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In this thesis an investigation for the identification, measurement and modelling of the gear pump performance under marginal suction condition, created in the suction line and resulting in cavitation at the suction port and cavitation erosion on the delivery side plate is introduced. A new technique for the detection of cavitation in gear pumps has been employed and proved to be more efficient and less expensive than other techniques available. The experimental study has been carried out by monitoring the pressure ripple at the pump inlet and outlet, as well as investigating the pressure distribution around the gear rotor under cavitating and non-cavitating conditions. It was found that the gear pump cavitation appeared in three distinct stages, these being cavitation-inception, discrete-cavitation and continuous-cavitation. These stages of cavit tion were investigated by means of pressure distribution around the gear rotor using a miniature pressure transducer positioned at a gear fillet. The experimental results demonstrate a drop in filling efficiency, of the tooth space due to cavitation, which provides a further understanding of the pump performance characteristics at different inlet conditions. An expression for the definition of transient pressure in the tooth space due to trapped volume has been derived for the first time and proved to give a good correlation with published experimental work. A surface analysis technique has been employed in this work to study the behaviour of the material erosion due to cavitation bubble collapse, using a 'Talysurf 41 instrumentation system, and the results obtained are in good agreement with those published by NEL.

Jet impingement heating and cooling techniques are used extensively in industrial applications. in some of these installations, the axis of the jet can be inclined relative to the impingement surface. The impingement flow is then unsynLmetrical so that the heat transfer rates are modified. At present, there is a lack of information concerning the effect of inclination on jet impingement heat transfer. Thus, the experimental study reported in this thesis is primarily concerned with the measurement of local and average heat transfer coefficients associated with the impingement of inclined turbulent circular jets onto flat plates. A single free jet exiting into initially stagnant surroundings was considered and the nozzle inclination was varied from 300 to 900 to the surface. The tests covered the range: Z/d (nozzle-target separation) of 6 to 16 and Re (jet Reynolds number based on exit conditions) of 32500 to 65000. The effect of the exit nozzle shape was also determined. In multiple jet systems, the flow from the upstream jets can significantly affect those situated in the downstream section. Thus, the effect of nozzle inclination on the performance of an impinging jet exiting into a cross flow was also investigated. Thus, as well as the angle of inclination (a), the magnitude of the cross flow (Uc) and the width of the duct (H/d) were also altered in this confined situation. The ranges of these variables were 300<a<l350,55Uj/Uc520.9 and UH/d426. A 'thin-film' naphthalene sublimation technique was used to measure the variation of the mass transfer rates over the impingement surface and these rates were converted to heat transfer data by invoking the Chilton-Colburn analogy between the two processes. The average heat transfer coefficients quoted in the'text were obtained by numerically integrating the local values. The thin-film naphthalene sublimation technique yielded repeatable results which were generally in good agreement with published data for the limited cases for which comparisons-were possible. ' For the unconfined jets, inclining the nozzle reduced the heat transfer rates. The stagnation point, impingement region and average heat transfer coefficients were correlated by means of simple power law relationships which involved the Reynolds number (Re), the nozzle-target separation (z/d) and the angle of inclination (a). Both circular and elliptical-shaped nozzles produced essentially similar results so that it appears that the shape of the velocity profile at the jet exit can be neglected for the conditions studied in this invest: i. gation. For the confined situations, it was found that superimposing a cross flow onto the jet reduced the heat transfer rates and this is in agreement with the results of previous investigators. At low cross flows, inclining the nozzle further reduced the heat transfer rates. However, at higher cross flows, inclining the nozzle could lead to an increase in heat transfer rates and an angle of inclination of approximately 600 was found to yield optimal results. This optimal appears to result from a balance between two conflicting effects, namely that inclination reduces heat transfer but also simultaneously increases the penetration of the jet upstream into the cross flow. Limited velocity and turbulence measurements were undertaken for the jets in order to characterise the flow. These measurements were in good agreement with data from previous investigations so that the heat transfer results from this study should be applicable in a fairly general manner. In order to explain the heat transfer results, flow visualization studies were also carried out.

