Equation”. Several experiments indicate that the static pressure remains nearly constant over the same jet mill radius and is dependent neither on the position of the pressure transducer nor on the influence of the jets. Further investigations of the static pressure against the radius prove the pressure decreases from circumferential radii towards the middle of the milling chamber, as expected for spiral jet streams. Recording total pressure values for subsequent calculating flow velocities requires a pitot tube. Accordingly, an appropriate pitot tube for the jet mill has to be constructed. The pitot tube with a tip length of 13 mm and a ratio of inner to outer diameter of 0,73 provides the highest total pressure data in comparative tests. Hence it will be used in the following research. Evaluating the total pressure in inner planes of the jet mill as completely as possible, essential parameters such as position and immersion depth of the pitot tube as well as defined radii of the milling chamber are varied step by step. At each measuring point the optimal direction angle of the probe has to be explored carefully. Experiments run with different immersion depths of the pitot tube in the milling chamber also show pressure data increasing when the probe is aligned near the jet nozzles. The further the probe is removed from the jet nozzle the lower are the monitored total pressure and the resultant velocity. With the help of the program MATLAB® the calculated velocity data are visualised graphically as stream profiles. Thus direction and velocity of the local flow can be illustrated particularly clearly subject to the radius of the milling chamber as well as to the position of the pitot tube. Appearing of symmetric flow properties the nozzle plane itself as well as following planes above and below this plane, respectively, demand great importance. Because of the classification tube this symmetric flow behaviour cannot further be detected in adjacent planes. These pressure measurements apparently confirm the typical profile of a spiral jet stream. Based on the measured data, the common “Drei-Ebenen-Modell” by Kürten and Rumpf describing flow processes in a jet mill cannot be confirmed. The backstreaming in the jet nozzle plane proposed in this model is not observable not even by placing the probe at different immersion depths and modified positions in the milling chamber. It is then necessary to establish a constant feed rate guarantying stable flow conditions while loading the jet mill with solid material. To this end several comminution processes are carried out with varying powder supply at different settings. Over a period of 10 minutes a feeding rate of 3,49 g/min leads distinctly to stable pressure and resultant stream conditions. With this setting all further static pressure profiles are recorded while the position of the pressure transducer is varied. An influence of the jet nozzles on the static pressure values does not become apparent as already demonstrated in preceding tests without feed. When the milling gas pressure is raised, the static pressure at circumferential radii also increases linearly. Hereby the determination of particle size distributions and analysis by the use of a RRBS-Netz serves as a check for successful grinding processes. Comparing as well location and dispersion parameters as medians of the ground material indicates that the higher the adjusted milling gas pressure is, the finer and tighter-distributed is the received comminution product. In contrast to these static pressure measurements, it is not possible to monitor total pressure profiles without difficulties. Aligning the pitot tube directly into the gas-solid stream causes fast blocking of the probe´s tip with fine particles. In spite of pulsating air blasts the pitot tube cannot be freed from this clogging. Neither an increase of the milling gas pressure nor the purgation gas pulsing for shortened-time intervals have cleaning effects on the probe. The appearance of enormous pressure fluctuations and high flow instabilities do not enable reproducible measurements of the total pressure even over a short length of time nor of correct calculations of local velocities. All in all the pitot tube represents an appropriate method of evaluating total pressure values without particle load. The measured data render stream profiles for every plane of the jet mill, each corresponding exactly to a spiral stream profile.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains v, 44 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 39-40).