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Para algumas categorias de produtos, insumos como embalagem podem ter um peso significativo na composição do custo do produto final. No caso de vários produtos embalados em frascos plásticos este é um cenário comum que tem como conseqüência uma exigência de aumento de desempenho das máquinas sopradoras que produzem tais frascos. Com o objetivo de cumprir tal exigência, este trabalho realiza uma análise do sistema hidráulico de uma sopradora para redução do tempo de posicionamento nos principais movimentos executados por alguns dispositivos vitais, os quais possuem comandos eletrohidráulicos de controle de posição e velocidade constituídos de válvulas hidráulicas de controle de vazão, válvulas direcionais proporcionais e atuadores lineares. A forma desta análise é conduzida inicialmente através da modelagem dos componentes hidráulicos envolvidos nos movimentos destes dispositivos e, posteriormente, de um ensaio através do registro das grandezas físicas de interesse como pressões e velocidades de posicionamento utilizando como bancada de testes uma sopradora existente. O desempenho atual do equipamento em questão, registrado através do ensaio, pode ser então comparado com os resultados obtidos na modelagem para uma análise final com o objetivo de tornar a sopradora mais rápida e produtiva além de validar o modelo estabelecido para a realização de projetos futuros. / Many times, for some products classes, inputs as packaging may have an expressive weight in the final product cost structure. In the case of products packaged into plastic containers, this is an usual scenario that has as result, the increase of performance requirements of the blow mold machines that produce such containers. A point to be studied in the blow mold machines to fulfill such requirement is an analysis of its hydraulic system in a way to reduce the positioning time in the most significant movements performed by its main devices. Such devices have electro-hydraulic position and speed controls composed by flow control and proportional valves and linear actuators. So, it is presented in this work the description of blow mold machine, modeling of hydraulic components involved with the main equipment\'s movements and an experience to record physical values as pressures and positioning speeds using an existent blow mold machine as testing bench. The tested registers can be confronted against the results obtained in the modeling analysis as a target to make the blow mold machine more productive besides of validate the model to the future projects.

Η διπλωματική εργασία αφορά τον έλεγχο και τη μοντελοποίηση ενός συστήματος τριών δεξαμενών για την ανάμιξη υδατικών διαλυμάτων. Το σύστημα χρησιμοποιεί δύο ανεξάρτητες δεξαμενές αποθήκευσης (tanks) υγρών διαλυμάτων διαφορετικών χρωμάτων. Στόχος της λειτουργίας του συστήματος ελέγχου είναι η επίτευξη καθορισμένης χρωματικής σύνθεσης στα πλαίσια δημιουργίας του τελικού διαλύματος εντός της τρίτης δεξαμενής, η σύνθεση του οποίου καθορίζεται μέσω ενός αισθητήρα φωτεινότητας. Ο αισθητήρας φωτεινότητας «επιστρέφει» κατάλληλα διαμορφωμένο ηλεκτρικό σήμα «ανάλογο» της διερχόμενης φωτεινότητας από το διάλυμα, η οποία εξαρτάται από τη σύνθεση του διαλύματος. Επιπρόσθετα στην επιθυμητή χρωματική σύνθεση, το σύστημα θα πρέπει να λαμβάνει υπόψη του, κατά τη λειτουργία του, προδιαγραφές ελαχίστου – μεγίστου τελικής στάθμης/όγκου για το διάλυμα της σύνθεσης. Τέλος, εκτός του «ανοικτού» συστήματος ανάμιξης, μελετάται η χρήση PID (Proportional – Integral – Derivative) Ελεγκτή με στόχο τη χρονικά δυναμική αντιστάθμιση και προσαρμογή της λειτουργίας του συστήματος σε ενδεχόμενες μεταβολές των υποσυστημάτων, των παραμέτρων ή των διεργασιών του, διασφαλίζοντας μία ευρύτητα συνθηκών ευσταθούς λειτουργίας. / Project concerns the modeling and control of of a three-tank system for mixing liquids. The system uses two independent storage tanks filled with different colors liquid. The aim of the operation of the control system is reaching a specified color in the third tank, the composition of which is determined by a brightness sensor. The brightness sensor 'returns' suitably shaped electrical signal. In addition to the desired color composition, the system should take into account, during operation, specifications minimum - maximum final level / volume for the solution of the composition. Finally, it is studied the use of PID (Proportional - Integral - Derivative) Controller.