Made available in DSpace on 2016-08-29T15:33:03Z (GMT). No. of bitstreams: 1 tese_6920_ERIC SIMÃO MARTINS LIMA.pdf: 1134155 bytes, checksum: 13c24c3e34bc4d1bcf89e0bb7b001051 (MD5) Previous issue date: 2013-10-16 / A indústria de petróleo e gás requer medições de vazão com baixa incerteza, uma vez que são estabelecidas por lei. Contudo, curvas e outros obstáculos são comumente encontrados nesse cenário, o que pode afetar a qualidade da medição de vazão em função de perturbações no escoamento, tais como swirl e assimetrias no perfil de velocidades. Em sistemas de gás de tocha, que são comumente utilizados como sistemas de segurança e alivio em ativos produtores de hidrocarbonetos, a sua quantificação tem sido considerada por especialistas como uma condição de medição das mais desafiadoras, tendo em vista que esses escoamentos apresentam tipicamente características tais como, instalações em grandesdiâmetros, necessidade de baixos índices de manutenção, necessidade de baixa intrusividade ao processo, variações na composição química do gás, presença eventual de líquidos (condensado ou gotículas de óleo), que contribuem para que a adequação dessa medição aos requisitos da legislação seja um problema tecnológico de elevada relevância. Medidores de vazão por ultrassom de um canal acústico são frequentemente utilizados em instalações de queima de gás de tocha, apesar de serem sensíveis a tais perturbações promovidas pela presença de acidentes de instalação. À vista disso, este trabalho visa à análise experimental do efeito de curvas na medição de Gás de tocha. Sob esse aspecto, o objetivo deste trabalho é analisar experimentalmente o comportamento das leituras de um medidor ultrassônico (UFM) sob efeito de curvas em um túnel de vento atmosférico com medição de referência por tubo de Pitot. Os resultados obtidos demonstram que as leituras do UFM sofrem influência dos efeitos de curvas quando o trecho de medição é variado. Palavras chave: Medidor ultrassônico de vazão, Pitot, gás de queima

Master of Science

Avec plus de 2 milliards de passagers transportés chaque année, l’avion reste le moyen de transport le plus sûr pour voyager. D’après différents rapports, il apparaît que 75 % des accidents sont liés à des facteurs humains présents chez les pilotes, les contrôleurs aériens, les responsables de maintenance, voire même les ingénieurs des bureaux d'études. Parmi les accidents aériens de ces dernières années, il en est un qui a été principalement meurtrier. Il s’agit du vol AF 447 du 1er Juin 2009. Après différentes enquêtes, les experts sont parvenus à la conclusion que cet accident était dû à une défaillance matérielle, en l’occurrence aux capteurs de mesure de la vitesse, les sondes de Pitot. Les différents rapports concordent sur l’hypothèque que cet accident est principalement lié à une incohérence des mesures de la vitesse renvoyées par les sondes. Cette incohérence est liée au gel des tubes de Pitot puis à une combinaison de facteurs humains résultant d’une incompréhension de la situation. Une solution technique envisageable serait d’ajouter un tube de Pitot supplémentaire, rétractable, qui permettrait de vérifier la concordance des valeurs renvoyées par les sondes fixes. La mise en place de cette nouvelle solution technique nécessite, dans un premier temps, la connaissance des différentes variables et relations qui peuvent influer sur la qualité des mesures. A partir de ces variables et relations, il devient possible de modéliser la dégradation de la qualité des mesures. Par la suite et grâce à ces modèles, des politiques d'inspection, périodique et séquentielle, peuvent être déterminées en considérant la qualité des mesures comme critère décisionnel. L'optimisation de ces politiques d'inspection sera réalisée à l'aide de procédures numériques ou de méta-heuristiques. Le travail de recherche a donc pour objectif de proposer une contribution originale à la sûreté de fonctionnement des tubes de Pitot par l'ajout d'un tube rétractable / Safety is the primary consideration in the air transportation sector. According to various accident reports, it seems that 75% of these accidents are related to human factors such as pilots, air traffic controllers, maintenance managers and even design engineers. This study is derived from an aeronautic problem defined following the crash of the Airbus 330 in the Rio-Paris flight, in 1 June 2009. Investigations concluded that the accident was due to the aircraft’s pitot tubes failure, after which the crew reacted incorrectly. In order to overcome the problem of Pitot sensors measurements inaccuracy and incoherence, we propose a technical solution which consists in setting up a fourth retractable probe to assess the Pitot sensors measurement accuracy during the flight. The implementation of this new technical solution implies a need to know the different variables that can affect the Pitot sensors measurements quality. From these variables, it is possible to model the Pitot sensors measurements quality degradation. Subsequently and thanks to these models, periodic and sequential inspection policies are proposed by considering the measurement quality degradation as a decision criterion. Optimization of these inspection policies will be carried out using numerical procedures or meta-heuristics. The current research work aims to propose an original contribution for operational safety of Pitot sensors

Performance testing methods of boilers in transient operating conditions (start, stop and combustion power modulation sequences) need the combustion rate quantified to allow for the emissions to be quantified. One way of quantifying the combustion rate of a boiler during transient operating conditions is by measuring the flue gas flow rate. The flow conditions in chimneys of single family house boilers pose a challenge however, mainly because of the low flow velocity. The main objectives of the work were to characterize the flow conditions in residential chimneys, to evaluate the use of the Pitot-static method and the averaging Pitot method, and to develop and test a calibration method for averaging Pitot probes for low 𝑅𝑅𝑅𝑅.A literature survey and a theoretical study were performed to characterize the flow conditions in in single family house boiler chimneys. The flow velocities under normal boiler operating conditions are often below the requirements for the assumptions of non-viscous fluid justifying the use of the quadratic Bernoulli equation. A non-linear calibration coefficient is required to correct for these viscous effects in order to avoid significant measurement errors. The flow type in the studied conditions changes from laminar, across the transition regime, to fully turbulent flow, resulting in significant changes of the velocity profile during transient boiler operation. Due to geometrical settings occurring in practice measurements are often done in the hydrodynamic entrance region, where the velocity profiles are neither fully developed nor symmetrical. The predicted changes in velocity profiles are also confirmed experimentally in two chimneys.Several requirements set in ISO 10780 and ISO 3966 for Pitot-static probes are either met questionably or not met at all, meaning that the methods cannot be used as such. The main issues are the low flow velocity, viscous effects, and velocity profiles that change significantly during normal boiler operation. The Pitot-static probe can be calibrated for low 𝑅𝑅𝑅𝑅, but is not reliable because of the changing velocity profiles.The pressure averaging probe is a simple remedy to overcome the problems with asymmetric and changing velocity profiles, but still keeping low the irrecoverable pressure drop caused by the probe. However, commercial averaging probes are not calibrated for the characterized chimney conditions and the information available on the performance of averaging probes at low 𝑅𝑅𝑅𝑅 is scarce. A literature survey and a theoretical study were done to develop a method for calibrating pressure averaging probes for low 𝑅𝑅𝑒 flue gas flows in residential chimneys.The experimental part consists of constructing a calibration rig, testing the performance of differential pressure transducers, and testing a prototype pressure averaging probe. The results show good correlation over a wide operation range, but the low 𝑅𝑅𝑅𝑅 characteristics of the probe could not be identified due to instability in the chosen pressure transducer, and temperature correlation for one of the probes while not for the other. The differential pressures produced are close to the performance limitations of readily available transducers and it should be possible to improve the method by focusing on finding or building a suitable pressure transducer. The performance of the averaging method can be improved further by optimizing the geometry of the probe. Another way of reducing the uncertainty would be to increase the probe size relative to the conduit diameter to produce a higher differential pressure, at the expense of increasing the irrecoverable pressure drop.

Ce travail de maîtrise a pour objectif le développement, la construction et la validation d'une sonde de pression cinq trous instationnaire avec capteurs embarqués. Celle-ci s'intègre dans le programme de recherche du laboratoire de machines hydraulique de l'université Laval et vient compléter les systèmes de mesures P.I.V. et L.D.V. que le laboratoire possède déjà. La première phase de ce travail a été l'établissement d'un cahier des charges ainsi qu'une revue bibliographique sur les sondes du même type déjà existantes. Puis les deux phases principales de ce travail ont été les phases de conception et de construction de la sonde. Plusieurs modifications de plans ont été nécessaires afin d'arriver à une sonde la plus petite possible tout en respectant les nombreuses contraintes du cahier des charges de l'étalonnage et de la construction. La majeure partie de la construction a été effectuée à l'atelier du département de génie mécanique de l'université, mais le montage des capteurs ainsi que l'usinage de la tête de la sonde ont dû être sous-traités à des entreprises extérieures. L'étalonnage de la sonde a été réalisé en deux parties. La première partie est l'étalonnage des capteurs. Il a été réalisé au moyen d'un réservoir d'air comprimé, ce qui nous a aussi permis de vérifier l'étanchéité de la sonde. La seconde partie est l'étalonnage de la sonde elle-même, qui, pour des raisons de disponibilité n'a pu être réalisé dans un canal hydraulique mais dans un jet d'air calibré. L'utilisation de l'air a posé deux principaux problèmes : l'impossibilité d'atteindre les mêmes vitesses que dans l'eau (en similitude de Reynolds) et les pressions dynamiques mesurées sont beaucoup plus faibles dans l'air que dans l'eau. Pour les faibles vitesses on arrive à la limite de sensibilité des capteurs. Une autre série de mesures a permis de mettre en évidence les limites d'utilisation de la sonde selon cet étalonnage, soit 31 m /s dans l'air, équivalent à 2 m /s dans l'eau et une plage de direction pour l'angle d'écoulement entre ± 25° pouvant aller jusqu'à ± 45° suivant les conditions. Afin de valider totalement la sonde il faut encore réaliser des essais de réponse en fréquences et réaliser un système permettant d'étalonner la sonde dans un canal hydraulique afin de vérifier son comportement (vibrations) ainsi que la réponse des capteurs à 10 '7S. / This work is presented in partial fulfillment of a Master Degree. Its objectives arc the development, construction and validation of a five-hole probe with embedded sensors to measure non stationary pressures. This new measuring instrument will be used for the research programme of the Laboratory of hydraulic machines of Laval University. It is additional to the P.I.V. and L.D.V measurement Systems already existing at the laboratory. The first phase of this work consisted of the establishment of specifications as well as a bibliographical review of existing probes of the same type. Then two important phases of this work were the design and construction of the probe. Several design modifications were necessary in order to produce the smallest possible probe while respecting the many constraints of the specifications calibration and construction. The major portion of the actual construction was carried out at the workshop of the Mechanical Engineering Department of the University, but the assembly of the sensors as well as the machining of the probe head were sub-contracted to external firms. The calibration of the probe was carried out in two parts. The first part was the calibration of the sensors. This was done by means of a compressed air tank which allowed us to verify also if the probe is waterproof. The second part was the calibration of the probe it self, which, for reasons of availability, could not be produced in a hydraulic channel but in a gauged air jet. The use of air brought two principal problems: the impossibility of reaching the high speeds encountered in water (following similarity of Reynolds number) and a much weaker measured dynamic pressures in air than in water. For low speeds, one reaches the limit of sensitivity of the sensors. Another series of measurements made it possible to highlight the operational limits of the probe according to the calibrated zone, that is to say 31 m/s in the air corresponding to 2 m/s in water and the direction of the flow angle between ± 25°, and ± 45° for certain conditions. In order to completely validate the probe, it is still necessary to carry out tests for the frequency response and to build a hydraulic channel to check the probe's behavior regarding vibrations as well as to calibrate the response of the sensors up to 10 m/s.

O presente trabalho trata do desenvolvimento de uma sonda de pressão para medição de magnitude e direção da velocidade em um escoamento de ar. Primeiramente, é feita uma pesquisa sobre métodos e instrumentos de medição de velocidade de escoamentos de ar, utilizando a literatura existente sobre os tipos de medidores e suas restrições e capacidades na medição de direção do escoamento. Em seguida, são escolhidos dois tipos de medidores capazes de atender aos requisitos de fabricação simples e robusta, sendo um deles aplicado a escoamentos bidimensionais (sensor de três orifícios, tipo prisma) e o outro, a escoamentos tridimensionais (sensor de cinco orifícios, tipo pirâmide). É feito o projeto detalhado destes medidores e define-se o método de fabricação dos mesmos, comparando o método da prototipagem rápida com a usinagem. Uma vez fabricados os sensores, são realizados ensaios de caráter investigativo para mensurar a faixa de ângulos de medição de cada sensor. De posse dos resultados, é feito um estudo sobre os coeficientes adimensionais utilizados para a definição do ângulo de escoamento a partir das medições de pressão realizadas pelo sensor. É proposto um novo conjunto de coeficientes adimensionais com os quais se determina uma faixa de medição de ângulos entre -25 e + 25 para a sonda tipo prisma e uma faixa entre -35 e + 35 para a sonda tipo pirâmide. Finalmente, são feitas as curvas de calibração para os sensores e se discute sobre suas aplicações na medição de velocidade de escoamentos de ar. / The present work deals with the development of a pressure probe for measuring magnitude and direction of velocity from an air flow. Initially, it is made a review of methods and instruments to measure air flow velocity, using the existing literature on kinds of instruments with their restrictions and capabilities on flow direction measurement. Secondly, two kinds of sensors are chosen based on the requirements of easy and robust manufacturing, being one of them applied to bi-dimensional flows (three-hole probe, prism type) and the other one for tri-dimensional flows (five-hole probe, pyramid type). The detailed design of these probes is made and the fabrication method is chosen comparing the fast prototyping method with machining. Once these sensors are manufactured, investigative tests are carried out in order to measure the flow angle range for each sensor. With these results, a study is made on the non-dimensional coefficients used for definition of flow angle from the pressure measurements from the sensor. A new set of non-dimensional coefficients is proposed and a flow angle range between -25 and + 25 is determined for the prism probe and a range between -35 and + 35 for the pyramid probe, Finally, the calibration curves are made for the two sensors, followed by a discussion on the applications on air flow velocity measurements.

Made available in DSpace on 2014-06-11T19:23:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-12-16Bitstream added on 2014-06-13T19:06:57Z : No. of bitstreams: 1 eguti_cca_me_ilha.pdf: 4013696 bytes, checksum: 9efc5c11950fccddb62667186e778ef2 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Anemômetros de fio quente são sensíveis instrumentos capazes de medir variações de velocidade nos mais diversos tipos de escoamentos, sejam eles gasosos ou líquidos. Um delicado filamento metálico é aquecido por uma corrente elétrica a qual gera calor por efeito Joule e transfere parte dessa energia para o escoamento incidente, sendo esta troca de calor proporcional a velocidade do fluído, definindo assim o princípio básico de funcionamento da anemometria de fio quente. Quando este filamento é montado num circuito tipo ponte de Wheatstone, pode-se relacionar a troca de calor no filamento através da variação de sua resistência elétrica fazendo o uso de circuitos eletrônicos especiais. Este trabalho aborda os conceitos básicos da anemometria de fio quente, seus circuitos de controle principais e seus modos de operação, mostrando diferentes métodos para calibração de sondas de fio quente em escoamentos gasosos, além de apresentar uma metodologia completa para construção de um sistema básico de anemômetro de fio quente de temperatura constante. Dois dispositivos foram construídos e testados sendo avaliados quanto ao seu funcionamento e sua resposta em freqüência. / Hot wire anemometers are sensitive instruments capable of measuring fluctuation of speed in many fluid flows, gaseous or liquid. A delicate metallic filament is heated by an electric current (Joule effect) and cooled by incident flow, this heat exchange is proportional of the fluid speed, defining the basic phenomenon of hot-wire anemometry. When this filament is mounted on an arm of Wheatstone bridge, the heat lost by the filament can be related its electric resistance when special electronic circuits are used. This work presents the concepts of hot-wire anemometry, its main control circuits and its operation mode, showing the basic methods for hot wire calibration with gaseous flows, besides presenting a complete methodology for construction of a basic constant temperature hot-wire anemometer system, based on the tests of two experimental circuits which are evaluated by electronic tests and its frequency response.